GPS for Nikon

[Eric Stevens]

I've been looking around and am disconcerted to find that all GPS
units seem to have a spotty reputation. Problems seem to include slow
satellite and position acquistion if the camera has been moved since
last time, errors in elevation, difficulty in crossing the equator
etc. Then there is their effect on battery life if you leave them
turned on.

I know that only people with a grouch tend to write reviews but surely
they can't be as bad as I have read.

I'm primarily looking for a GPS to tag my photographs so that 2 years
down the track I know which city I took them in. I need a fast start
up when I haul the camera out so that the rest of the mob has not
disappeared before my camera is ready to take a photograph.

I will be using a Nikon D300 and will be interested in hearing of
other people's experience and comments.
--

Regards,

Eric Stevens

[Savageduck]

On 2013-04-27 17:37:51 -0700, Eric Stevens <eric.s...@sum.co.nz> said:

> I've been looking around and am disconcerted to find that all GPS
> units seem to have a spotty reputation. Problems seem to include slow
> satellite and position acquistion if the camera has been moved since
> last time, errors in elevation, difficulty in crossing the equator
> etc. Then there is their effect on battery life if you leave them
> turned on.

I use the Nikon GP-1 with my D300S. If my camera has been turned off
for any considerable time, the GP-1 takes between 45 seconds to two
minutes to obtain initial Sat acquisition. Once that is done and I am
outdoors I leave the camera on, and the additional battery drainage is
negligible. However I am using the Nikon MB-D10 grip + EN-EL4 battery.

After initial acquisition it performs well, even when briefly having
clear sky obscured by a tent, marquee, or tree cover. However heavy
tree cover can, and has interrupted the signal causing a failure to
record the data.

> I know that only people with a grouch tend to write reviews but surely
> they can't be as bad as I have read.

I have no complaints, as I am aware of and accept the limitations.

> I'm primarily looking for a GPS to tag my photographs so that 2 years
> down the track I know which city I took them in. I need a fast start
> up when I haul the camera out so that the rest of the mob has not
> disappeared before my camera is ready to take a photograph.

There are a few things I do if I am going into a building, museum,
gallery, etc., or if I have to make a grab shot before Sat acquisition
is made.
1. Take a reference shot with complete GPS data either before entering
the building or after leaving.
2. For the unexpected grab shot(s), take a GPS reference shot after
acquisition is made.

Now comes the part you will not like. I use Lightroom 4 "Mapping" mode
to add GPS data from the reference shots to the appropriate shots
lacking the data.

If I am using my G-11, which does not have GPS, I will find the
location using Lightroom 4 "Mapping" mode, and place the G-11 shots
appropriately. Now that I have my iPhone with GPS, I will take a
reference shot with that (usually of nothing of any importance) to get
a GPS reference for my G-11.

I am sure that there is other mapping/editing software which will
permit adding GPS data to the metadata, but I find LR4 to be the
simplest to work with.

Here is LR4 "mapping" showing where I dragged my ass all over Laguna
Seca. As you zoom in on the location flags it will separate and show
more accurate positioning. Zoom out and the tags get consolidated.
< https://dl.dropbox.com/u/1295663/FileChute/screenshot_205.jpg >
< https://dl.dropbox.com/u/1295663/FileChute/screenshot_206.jpg >
< https://dl.dropbox.com/u/1295663/FileChute/screenshot_207.jpg >

So if you take one of my shots from that day:
< http://db.tt/TtJ20HXK >
and paste that URL into "Jeffery's EXIF Viewer" you should get this result.
< http://regex.info/exif.cgi?imgurl=http%3A%2F%2Fdb.tt%2FTtJ20HXK >

...but as I said I get that location info with LR4 or Apple's "Preview".

> I will be using a Nikon D300 and will be interested in hearing of
> other people's experience and comments.


--
Regards,

Savageduck

[Eric Stevens]

Can Photoshop do this also?

>
>If I am using my G-11, which does not have GPS, I will find the
>location using Lightroom 4 "Mapping" mode, and place the G-11 shots
>appropriately. Now that I have my iPhone with GPS, I will take a
>reference shot with that (usually of nothing of any importance) to get
>a GPS reference for my G-11.
>
>I am sure that there is other mapping/editing software which will
>permit adding GPS data to the metadata, but I find LR4 to be the
>simplest to work with.
>
>Here is LR4 "mapping" showing where I dragged my ass all over Laguna
>Seca. As you zoom in on the location flags it will separate and show
>more accurate positioning. Zoom out and the tags get consolidated.
>< https://dl.dropbox.com/u/1295663/FileChute/screenshot_205.jpg >
>< https://dl.dropbox.com/u/1295663/FileChute/screenshot_206.jpg >
>< https://dl.dropbox.com/u/1295663/FileChute/screenshot_207.jpg >
>
>So if you take one of my shots from that day:
>< http://db.tt/TtJ20HXK >
>and paste that URL into "Jeffery's EXIF Viewer" you should get this result.
>< http://regex.info/exif.cgi?imgurl=http%3A%2F%2Fdb.tt%2FTtJ20HXK >
>
>...but as I said I get that location info with LR4 or Apple's "Preview".
>
>> I will be using a Nikon D300 and will be interested in hearing of
>> other people's experience and comments.
--

Regards,

Eric Stevens

[Savageduck]

No.

>> If I am using my G-11, which does not have GPS, I will find the
>> location using Lightroom 4 "Mapping" mode, and place the G-11 shots
>> appropriately. Now that I have my iPhone with GPS, I will take a
>> reference shot with that (usually of nothing of any importance) to get
>> a GPS reference for my G-11.
>>
>> I am sure that there is other mapping/editing software which will
>> permit adding GPS data to the metadata, but I find LR4 to be the
>> simplest to work with.
>>
>> Here is LR4 "mapping" showing where I dragged my ass all over Laguna
>> Seca. As you zoom in on the location flags it will separate and show
>> more accurate positioning. Zoom out and the tags get consolidated.
>> < https://dl.dropbox.com/u/1295663/FileChute/screenshot_205.jpg >
>> < https://dl.dropbox.com/u/1295663/FileChute/screenshot_206.jpg >
>> < https://dl.dropbox.com/u/1295663/FileChute/screenshot_207.jpg >
>>
>> So if you take one of my shots from that day:
>> < http://db.tt/TtJ20HXK >
>> and paste that URL into "Jeffery's EXIF Viewer" you should get this result.
>> < http://regex.info/exif.cgi?imgurl=http%3A%2F%2Fdb.tt%2FTtJ20HXK >
>>
>> ...but as I said I get that location info with LR4 or Apple's "Preview".
>>
>>> I will be using a Nikon D300 and will be interested in hearing of
>>> other people's experience and comments.


--
Regards,

Savageduck

[David Taylor]

Slightly round-about, I take a Garmin GPSmap 60 CSx round always (it is
clipped to my belt) and I use GeoSetter to tag the photos after the
event. It relies on the camera time being reasonably accurate, so I
usually take a photo of the GPS once per day to be able to offset the
camera time in GeoSetter. The SmartPhone and the iPad usually don't
require this as they have GPS built-in, as does my newer bridge camera.
I would rather not have a bulk add-on to the D300 (or in my case, the
compact D5200).
--
Cheers,
David
Web: http://www.satsignal.eu

[Graham]

On Sun, 28 Apr 2013 12:37:51 +1200, Eric Stevens,
<news:s7ron853kp979mpoo...@4ax.com> expounded this
theory:

I use a Solmeta N3-A. I've had it for about two years and it has
performed faultlessly.
http://www.solmeta.com/index.php/Product/show/id/2

I previously used a "Promote"
http://www.promotesystems.com/products/Promote-GPS.html and it was
almost useless, often failing to lock on for hours if at all.
Eventually it stopped working altogether.

Once the Solmeta has acquired the signal, which is fast, it is rock
solid. Turn off the camera for an hour or so and the signal is
re-acquired instantly. I'm more than happy with it.

--
Graham
Comments and criticism welcome
http://www.lodeway.com

[Me]

On 28/04/2013 1:34 p.m., Savageduck wrote:
> On 2013-04-27 17:37:51 -0700, Eric Stevens <eric.s...@sum.co.nz> said:

> I use the Nikon GP-1 with my D300S. If my camera has been turned off for
> any considerable time, the GP-1 takes between 45 seconds to two minutes
> to obtain initial Sat acquisition. Once that is done and I am outdoors I
> leave the camera on, and the additional battery drainage is negligible.
> However I am using the Nikon MB-D10 grip + EN-EL4 battery.
>
> After initial acquisition it performs well, even when briefly having
> clear sky obscured by a tent, marquee, or tree cover. However heavy tree
> cover can, and has interrupted the signal causing a failure to record
> the data.
>

This is nuts. My android phone has a GPS that takes a fraction of that
time to acquire a fix (satellite only), heavy tree cover not a problem.
It also outperforms (signal strength/processing grunt) my in-car GPS and
my lowrance marine GPS by a mile (each of which cost much more than the
phone).
Qualcomm etc make "combo" GPS/bluetooth/wifi chipsets for phones. They
must be cheap - my phone (no plan) was very inexpensive.
DSLR makers should dump proprietary firmware/OS.

[Alan Browne]

On 2013.04.28 07:14 , Me wrote:
> On 28/04/2013 1:34 p.m., Savageduck wrote:
>> On 2013-04-27 17:37:51 -0700, Eric Stevens <eric.s...@sum.co.nz> said:
>
>> I use the Nikon GP-1 with my D300S. If my camera has been turned off for
>> any considerable time, the GP-1 takes between 45 seconds to two minutes
>> to obtain initial Sat acquisition. Once that is done and I am outdoors I
>> leave the camera on, and the additional battery drainage is negligible.
>> However I am using the Nikon MB-D10 grip + EN-EL4 battery.
>>
>> After initial acquisition it performs well, even when briefly having
>> clear sky obscured by a tent, marquee, or tree cover. However heavy tree
>> cover can, and has interrupted the signal causing a failure to record
>> the data.
>>
> This is nuts. My android phone has a GPS that takes a fraction of that
> time to acquire a fix (satellite only), heavy tree cover not a problem.
> It also outperforms (signal strength/processing grunt) my in-car GPS and
> my lowrance marine GPS by a mile (each of which cost much more than the
> phone).

See below. You don't want your marine GPS to be too "performing"
(though out on the water it should not have any trouble at all).

> Qualcomm etc make "combo" GPS/bluetooth/wifi chipsets for phones. They
> must be cheap - my phone (no plan) was very inexpensive.
> DSLR makers should dump proprietary firmware/OS.

Bragging on GPS sensitivity in difficult situations like heavy tree
cover is a two edged sword.

"Aggressively" sensitive receivers have higher position error in such
conditions with occasional wildly off results.

The first victim is geometric. In heavy woods it's near impossible to
track the satellites at lower elevation (nearer the horizon). Those
satellites of course contribute most to horizontal accuracy.

The second victim is correlation tracking. Other than the satellites
near vertical, the signal is poor so the tracker correlation function is
"noisier" for the mid to low elevation satellites - that equates to a
less accurate horizontal position as well.

As always: TANSTAAFL.

--
"A Canadian is someone who knows how to have sex in a canoe."
-Pierre Berton

[Alan Browne]

On 2013.04.27 21:34 , Savageduck wrote:

> After initial acquisition it performs well, even when briefly having
> clear sky obscured by a tent, marquee, or tree cover. However heavy tree
> cover can, and has interrupted the signal causing a failure to record
> the data.

A tent shouldn't affect GPS at all unless it has a metalic component.

[nospam]

In article <klj0ak$r93$1...@news.albasani.net>, Me <anywh...@here.com>
wrote:

> > I use the Nikon GP-1 with my D300S. If my camera has been turned off for
> > any considerable time, the GP-1 takes between 45 seconds to two minutes
> > to obtain initial Sat acquisition. Once that is done and I am outdoors I
> > leave the camera on, and the additional battery drainage is negligible.
> > However I am using the Nikon MB-D10 grip + EN-EL4 battery.
> >
> > After initial acquisition it performs well, even when briefly having
> > clear sky obscured by a tent, marquee, or tree cover. However heavy tree
> > cover can, and has interrupted the signal causing a failure to record
> > the data.
>
> This is nuts. My android phone has a GPS that takes a fraction of that
> time to acquire a fix (satellite only), heavy tree cover not a problem.

smartphones use the cellular network to speed up the time to get a fix
and handle situations where gps reception is weak, such as under heavy
tree cover.

if cameras had cellular phones in them, they could do that too.

> It also outperforms (signal strength/processing grunt) my in-car GPS and
> my lowrance marine GPS by a mile (each of which cost much more than the
> phone).

doubtful.

> Qualcomm etc make "combo" GPS/bluetooth/wifi chipsets for phones. They
> must be cheap - my phone (no plan) was very inexpensive.
> DSLR makers should dump proprietary firmware/OS.

that's a separate issue.

[Alan Browne]

On 2013.04.27 20:37 , Eric Stevens wrote:
> I've been looking around and am disconcerted to find that all GPS
> units seem to have a spotty reputation. Problems seem to include slow
> satellite and position acquistion if the camera has been moved since
> last time, errors in elevation, difficulty in crossing the equator
> etc. Then there is their effect on battery life if you leave them
> turned on.
>
> I know that only people with a grouch tend to write reviews but surely
> they can't be as bad as I have read.

In my experience rosy GPS reviews are biased in some way or another.

There exists no GPS that is perfect. Physics prevails. Too sensitive
looks good to the user (but he often can't tell how bad the data is).
OTOH, a hiking GPS doesn't have to be especially accurate for safety of
life purposes.

That said, since the early handheld GPS days, battery life has improved
enormously. My first handheld that I owned was a 12-channel Lowrance
that used 8 AA batteries and that would last, maybe, 5 hours.

> I'm primarily looking for a GPS to tag my photographs so that 2 years
> down the track I know which city I took them in. I need a fast start
> up when I haul the camera out so that the rest of the mob has not
> disappeared before my camera is ready to take a photograph.
>
> I will be using a Nikon D300 and will be interested in hearing of
> other people's experience and comments.

I've been using the AMOD-3080 for several years. They are purely
loggers with 6 recording modes (1s, 5s and 10s and each of those rates
has "simple position data" or "rich data"). With 128 MB of memory, even
on the 1s/rich data mode it has capacity for 72 hours. At lower rates
over 1000. I clip it to a ring on my backpack or put it under my tuque
in the winter.

If the device was recently used (a few days), the startup time is 30
seconds or better. On a photo outing I don't shut it off. It records
the voyage as well as the photo locations.

Since starting it in the woods will both take longer (many minutes) and
will initially have a large error (100+ metres for a minute or more),
it's better that it be up and running before entering the woods. (This
is true of any GPS, BTW).

Open sky accuracy is quite good at better than 3m (when SBAS sats are
received), otherwise better than 10 metres is pretty much assured with
<5m typical.

Note, at lower latitudes you're more likely to get a usable SBAS signal
in the woods (Japan, Europe and US [MSAS, EGNOS and WAAS resp.]). But
here in Canada it's less likely.

In the woods, it's more variable and gets worse with wood density. On
some trails nearby (that I have mapped accurately over the years), it
can be within a few metres or off by 20 - 30 metres depending on the
constellation available at the time and foliage conditions. Naturally
in the deciduous portion of the forest the best results are in winter.

I use 5s/rich data. This gives me 12+ hours on alkaline batteries.

The data is in plain text NMEA-0183 format. No PC software required to
get the data off the unit. The unit looks like a USB memory stick to
the computer.

Here is a copy exactly as it came out of the unit (I moded the name).
https://www.dropbox.com/s/h5x8y87snfdqxwv/GPS_Morin-Heights-20120722_170959.log
You can open that in Google Earth.

I use command line "Exiftool" (PC, Mac, Linux ...) to tag the photos,
though many tagging tools will do the job as well (PC, Mac and probably
Linux).

There is now a rechargeable version of the 3080. But I won't get it.

The advantage to me is to use alkaline. On trips, hikes etc., I can
carry the AAA batteries in a bag bundled in 3's. Dead batts go into a
pouch in my backpack for eventual disposal at the recyc centre.

NiMH's just don't last as long as the Alk's and aren't convenient for
trips and hiking.

[Savageduck]

On 2013-04-28 06:21:24 -0700, Alan Browne

<alan....@FreelunchVideotron.ca> said:

> On 2013.04.27 21:34 , Savageduck wrote:
>
>> After initial acquisition it performs well, even when briefly having
>> clear sky obscured by a tent, marquee, or tree cover. However heavy tree
>> cover can, and has interrupted the signal causing a failure to record
>> the data.
>
> A tent shouldn't affect GPS at all unless it has a metalic component.

Agreed. As I stated above, the GP-1 performs well, even when briefly
having clear sky obscured by a tent.
The example shot I provided was shot in a tent.

--
Regards,

Savageduck

[Alan Browne]

On 2013.04.28 10:04 , nospam wrote:
> In article <klj0ak$r93$1...@news.albasani.net>, Me <anywh...@here.com>
> wrote:
>
>>> I use the Nikon GP-1 with my D300S. If my camera has been turned off for
>>> any considerable time, the GP-1 takes between 45 seconds to two minutes
>>> to obtain initial Sat acquisition. Once that is done and I am outdoors I
>>> leave the camera on, and the additional battery drainage is negligible.
>>> However I am using the Nikon MB-D10 grip + EN-EL4 battery.
>>>
>>> After initial acquisition it performs well, even when briefly having
>>> clear sky obscured by a tent, marquee, or tree cover. However heavy tree
>>> cover can, and has interrupted the signal causing a failure to record
>>> the data.
>>
>> This is nuts. My android phone has a GPS that takes a fraction of that
>> time to acquire a fix (satellite only), heavy tree cover not a problem.
>
> smartphones use the cellular network to speed up the time to get a fix
> and handle situations where gps reception is weak, such as under heavy
> tree cover.
>
> if cameras had cellular phones in them, they could do that too.
>
>> It also outperforms (signal strength/processing grunt) my in-car GPS and
>> my lowrance marine GPS by a mile (each of which cost much more than the
>> phone).
>
>doubtful.

It depends what he means by "outperform". If it means faster
acquisition, he's right - but he'll have no idea how bad the quality of
the solution is.

A marine GPS (like aviation) should be conservative. That results in
slower acquisition, but better certainty about the quality of the
solution. Since marine units operate in areas without much obstruction
to the sky (typically) a conservative acquisition/tracking threshold is
a good idea. Some marine units also allow you to enter the altitude of
the surface you are on (lake elevation for example) and that gives you a
"free" virtual satellite located at the center of the earth.

(Indeed, if the altitude setting is used, but incorrect by a good bit,
it will drag the position solution with it a good way unless RAIM is
used to discard it. I don't believe any marine units use RAIM however).

I don't have much of an opinion on automobile GPS sets. They seem to do
well, but will occasionally show a wild error (show position on a
parallel street 2 blocks away; or on the service road, etc.).

Mine seems to use the map for position aiding. When I drive off road at
an angle, the position will show as on the road until I'm about 100m off
of the road.

[Alan Browne]

The issue is "briefly". Tent material (unless metalized) is transparent
to the GPS signal so you will track perfectly there for as long as
you're under that cover, not just "briefly".

[Savageduck]

On 2013-04-28 07:52:03 -0700, Alan Browne

<alan....@FreelunchVideotron.ca> said:

> On 2013.04.28 10:39 , Savageduck wrote:
>> On 2013-04-28 06:21:24 -0700, Alan Browne
>> <alan....@FreelunchVideotron.ca> said:
>>
>>> On 2013.04.27 21:34 , Savageduck wrote:
>>>
>>>> After initial acquisition it performs well, even when briefly having
>>>> clear sky obscured by a tent, marquee, or tree cover. However heavy tree
>>>> cover can, and has interrupted the signal causing a failure to record
>>>> the data.
>>>
>>> A tent shouldn't affect GPS at all unless it has a metalic component.
>>
>> Agreed. As I stated above, the GP-1 performs well, even when briefly
>> having clear sky obscured by a tent.
>> The example shot I provided was shot in a tent.
>
> The issue is "briefly". Tent material (unless metalized) is
> transparent to the GPS signal so you will track perfectly there for as
> long as you're under that cover, not just "briefly".

Perhaps my use of "briefly" was a poor choice of words as I haven't
noticed a signal loss under that type of cover. However, heavy tree
cover has disrupted the signal enough to not get a four satellite fix
which is the minimum for the GP-1.

--
Regards,

Savageduck

[nospam]

In article <f-2dnfm8RsfPqODM...@giganews.com>, Alan Browne

<alan....@FreelunchVideotron.ca> wrote:

> >> It also outperforms (signal strength/processing grunt) my in-car GPS and
> >> my lowrance marine GPS by a mile (each of which cost much more than the
> >> phone).
> >
> >doubtful.
>
> It depends what he means by "outperform". If it means faster
> acquisition, he's right - but he'll have no idea how bad the quality of
> the solution is.

he said signal strength/processing grunt, whatever that means.

a smartphone might have a more capable processor (how many dedicated
gps units have a multicore cpu and gpu?), but that just makes for
pretty graphics and a responsive interface.

it says nothing about the radio, which is what matters.

> A marine GPS (like aviation) should be conservative. That results in
> slower acquisition, but better certainty about the quality of the
> solution. Since marine units operate in areas without much obstruction
> to the sky (typically) a conservative acquisition/tracking threshold is
> a good idea. Some marine units also allow you to enter the altitude of
> the surface you are on (lake elevation for example) and that gives you a
> "free" virtual satellite located at the center of the earth.
>
> (Indeed, if the altitude setting is used, but incorrect by a good bit,
> it will drag the position solution with it a good way unless RAIM is
> used to discard it. I don't believe any marine units use RAIM however).
>
> I don't have much of an opinion on automobile GPS sets. They seem to do
> well, but will occasionally show a wild error (show position on a
> parallel street 2 blocks away; or on the service road, etc.).
>
> Mine seems to use the map for position aiding. When I drive off road at
> an angle, the position will show as on the road until I'm about 100m off
> of the road.

i've never seen a 2 block error in a car, but have seen it lock to the
frontage road right next to the highway or vice versa. it's rarely an
issue since it's obvious what it should be and it quickly corrects
itself anyway.

[Me]

On 29/04/2013 2:42 a.m., Alan Browne wrote:
> On 2013.04.28 10:04 , nospam wrote:
>> In article <klj0ak$r93$1...@news.albasani.net>, Me <anywh...@here.com>
>> wrote:
>>
>>>> I use the Nikon GP-1 with my D300S. If my camera has been turned off
>>>> for
>>>> any considerable time, the GP-1 takes between 45 seconds to two minutes
>>>> to obtain initial Sat acquisition. Once that is done and I am
>>>> outdoors I
>>>> leave the camera on, and the additional battery drainage is negligible.
>>>> However I am using the Nikon MB-D10 grip + EN-EL4 battery.
>>>>
>>>> After initial acquisition it performs well, even when briefly having
>>>> clear sky obscured by a tent, marquee, or tree cover. However heavy
>>>> tree
>>>> cover can, and has interrupted the signal causing a failure to record
>>>> the data.
>>>
>>> This is nuts. My android phone has a GPS that takes a fraction of that
>>> time to acquire a fix (satellite only), heavy tree cover not a problem.
>>
>> smartphones use the cellular network to speed up the time to get a fix
>> and handle situations where gps reception is weak, such as under heavy
>> tree cover.

As I said, satellite only. Using cell tower "Google location service"
can be disabled, and in any case, either in my boat or in my car, I'm
frequently in places where there's no cellular service and no wifi, no
data service.
Sure - if using cell/wifi location services is enabled and within range,
then initial location fix is effectively instant (fix acquired by the
time the app is up and running), but with satellite only the phone is
much faster acquiring a new position fix than either dedicated GPS unit.
The new chipsets for phones are also combined glonass/gps receivers =
more satellites than gps alone.

>>
>> if cameras had cellular phones in them, they could do that too.
>>
>>> It also outperforms (signal strength/processing grunt) my in-car GPS and
>>> my lowrance marine GPS by a mile (each of which cost much more than the
>>> phone).
>>
>> doubtful.
>
> It depends what he means by "outperform". If it means faster
> acquisition, he's right - but he'll have no idea how bad the quality of
> the solution is.
>

How's that? If I can use two devices side by side, then surely that's a
pretty good indication. If the "quality of the solution" is
self-reported accuracy, then I can't see any difference. If it's
positional accuracy when zoomed in to a base map on a chart plotter,
then I can't see any difference either.
So I walk outside with my GPS phone on to my deck, zoom in with a google
satellite overlay, and it shows that I'm on the deck of my house,
reported accuracy 4m - but I presume that's maximum deviation, as it's
pinpointed my position within a metre.
But the phone outperforms each dedicated device in other ways. Battery
use is much lower, map loading is much faster, screen resolution is
higher with much faster refresh/scrolling, route calculation (using a
dedicated "off-line" car GPS app) is much faster.

>
> A marine GPS (like aviation) should be conservative. That results in
> slower acquisition, but better certainty about the quality of the
> solution. Since marine units operate in areas without much obstruction
> to the sky (typically) a conservative acquisition/tracking threshold is
> a good idea. Some marine units also allow you to enter the altitude of
> the surface you are on (lake elevation for example) and that gives you a
> "free" virtual satellite located at the center of the earth.
>
> (Indeed, if the altitude setting is used, but incorrect by a good bit,
> it will drag the position solution with it a good way unless RAIM is
> used to discard it. I don't believe any marine units use RAIM however).
>

I'm deeply suspicious that this is derived from marketing-speak/FUD
originating from dedicated GPS vendors.
For free, you can d/l the complete and official set of NZ and South
Pacific marine charts from the source, raster format, and use them on a
phone or tablet. GPS vendors used to bleed customers dry on prices for
the same maps formatted to work on their proprietary systems. Same for
the entire set of NZ topo maps. The apps I've looked at are a little
rough around the edges, but GPS accuracy and the maps themselves are not
the weak point.
I don't expect to see a commercial pilot or ship captain using a $US100
phone to navigate by, but I don't see any reason why an expensive
dedicated GPS unit needs to be used to geotag photos.

[Eric Stevens]

On Sun, 28 Apr 2013 11:04:10 +0100, Graham <gra...@INVALIDlodeway.com>
wrote:

>On Sun, 28 Apr 2013 12:37:51 +1200, Eric Stevens,
><news:s7ron853kp979mpoo...@4ax.com> expounded this
>theory:
>
>> I've been looking around and am disconcerted to find that all GPS
>> units seem to have a spotty reputation. Problems seem to include slow
>> satellite and position acquistion if the camera has been moved since
>> last time, errors in elevation, difficulty in crossing the equator
>> etc. Then there is their effect on battery life if you leave them
>> turned on.
>>
>> I know that only people with a grouch tend to write reviews but surely
>> they can't be as bad as I have read.
>>
>> I'm primarily looking for a GPS to tag my photographs so that 2 years
>> down the track I know which city I took them in. I need a fast start
>> up when I haul the camera out so that the rest of the mob has not
>> disappeared before my camera is ready to take a photograph.
>>
>> I will be using a Nikon D300 and will be interested in hearing of
>> other people's experience and comments.
>
>I use a Solmeta N3-A. I've had it for about two years and it has
>performed faultlessly.
>http://www.solmeta.com/index.php/Product/show/id/2

Now that looks interesting!

>
>I previously used a "Promote"
>http://www.promotesystems.com/products/Promote-GPS.html and it was
>almost useless, often failing to lock on for hours if at all.
>Eventually it stopped working altogether.
>
>Once the Solmeta has acquired the signal, which is fast, it is rock
>solid. Turn off the camera for an hour or so and the signal is
>re-acquired instantly. I'm more than happy with it.
>
--

Regards,

Eric Stevens

[Alan Browne]

"Self reported accuracy" in most consumer GPS's is in terms of (or
derived from) DOP (Dilution of Precision). That comes in flavours of
TDOP, PDOP, HDOP and VDOP (for time, position, horizontal and vertical).

The thing there is that it's based on "satellites in view" rather than
satellites actually being received and tracked. "in view" means "from
where you are, if there were no obsacles..."

> So I walk outside with my GPS phone on to my deck, zoom in with a google
> satellite overlay, and it shows that I'm on the deck of my house,
> reported accuracy 4m - but I presume that's maximum deviation, as it's
> pinpointed my position within a metre.

I can show you Google satellite views that are off by over 10 metres -
without even referencing a GPS. Take it with a grain of salt. That
said, Google sat views are very good - but not always, dependably so.

> But the phone outperforms each dedicated device in other ways. Battery
> use is much lower, map loading is much faster, screen resolution is
> higher with much faster refresh/scrolling, route calculation (using a
> dedicated "off-line" car GPS app) is much faster.

I plot WAAS GPS' v. the iPhone and the iPhone error is usually 5-20
metres v. true all-in-view/WAAS errors of 3 - 5 metres.

The iPhone GPS saves power by driving the correlators less often.
(Typical is 1 Hz, some GPS' go 10 or 20 or more. The iPhone is 0.5 Hz
or worse).

>>
>> A marine GPS (like aviation) should be conservative. That results in
>> slower acquisition, but better certainty about the quality of the
>> solution. Since marine units operate in areas without much obstruction
>> to the sky (typically) a conservative acquisition/tracking threshold is
>> a good idea. Some marine units also allow you to enter the altitude of
>> the surface you are on (lake elevation for example) and that gives you a
>> "free" virtual satellite located at the center of the earth.
>>
>> (Indeed, if the altitude setting is used, but incorrect by a good bit,
>> it will drag the position solution with it a good way unless RAIM is
>> used to discard it. I don't believe any marine units use RAIM however).
>>
> I'm deeply suspicious that this is derived from marketing-speak/FUD
> originating from dedicated GPS vendors.

What I wrote above is based on my intimate knowledge of GPS for various
markets. GPS was most used by mariners first because there were fewer
satellites - so the "free" satellite at the center of the earth (aka:
altitude above sea level) allowed mariners to use GPS with as few as 3
satellites in view: (2 real sats+altitude to determine position; 1
satellite more to determine receiver clock offset).

That said, accurate position and _integrity_ are important.

Laughably, the US DOD did not plan well for integrity in the original
signal specification so bolt on solutions like RAIM (internal) and
SBAS/GBAS (external) systems provide detection of "bad satellites" long
before the US DOD sends out a signal to ignore a satellite that's
outputting garbage. (In the US DOD scheme 4 hours or more could lapse
before the "bad" flag is set in the satellite status message - not
acceptable for commercial aviation).

> For free, you can d/l the complete and official set of NZ and South
> Pacific marine charts from the source, raster format, and use them on a
> phone or tablet. GPS vendors used to bleed customers dry on prices for
> the same maps formatted to work on their proprietary systems. Same for
> the entire set of NZ topo maps. The apps I've looked at are a little
> rough around the edges, but GPS accuracy and the maps themselves are not
> the weak point.

That has nothing to do with GPS sensors. You're talking about plotting
and mapping which really is not "GPS". It's navigation. Any nav source
will do (Omega/VLF, inertial, DME/DME, etc.). GPS is just the very
cheapest and accurate.

GPS accuracy does depend very much on implementation and conditions.

> I don't expect to see a commercial pilot or ship captain using a $US100
> phone to navigate by, but I don't see any reason why an expensive
> dedicated GPS unit needs to be used to geotag photos.

Shipboard GPS systems are integrated with plotters and the radar system,
position reporting, autopilot and so on. It's very sophisticated and in
someways laughably badly done - esp. the communications bus (bogged down
by legacy crap).

[Me]

On 29/04/2013 10:51 a.m., Alan Browne wrote:

>
> The thing there is that it's based on "satellites in view" rather than
> satellites actually being received and tracked. "in view" means "from
> where you are, if there were no obsacles..."
>

No. There's even a free android app "GPS essentials" which gives a
graphic positional chart, showing satellites that are in view, and of
those, which are in view which ones are used for tracking, and a
graphical representation of s/n ratio for each.

>
>> So I walk outside with my GPS phone on to my deck, zoom in with a google
>> satellite overlay, and it shows that I'm on the deck of my house,
>> reported accuracy 4m - but I presume that's maximum deviation, as it's
>> pinpointed my position within a metre.
>
> I can show you Google satellite views that are off by over 10 metres -
> without even referencing a GPS. Take it with a grain of salt. That
> said, Google sat views are very good - but not always, dependably so.

I'd like to know how systems like Google Earth allow for tectonic plate
movement.

>
>> But the phone outperforms each dedicated device in other ways. Battery
>> use is much lower, map loading is much faster, screen resolution is
>> higher with much faster refresh/scrolling, route calculation (using a
>> dedicated "off-line" car GPS app) is much faster.
>
> I plot WAAS GPS' v. the iPhone and the iPhone error is usually 5-20
> metres v. true all-in-view/WAAS errors of 3 - 5 metres.
>
> The iPhone GPS saves power by driving the correlators less often.
> (Typical is 1 Hz, some GPS' go 10 or 20 or more. The iPhone is 0.5 Hz
> or worse).
>

I'm not using an iPhone. GPS update interval is user-adjustable.

>
> Shipboard GPS systems are integrated with plotters and the radar system,
> position reporting, autopilot and so on. It's very sophisticated and in
> someways laughably badly done - esp. the communications bus (bogged down
> by legacy crap).
>

Yes - I was on a suction dredger a few weeks ago, made my way out on the
harbour pilot boat, accompanied by a tech from a marine instrument
company who was going to service some of their systems.
The systems were complex, I believe integrating sonar depth plotting -
the dredge head must be positioned accurately, taking into account tide
and the hopper load as they fill it. If they get it wrong, something
very expensive gets broken.

[Alan Browne]

On 2013.04.28 23:27 , Me wrote:
> On 29/04/2013 10:51 a.m., Alan Browne wrote:
>
>>
>> The thing there is that it's based on "satellites in view" rather
>> than satellites actually being received and tracked. "in view"
>> means "from where you are, if there were no obsacles..."
>>
> No. There's even a free android app "GPS essentials" which gives a
> graphic positional chart, showing satellites that are in view, and of
> those, which are in view which ones are used for tracking, and a
> graphical representation of s/n ratio for each.

Which goes to the estimated position but not to the estimate of
accuracy. This is an old issue with GPS receivers. The DOP's and URE
are based on "in view" and not on "tracked". But show me an app that
proves to do it differently and I'll be happy to look into it.

I just DL'd the "GPS Essentials" manual. It makes no mention of
fundamental GPS errors at all. No mention of the various DOP's. No
mention of FOM. No mention of URE. It does mention the 'used' / 'not
used' sats but it does not state _how_ it estimates accuracy.

(Note: the receiver device provides URE/FOM/DOP info so most apps won't
bother doing an independent estimate)

(No mention of WAAS, EGNOS or SBAS either)

S/N doesn't contribute much to accuracy unless the receiver is trying to
track well below recommended tracking thresholds. It would be nice if
there was a user setting for "conservative" v. "aggressive" acquisition
and tracking thresholds.

>>
>>> So I walk outside with my GPS phone on to my deck, zoom in with a
>>> google satellite overlay, and it shows that I'm on the deck of my
>>> house, reported accuracy 4m - but I presume that's maximum
>>> deviation, as it's pinpointed my position within a metre.
>>
>> I can show you Google satellite views that are off by over 10
>> metres - without even referencing a GPS. Take it with a grain of
>> salt. That said, Google sat views are very good - but not always,
>> dependably so.
> I'd like to know how systems like Google Earth allow for tectonic
> plate movement.

Google earth uses photos indexed to WGS-84, the same as GPS reference
system. But if the company providing a given photo didn't reference
it to WGS-84 correctly then there will be errors (as I've seen locally).

Plate movement is very slow. So slow that Google's continuous
replacement of aerial photos would more than account for it except where
there was a recent large shift.

Over time of course, the various constants in mapping systems that
relate _places_ to _geo-references_ will have to be updated. Esp. in
active regions such as Japan and California.

>>
>>> But the phone outperforms each dedicated device in other ways.
>>> Battery use is much lower, map loading is much faster, screen
>>> resolution is higher with much faster refresh/scrolling, route
>>> calculation (using a dedicated "off-line" car GPS app) is much
>>> faster.
>>
>> I plot WAAS GPS' v. the iPhone and the iPhone error is usually
>> 5-20 metres v. true all-in-view/WAAS errors of 3 - 5 metres.
>>
>> The iPhone GPS saves power by driving the correlators less often.
>> (Typical is 1 Hz, some GPS' go 10 or 20 or more. The iPhone is 0.5
>> Hz or worse).
>>
> I'm not using an iPhone. GPS update interval is user-adjustable.

There are plenty of GPS' with user settable _recording_ (or reporting)
rates, but that is not the GPS correlator _tracking_ loop rate. These
are different things.

Tracking loop rate is an internal thing to the device in the smartphone.
Some advanced GPS allow a user setting of 1 Hz, 2 Hz, 5Hz, 10 Hz, 20
Hz and so on tracking loop rates - but these are
configuration settings and typically not changeable without a re-start.
These are not very useful for hiking, but find their
place in inertial aiding and so on.

In the iPhone, to save power, they reduce the tracking rate. It's not
published, but looking at track recordings it's clear enough that the
rate is not better than 2 Hz. (And why it uses WiFi and cell towers for
"aiding").

>> Shipboard GPS systems are integrated with plotters and the radar
>> system, position reporting, autopilot and so on. It's very
>> sophisticated and in someways laughably badly done - esp. the
>> communications bus (bogged down by legacy crap).
>>
> Yes - I was on a suction dredger a few weeks ago, made my way out on
> the harbour pilot boat, accompanied by a tech from a marine
> instrument company who was going to service some of their systems.
> The systems were complex, I believe integrating sonar depth plotting
> - the dredge head must be positioned accurately, taking into account
> tide and the hopper load as they fill it. If they get it wrong,
> something very expensive gets broken.

I neglected to mention sonar - quite an important part of the plotter
integration to be sure - and not just for dredging. That also predates
GPS integration.

[PeterN]

On 4/27/2013 9:34 PM, Savageduck wrote:


<snip>

> So if you take one of my shots from that day:
> < http://db.tt/TtJ20HXK >
> and paste that URL into "Jeffery's EXIF Viewer" you should get this result.
> < http://regex.info/exif.cgi?imgurl=http%3A%2F%2Fdb.tt%2FTtJ20HXK >
>

OT Good abstraction.
i really like that capture. It has a nice ethereal, feel about it, with
strong contrasts. The highlights are not blown, nor are the dark areas
too muddy. I see strong lines and even a self portrait of the
photographer. Did you do any tone mapping?

--
PeterN

[Savageduck]

It is a 5 exposure HDR: -2, -1, 0, +1, +2, processed with NIK HDR Efex Pro.

--
Regards,

Savageduck

[PeterN]

I see it sits where the flash unit sits. Is there some mechanism that
would permit use of flash with the unit?

--
PeterN

[PeterN]

You would have if you were using my Garmin today. It told me to make a
turn just after I passed the exit. Despite claims to the contrary, I am
not convinced that selective Availability has been turned off.


--
PeterN

[Graham]

On Tue, 30 Apr 2013 18:32:21 -0400, PeterN,
<news:51804660$0$10793$8f2e...@news.shared-secrets.com> expounded
this theory:

> I see it sits where the flash unit sits. Is there some mechanism that
> would permit use of flash with the unit?

There is a clip supplied to attach it to a neck strap.

[PeterN]

On 4/30/2013 6:49 PM, Graham wrote:
> On Tue, 30 Apr 2013 18:32:21 -0400, PeterN,
> <news:51804660$0$10793$8f2e...@news.shared-secrets.com> expounded
> this theory:
>
>> I see it sits where the flash unit sits. Is there some mechanism that
>> would permit use of flash with the unit?
>
> There is a clip supplied to attach it to a neck strap.
>

Thanks, I thought there must be. I previously thought that I didn't need
one. I still don't need one, but I can see the attraction, and am
starting to think about getting one.

--
PeterN

[nospam]

In article <51804a04$0$10832$8f2e...@news.shared-secrets.com>, PeterN

<peter.n...@verizon.net> wrote:

> >> I don't have much of an opinion on automobile GPS sets. They seem to do
> >> well, but will occasionally show a wild error (show position on a
> >> parallel street 2 blocks away; or on the service road, etc.).
> >>
> >> Mine seems to use the map for position aiding. When I drive off road at
> >> an angle, the position will show as on the road until I'm about 100m off
> >> of the road.
> >
> > i've never seen a 2 block error in a car, but have seen it lock to the
> > frontage road right next to the highway or vice versa. it's rarely an
> > issue since it's obvious what it should be and it quickly corrects
> > itself anyway.
>
> You would have if you were using my Garmin today. It told me to make a
> turn just after I passed the exit.

missing an exit is not a 2 block error.

> Despite claims to the contrary, I am
> not convinced that selective Availability has been turned off.

it definitely has. anyone who thinks otherwise is confused.

[PeterN]

On 4/30/2013 8:30 PM, nospam wrote:
> In article <51804a04$0$10832$8f2e...@news.shared-secrets.com>, PeterN
> <peter.n...@verizon.net> wrote:
>
>>>> I don't have much of an opinion on automobile GPS sets. They seem to do
>>>> well, but will occasionally show a wild error (show position on a
>>>> parallel street 2 blocks away; or on the service road, etc.).
>>>>
>>>> Mine seems to use the map for position aiding. When I drive off road at
>>>> an angle, the position will show as on the road until I'm about 100m off
>>>> of the road.
>>>
>>> i've never seen a 2 block error in a car, but have seen it lock to the
>>> frontage road right next to the highway or vice versa. it's rarely an
>>> issue since it's obvious what it should be and it quickly corrects
>>> itself anyway.
>>
>> You would have if you were using my Garmin today. It told me to make a
>> turn just after I passed the exit.
>
> missing an exit is not a 2 block error.

Correct. It can be many miles.

My guess is that you do not use a GPS very often. The one in my iPhone
has Wakodahatchee in DelRay Beach, FL., about three blocks east of its
location. My iPhone GPS insisted that I drive through a swamp to get to
Zoo Miami. You don't have to believe me, look it up for yourself.

>
>> Despite claims to the contrary, I am
>> not convinced that selective Availability has been turned off.
>
> it definitely has. anyone who thinks otherwise is confused.
>

I find your reassurance comforting.

--
PeterN

[Eric Stevens]

Hand held? ... or did you use a tripod?
--

Regards,

Eric Stevens

[Savageduck]

Hand held.

--
Regards,

Savageduck

[nospam]

In article <51806b68$0$10781$8f2e...@news.shared-secrets.com>, PeterN

<peter.n...@verizon.net> wrote:

> >>>> I don't have much of an opinion on automobile GPS sets. They seem to do
> >>>> well, but will occasionally show a wild error (show position on a
> >>>> parallel street 2 blocks away; or on the service road, etc.).
> >>>>
> >>>> Mine seems to use the map for position aiding. When I drive off road at
> >>>> an angle, the position will show as on the road until I'm about 100m off
> >>>> of the road.
> >>>
> >>> i've never seen a 2 block error in a car, but have seen it lock to the
> >>> frontage road right next to the highway or vice versa. it's rarely an
> >>> issue since it's obvious what it should be and it quickly corrects
> >>> itself anyway.
> >>
> >> You would have if you were using my Garmin today. It told me to make a
> >> turn just after I passed the exit.
> >
> > missing an exit is not a 2 block error.
>
> Correct. It can be many miles.

you're so full of shit.

if you have a gps fix, it's definitely not off by 'many miles.'

if you don't have a gps fix, then your position can be anywhere. that's
what not having a gps fix means. wait until you actually do get a fix
before departing (plus, it takes longer to get a fix while moving too).

> My guess is that you do not use a GPS very often.

then you'd be wrong.

i often use a gps even when i know where i'm going because it knows
about traffic and also has an estimated time of arrival and has a more
accurate display of my current speed and distance travelled.

for road trips, i always use one.

> The one in my iPhone
> has Wakodahatchee in DelRay Beach, FL., about three blocks east of its
> location. My iPhone GPS insisted that I drive through a swamp to get to
> Zoo Miami. You don't have to believe me, look it up for yourself.

that's a map error, not a gps error.

in addition to apple's and google's maps, there are at least 7 gps apps
for the iphone that i can think of (navigon, tomtom, magellan, garmin,
copilot, motionx, waze), each of which has its own idea about what
roads are where and how to best route on them.

if one of those apps tells you to drive through a swamp then either
report the map error or switch to a different app (or both).

i also notice that you've switched from the garmin missed exit to the
iphone. what were you saying about bullshitting your way out?

> >> Despite claims to the contrary, I am
> >> not convinced that selective Availability has been turned off.
> >
> > it definitely has. anyone who thinks otherwise is confused.
>
> I find your reassurance comforting.

s/a was turned off may, 2000.

this is a fact that anyone can confirm.

it's without question, off.

[Savageduck]

Here is a non-HDR version.
< https://dl.dropbox.com/u/1295663/FileChute/DNC4143-Ew.jpg >

--
Regards,

Savageduck

[Eric Stevens]

On Tue, 30 Apr 2013 18:57:43 -0700, Savageduck

<savageduck1@{REMOVESPAM}me.com> wrote:

>On 2013-04-30 18:40:19 -0700, Eric Stevens <eric.s...@sum.co.nz> said:
>
>> On Tue, 30 Apr 2013 05:24:52 -0700, Savageduck
>> <savageduck1@{REMOVESPAM}me.com> wrote:
>>
>>> On 2013-04-30 05:00:27 -0700, PeterN <peter.n...@verizon.net> said:
>>>
>>>> On 4/27/2013 9:34 PM, Savageduck wrote:
>>>>
>>>>
>>>> <snip>
>>>>
>>>>> So if you take one of my shots from that day:
>>>>> < http://db.tt/TtJ20HXK >
>>>>> and paste that URL into "Jeffery's EXIF Viewer" you should get this result.
>>>>> < http://regex.info/exif.cgi?imgurl=http%3A%2F%2Fdb.tt%2FTtJ20HXK >
>>>>>
>>>>
>>>>
>>>> OT Good abstraction.
>>>> i really like that capture. It has a nice ethereal, feel about it, with
>>>> strong contrasts. The highlights are not blown, nor are the dark areas
>>>> too muddy. I see strong lines and even a self portrait of the
>>>> photographer. Did you do any tone mapping?
>>>
>>> It is a 5 exposure HDR: -2, -1, 0, +1, +2, processed with NIK HDR Efex Pro.
>>
>> Hand held? ... or did you use a tripod?
>
>Hand held.

Al I can say is that that is very good. It's a first rate example of
what HDR can do for poor lighting conditions with no (obvious) fancy
effects.
--

Regards,

Eric Stevens

[Eric Stevens]

On Tue, 30 Apr 2013 19:21:14 -0700, Savageduck

<savageduck1@{REMOVESPAM}me.com> wrote:

>On 2013-04-30 18:57:43 -0700, Savageduck <savageduck1@{REMOVESPAM}me.com> said:
>
>> On 2013-04-30 18:40:19 -0700, Eric Stevens <eric.s...@sum.co.nz> said:
>>
>>> On Tue, 30 Apr 2013 05:24:52 -0700, Savageduck
>>> <savageduck1@{REMOVESPAM}me.com> wrote:
>>>
>>>> On 2013-04-30 05:00:27 -0700, PeterN <peter.n...@verizon.net> said:
>>>>
>>>>> On 4/27/2013 9:34 PM, Savageduck wrote:
>>>>>
>>>>>
>>>>> <snip>
>>>>>
>>>>>> So if you take one of my shots from that day:
>>>>>> < http://db.tt/TtJ20HXK >
>>>>>> and paste that URL into "Jeffery's EXIF Viewer" you should get this result.
>>>>>> < http://regex.info/exif.cgi?imgurl=http%3A%2F%2Fdb.tt%2FTtJ20HXK >
>>>>>>
>>>>>
>>>>>
>>>>> OT Good abstraction.
>>>>> i really like that capture. It has a nice ethereal, feel about it, with
>>>>> strong contrasts. The highlights are not blown, nor are the dark areas
>>>>> too muddy. I see strong lines and even a self portrait of the
>>>>> photographer. Did you do any tone mapping?
>>>>
>>>> It is a 5 exposure HDR: -2, -1, 0, +1, +2, processed with NIK HDR Efex Pro.
>>>
>>> Hand held? ... or did you use a tripod?
>>
>> Hand held.
>
>Here is a non-HDR version.
>< https://dl.dropbox.com/u/1295663/FileChute/DNC4143-Ew.jpg >

Not of the same quality.
--

Regards,

Eric Stevens

[Savageduck]

There is a time and place for everything. HDR when used with restraint
can be a useful tool, as in this normal exposure vs 5 exposure HDR
comparison.
< http://db.tt/y5or9tBF >

--
Regards,

Savageduck

[PeterN]

On 4/30/2013 10:02 PM, nospam wrote:
> In article <51806b68$0$10781$8f2e...@news.shared-secrets.com>, PeterN
> <peter.n...@verizon.net> wrote:
>
>>>>>> I don't have much of an opinion on automobile GPS sets. They seem to do
>>>>>> well, but will occasionally show a wild error (show position on a
>>>>>> parallel street 2 blocks away; or on the service road, etc.).
>>>>>>
>>>>>> Mine seems to use the map for position aiding. When I drive off road at
>>>>>> an angle, the position will show as on the road until I'm about 100m off
>>>>>> of the road.
>>>>>
>>>>> i've never seen a 2 block error in a car, but have seen it lock to the
>>>>> frontage road right next to the highway or vice versa. it's rarely an
>>>>> issue since it's obvious what it should be and it quickly corrects
>>>>> itself anyway.
>>>>
>>>> You would have if you were using my Garmin today. It told me to make a
>>>> turn just after I passed the exit.
>>>
>>> missing an exit is not a 2 block error.
>>
>> Correct. It can be many miles.
>
> you're so full of shit.

Whoosh!

>
> if you have a gps fix, it's definitely not off by 'many miles.'
>
> if you don't have a gps fix, then your position can be anywhere. that's
> what not having a gps fix means. wait until you actually do get a fix
> before departing (plus, it takes longer to get a fix while moving too).

If the unit causes me to miss my exit, it still can take many mile to
recover. that is, unless you are one of those assholes who backs up on
an Interstate.

>
>> My guess is that you do not use a GPS very often.
>
> then you'd be wrong.
>
> i often use a gps even when i know where i'm going because it knows
> about traffic and also has an estimated time of arrival and has a more
> accurate display of my current speed and distance travelled.

Sounds important to me!

>
> for road trips, i always use one.
>

You must have a very good and intuitive system.
And I truly believe that someone with your intelligence would completely
rely on one, especially when you know the route.

>> The one in my iPhone
>> has Wakodahatchee in DelRay Beach, FL., about three blocks east of its
>> location. My iPhone GPS insisted that I drive through a swamp to get to
>> Zoo Miami. You don't have to believe me, look it up for yourself.
>
> that's a map error, not a gps error.
>
> in addition to apple's and google's maps, there are at least 7 gps apps
> for the iphone that i can think of (navigon, tomtom, magellan, garmin,
> copilot, motionx, waze), each of which has its own idea about what
> roads are where and how to best route on them.

Gee. I hadn't thought of that... What a great idea. If my ability to
find my desired location is impaired, just try another. Do I do so while
driving, or stop on a busy road, hoping I will get one of the lucky seven.

>
> if one of those apps tells you to drive through a swamp then either
> report the map error or switch to a different app (or both).
>
> i also notice that you've switched from the garmin missed exit to the
> iphone. what were you saying about bullshitting your way out?

Gee you are observant. If only you had comprehensive ability. But that
would be expecting too much.

>
>>>> Despite claims to the contrary, I am
>>>> not convinced that selective Availability has been turned off.
>>>
>>> it definitely has. anyone who thinks otherwise is confused.
>>
>> I find your reassurance comforting.
>
> s/a was turned off may, 2000.
>
> this is a fact that anyone can confirm.
>
> it's without question, off.
>

Yup!

--
PeterN

[PeterN]

I prefer the tone mapped version

--
PeterN

[PeterN]

As with any new tool, there is a tendency to overuse. The Harry Potter
effect that you seem to dislike is one example.



--
PeterN

[PeterN]

I see what you are trying to do. To my eye, the calm ocean in the
non-HDR version is more peaceful. I would have combined them.

--
PeterN

[nospam]

In article <5181312a$0$10806$8f2e...@news.shared-secrets.com>, PeterN

<peter.n...@verizon.net> wrote:

> > if you have a gps fix, it's definitely not off by 'many miles.'
> >
> > if you don't have a gps fix, then your position can be anywhere. that's
> > what not having a gps fix means. wait until you actually do get a fix
> > before departing (plus, it takes longer to get a fix while moving too).
>
> If the unit causes me to miss my exit, it still can take many mile to
> recover. that is, unless you are one of those assholes who backs up on
> an Interstate.

that's not the fault of the gps. that's you not paying attention.

a gps will give ample warning before an upcoming turn or exit and then
again closer to the actual turn. if you miss the exit, it's your fault.

hopefully, you don't endanger others in the process.

> >> My guess is that you do not use a GPS very often.
> >
> > then you'd be wrong.
> >
> > i often use a gps even when i know where i'm going because it knows
> > about traffic and also has an estimated time of arrival and has a more
> > accurate display of my current speed and distance travelled.
>
> Sounds important to me!

knowing about traffic is very important as is knowing exact speed,
unless you like getting tickets. car speedometers are not very
accurate.

> > for road trips, i always use one.
>
> You must have a very good and intuitive system.

i do.

> And I truly believe that someone with your intelligence would completely
> rely on one, especially when you know the route.

i don't rely on a gps at all. i *use* a gps as a navigational aid.

anyone who blindly follows a gps without using their brain deserves
what they get. expecting a gps to give perfect directions in all
situations is just asking for trouble.

that's how stuff like this happens:
<http://abcnews.go.com/blogs/headlines/2012/03/gps-tracking-disaster-jap
anese-tourists-drive-straight-into-the-pacific/>

<http://abcnews.go.com/Technology/gps-mishaps-trust-tech-leads-trouble/s
tory?id=10013723>

> >> The one in my iPhone
> >> has Wakodahatchee in DelRay Beach, FL., about three blocks east of its
> >> location. My iPhone GPS insisted that I drive through a swamp to get to
> >> Zoo Miami. You don't have to believe me, look it up for yourself.
> >
> > that's a map error, not a gps error.
> >
> > in addition to apple's and google's maps, there are at least 7 gps apps
> > for the iphone that i can think of (navigon, tomtom, magellan, garmin,
> > copilot, motionx, waze), each of which has its own idea about what
> > roads are where and how to best route on them.
>
> Gee. I hadn't thought of that...

now you do.

> What a great idea. If my ability to
> find my desired location is impaired, just try another. Do I do so while
> driving, or stop on a busy road, hoping I will get one of the lucky seven.

if you can't figure that out, then you deserve to get stuck in a swamp.

> > if one of those apps tells you to drive through a swamp then either
> > report the map error or switch to a different app (or both).
> >
> > i also notice that you've switched from the garmin missed exit to the
> > iphone. what were you saying about bullshitting your way out?
>
> Gee you are observant. If only you had comprehensive ability. But that
> would be expecting too much.

the only thing to expect are moronic insults from you.

> >>>> Despite claims to the contrary, I am
> >>>> not convinced that selective Availability has been turned off.
> >>>
> >>> it definitely has. anyone who thinks otherwise is confused.
> >>
> >> I find your reassurance comforting.
> >
> > s/a was turned off may, 2000.
> >
> > this is a fact that anyone can confirm.
> >
> > it's without question, off.
>
> Yup!

in other words, you admit you were lying.

[PeterN]

You have zero sarcastic radar.

>
>>> if one of those apps tells you to drive through a swamp then either
>>> report the map error or switch to a different app (or both).
>>>
>>> i also notice that you've switched from the garmin missed exit to the
>>> iphone. what were you saying about bullshitting your way out?
>>
>> Gee you are observant. If only you had comprehensive ability. But that
>> would be expecting too much.
>
> the only thing to expect are moronic insults from you.
>
>>>>>> Despite claims to the contrary, I am
>>>>>> not convinced that selective Availability has been turned off.
>>>>>
>>>>> it definitely has. anyone who thinks otherwise is confused.
>>>>
>>>> I find your reassurance comforting.
>>>
>>> s/a was turned off may, 2000.
>>>
>>> this is a fact that anyone can confirm.
>>>
>>> it's without question, off.
>>
>> Yup!
>
> in other words, you admit you were lying.
>

Never said that. What you don't seem to understand is that national
security needs have most likely found a workable substitute, so that
commercial use is more effective. It may not be called SA, but for
functional purposes, it will be effective.
Are you really dumb enough to believe everything the government says,
without questioning it. Well maybe you are.


--
PeterN

[Alan Browne]

On 2013.04.30 18:47 , PeterN wrote:

> I am
> not convinced that selective Availability has been turned off.

It's dead off by presidential directive (Clinton). Indeed the later
satellites don't even have the ability in software (and possibly in
hardware) to implement it.

In cities, larger errors can happen due to multipath in the urban
canyons of cities - so it's not unusual to have a block or 2 of error.

Other errors are due to bad databases, bad algorithms, the
realtime/share nature of smartphones (if that is the use case), poor
display realtime code and poor operator use.

I have had issues with older GPS's (pre-2000) where if the car radio was
turned up loud I'd occasionally get very bad errors on the GPS. Sudden
position swings of hundreds of km, velocity shown as 1000 km/hr and so
on. (Lowrance 12 receiver). But I haven't seen anything like that since.

[Alan Browne]

On 2013.05.01 16:00 , PeterN wrote:

> Never said that. What you don't seem to understand is that national
> security needs have most likely found a workable substitute, so that
> commercial use is more effective. It may not be called SA, but for
> functional purposes, it will be effective.

There is no need for SA at all. That is why it's not even set up on the
most recent satellites.

Prior to Clinton ordering the shutdown of SA there was a lot of testing
of military receivers ability to overcome jamming by virtue of L1/L2
tracking of the P/Y code portion of the GPS signal. In brief:

1. P/Y code has 10x the bandwidth and therefore is harder to jam than
C/A code.

2. There are two separate frequencies (L1 and L2) on military receivers,
so that much harder still (L1 and L2 is not just for improved accuracy).

3. Y-code is encrypted P code. Harder to spoof. Only military
receivers carry the W codes to decrypt it. The code changes every 7 days.

So when the military wants to deny C/A (Coarse/Acquisition - the code
that civil GPS receivers use) they can simply jam it enough to make it
difficult for the enemy to use. Or spoof it (locally, not from the GPS
sats) to cause large navigation errors for the enemy.

Meanwhile US, NATO and other "friendly" military users will be immune to
the jamming and spoofing as they'll be using all that "un jammed" bandwidth.

Some military systems will also have CRPA antennas that steer a null
towards the jamming source making it essentially "quiet" at the receiver.

[nospam]

In article <51817454$0$10762$8f2e...@news.shared-secrets.com>, PeterN

<peter.n...@verizon.net> wrote:

> >>>>>> Despite claims to the contrary, I am
> >>>>>> not convinced that selective Availability has been turned off.
> >>>>>
> >>>>> it definitely has. anyone who thinks otherwise is confused.
> >>>>
> >>>> I find your reassurance comforting.
> >>>
> >>> s/a was turned off may, 2000.
> >>>
> >>> this is a fact that anyone can confirm.
> >>>
> >>> it's without question, off.
> >>
> >> Yup!
> >
> > in other words, you admit you were lying.
> >
> Never said that.

yes it is. first you said you're not convinced it's off then you agree
that it has been off for 13 years.

> What you don't seem to understand is that national
> security needs have most likely found a workable substitute, so that
> commercial use is more effective. It may not be called SA, but for
> functional purposes, it will be effective.

keep trying to bullshit your way out.

> Are you really dumb enough to believe everything the government says,
> without questioning it. Well maybe you are.

i don't believe what the government says, but that's irrelevant.

s/a is off. end of story.

[Eric Stevens]

Harry Potter effect ... ?

That I seem to dislike ... ?

I'm sorry: I'm not with you.
--

Regards,

Eric Stevens

[PeterN]

i thought it was you who talked about not liking overdone HDR.
Here is some discussion of the Harry Potter effect.
<http://www.retouchpro.com/forums/photo-retouching/36336-harry-potter-posters-hdr.html>

For more, you can Google HDR "harry potter"



--
PeterN

[PeterN]

Thanks for that clear and reasonable explanation. I was referring to SA
in a generic sense, and had difficulty believing that there is no
difference between the military technology and its civilian equivalent.

--
PeterN

[Savageduck]

Worse than any "Harry Potter effect" would be the "Kinkade glow".


--
Regards,

Savageduck

[Eric Stevens]

On Wed, 01 May 2013 23:56:52 -0400, PeterN

It wasn't me complaining as far as I am aware, although I don't like
overdone HDR effects. I never use them when I use HDR. Nevertheless
the images can be spectacular when you get them right. They often look
wrong for the very simple reason they are not what the experienced
viewer expects a photo to look like. e.g.
https://dl.dropboxusercontent.com/u/31088803/_DSC5447_8_9_50_51_Detail.jpg
--

Regards,

Eric Stevens

[Savageduck]

Then there is always this type of thing:
< https://dl.dropbox.com/u/1295663/FileChute/DNC_0348_HDR-Ew.jpg >

--
Regards,

Savageduck

[Eric Stevens]

On Wed, 1 May 2013 23:46:06 -0700, Savageduck

It's a very nice image but my first reaction is that the colours are
slightly overdone. But is that a fair judgement?
--

Regards,

Eric Stevens

[PeterN]

That is one nice image. I consider it an example of one presented for
its artistic impact, as opposed to one presented simply because it can
be done.


--
PeterN

[PeterN]

On velvet.

--
PeterN

[PeterN]

A prime example of how to ruin a potentially nice image.


--
PeterN

[Alan Browne]

[Alan Browne]

On 2013.05.02 00:14 , PeterN wrote:

In the end the non-SA solution is much better since with SA it was
difficult to deny the enemy accuracy in, say Africa or Venezuela,
without affecting public users in the US or other friendly places. With
the local low altitude jam method you can affect a very small region.

I don't know for a fact, but I suspect certain C-130J's and EA-18's have
C/A code jam/spoof capability.

[PeterN]

I would hope so.

--
PeterN

[J. Clarke]

In article <51804a04$0$10832$8f2e...@news.shared-secrets.com>,
peter.n...@verizon.net says...
>
> On 4/28/2013 11:19 AM, nospam wrote:
> > In article <f-2dnfm8RsfPqODM...@giganews.com>, Alan Browne
> > <alan....@FreelunchVideotron.ca> wrote:
> >
> >>>> It also outperforms (signal strength/processing grunt) my in-car GPS and
> >>>> my lowrance marine GPS by a mile (each of which cost much more than the
> >>>> phone).
> >>>
> >>> doubtful.
> >>
> >> It depends what he means by "outperform". If it means faster
> >> acquisition, he's right - but he'll have no idea how bad the quality of
> >> the solution is.
> >
> > he said signal strength/processing grunt, whatever that means.
> >
> > a smartphone might have a more capable processor (how many dedicated
> > gps units have a multicore cpu and gpu?), but that just makes for
> > pretty graphics and a responsive interface.
> >
> > it says nothing about the radio, which is what matters.
> >
> >> A marine GPS (like aviation) should be conservative. That results in
> >> slower acquisition, but better certainty about the quality of the
> >> solution. Since marine units operate in areas without much obstruction
> >> to the sky (typically) a conservative acquisition/tracking threshold is
> >> a good idea. Some marine units also allow you to enter the altitude of
> >> the surface you are on (lake elevation for example) and that gives you a
> >> "free" virtual satellite located at the center of the earth.
> >>
> >> (Indeed, if the altitude setting is used, but incorrect by a good bit,
> >> it will drag the position solution with it a good way unless RAIM is
> >> used to discard it. I don't believe any marine units use RAIM however).

> >>
> >> I don't have much of an opinion on automobile GPS sets. They seem to do
> >> well, but will occasionally show a wild error (show position on a
> >> parallel street 2 blocks away; or on the service road, etc.).
> >>
> >> Mine seems to use the map for position aiding. When I drive off road at
> >> an angle, the position will show as on the road until I'm about 100m off
> >> of the road.
> >
> > i've never seen a 2 block error in a car, but have seen it lock to the
> > frontage road right next to the highway or vice versa. it's rarely an
> > issue since it's obvious what it should be and it quickly corrects
> > itself anyway.
> >
>
> You would have if you were using my Garmin today. It told me to make a

> turn just after I passed the exit. Despite claims to the contrary, I am

> not convinced that selective Availability has been turned off.

That's more likely to be a map error. Try the same route another time
and see if it does it again. The maps aren't perfect. One of my
favorites is the time it told me to turn left onto an on-ramp, which
would require that I cross a median, a guard rail, and four lanes of
oncoming traffic, then climb an embankment. When I finally got to the
real on-ramp I could see where there used to be another one where it was
telling me to turn. Another is the time that I was following its
directions and the road was first nicely paved, then got somewhat
dilapidated, then turned to gravel, then dirt, then a cowpath, and the
cowpath finally came to a hole cut in a chain-link fence. At that point
I decided to backtrack and look for an alternate route.

[Eric Stevens]

On Mon, 29 Apr 2013 10:07:53 +1200, Eric Stevens
<eric.s...@sum.co.nz> wrote:

>On Sun, 28 Apr 2013 11:04:10 +0100, Graham <gra...@INVALIDlodeway.com>
>wrote:
>
>>On Sun, 28 Apr 2013 12:37:51 +1200, Eric Stevens,
>><news:s7ron853kp979mpoo...@4ax.com> expounded this
>>theory:
>>
>>> I've been looking around and am disconcerted to find that all GPS
>>> units seem to have a spotty reputation. Problems seem to include slow
>>> satellite and position acquistion if the camera has been moved since
>>> last time, errors in elevation, difficulty in crossing the equator
>>> etc. Then there is their effect on battery life if you leave them
>>> turned on.
>>>
>>> I know that only people with a grouch tend to write reviews but surely
>>> they can't be as bad as I have read.
>>>
>>> I'm primarily looking for a GPS to tag my photographs so that 2 years
>>> down the track I know which city I took them in. I need a fast start
>>> up when I haul the camera out so that the rest of the mob has not
>>> disappeared before my camera is ready to take a photograph.
>>>
>>> I will be using a Nikon D300 and will be interested in hearing of
>>> other people's experience and comments.
>>
>>I use a Solmeta N3-A. I've had it for about two years and it has
>>performed faultlessly.
>>http://www.solmeta.com/index.php/Product/show/id/2
>
>Now that looks interesting!

The Solmeta N3-A has arrived and once it stopped raining I went out
into the yard to set it up. It acquired a lock-on within a few seconds
of me turning it on, even before I calibrated it. I decided I had
better calibrate it and went out into an area of concrete and once I
did the required 'rotate it two times for each of the X, Y and Z
axiis', it mumbled to itself for about 10 seconds and reported a lock.

At that point I immediately took 4 shots to the N, E, S and West, and
went inside and downloaded them all to the computer using Nikon
Transfer. Nikon Transfer then called up View NX2. At this point I
clicked the Geo Tag button and within a few seconds I was staring at a
Google map indicating almost exactly where I had stood when I took the
first photograph. The only thing that was squiffy was that it had my
altitude at 33m when I was closer to 19m, but that is almost to be
expected. The altitude accuracy may improve if I give it more time to
refine it's fix.


>>I previously used a "Promote"
>>http://www.promotesystems.com/products/Promote-GPS.html and it was
>>almost useless, often failing to lock on for hours if at all.
>>Eventually it stopped working altogether.
>>
>>Once the Solmeta has acquired the signal, which is fast, it is rock
>>solid. Turn off the camera for an hour or so and the signal is
>>re-acquired instantly. I'm more than happy with it.
>>
--

Regards,

Eric Stevens

[Savageduck]

Have fun!

>>> I previously used a "Promote"
>>> http://www.promotesystems.com/products/Promote-GPS.html and it was
>>> almost useless, often failing to lock on for hours if at all.
>>> Eventually it stopped working altogether.
>>>
>>> Once the Solmeta has acquired the signal, which is fast, it is rock
>>> solid. Turn off the camera for an hour or so and the signal is
>>> re-acquired instantly. I'm more than happy with it.


--
Regards,

Savageduck

[Graham]

On Wed, 15 May 2013 14:54:02 +1200, Eric Stevens,
<news:b1t5p85c4kfrk9721...@4ax.com> expounded this
theory:

>>>I use a Solmeta N3-A. I've had it for about two years and it has
>>>performed faultlessly.
>>>http://www.solmeta.com/index.php/Product/show/id/2
>>
>>Now that looks interesting!
>
> The Solmeta N3-A has arrived and once it stopped raining I went out
> into the yard to set it up. It acquired a lock-on within a few seconds
> of me turning it on, even before I calibrated it. I decided I had
> better calibrate it and went out into an area of concrete and once I
> did the required 'rotate it two times for each of the X, Y and Z
> axiis', it mumbled to itself for about 10 seconds and reported a lock.
>
> At that point I immediately took 4 shots to the N, E, S and West, and
> went inside and downloaded them all to the computer using Nikon
> Transfer. Nikon Transfer then called up View NX2. At this point I
> clicked the Geo Tag button and within a few seconds I was staring at a
> Google map indicating almost exactly where I had stood when I took the
> first photograph. The only thing that was squiffy was that it had my
> altitude at 33m when I was closer to 19m, but that is almost to be
> expected. The altitude accuracy may improve if I give it more time to
> refine it's fix.

That's a relief, I'm glad you like it.

--
Graham
Comments and criticism welcome
http://www.lodeway.com

[Alan Browne]

On 2013.05.14 22:54 , Eric Stevens wrote:

> first photograph. The only thing that was squiffy was that it had my
> altitude at 33m when I was closer to 19m, but that is almost to be
> expected. The altitude accuracy may improve if I give it more time to
> refine it's fix.

Not really. The 14m vertical error you have there sounds pretty typical.

Altitude error in GPS is about 2x the horizontal error. This is because
the GPS sats providing the most altitude accuracy are above the receiver
and there are no "opposing" satellite signals contributing (below your
feet). (Horizontally, there are satellites distributed somewhat evenly
in all directions).

So where you should expect 5 - 10 metre horizontal accuracy with a good
view of the sky, in the same conditions, 10 - 20 metre vertical accuracy
would be expected.

If the GPS receiver is SBAS correcting (WAAS/EGNOS/MSAS) then you can
approximately halve those numbers -if- the receiver was receiving SBAS
at the time.

Then: What was your source for "19m"?

The point is that the WGS-84 (your GPS) ellipsoid has little to do with
the altitude you will get off of a topo map (Geoid (sea level where you
are)) or Google Earth (various, mostly satellite radar measured wrt the
geoid (ish)).

But the elevation of the ellipsoid is a mathematical estimate that does
not coincide well with the Geoid (sea level where you're at) and this
results in altitude differences of ~ - 100 to + 100 m depending on where
you are (values closer to 0 are more typical - where I am the Geoid is
about 31 m below the WGS-84 elipsoid). Some receivers may have a
geoid/elipsoid correction but I doubt yours does.

[Eric Stevens]

On Thu, 16 May 2013 16:00:44 +0100, Graham <gra...@INVALIDlodeway.com>
wrote:

The weather has been far too grim for me to go out trying the device
but the indications are that it's going to be a valuable adjunct to my
camera. It seems to be both better and cheaper than the Nikon item.
Time will tell.

I'm very grateful to you for telling me about it.
--

Regards,

Eric Stevens

[Eric Stevens]

On Thu, 16 May 2013 17:31:30 -0400, Alan Browne
<alan....@FreelunchVideotron.ca> wrote:

>On 2013.05.14 22:54 , Eric Stevens wrote:
>
>> first photograph. The only thing that was squiffy was that it had my
>> altitude at 33m when I was closer to 19m, but that is almost to be
>> expected. The altitude accuracy may improve if I give it more time to
>> refine it's fix.
>
>Not really. The 14m vertical error you have there sounds pretty typical.
>
>Altitude error in GPS is about 2x the horizontal error. This is because
>the GPS sats providing the most altitude accuracy are above the receiver
>and there are no "opposing" satellite signals contributing (below your
>feet). (Horizontally, there are satellites distributed somewhat evenly
>in all directions).
>
>So where you should expect 5 - 10 metre horizontal accuracy with a good
>view of the sky, in the same conditions, 10 - 20 metre vertical accuracy
>would be expected.
>
>If the GPS receiver is SBAS correcting (WAAS/EGNOS/MSAS) then you can
>approximately halve those numbers -if- the receiver was receiving SBAS
>at the time.
>
>Then: What was your source for "19m"?

The GIS data provided by the Auckland City Council.

>
>The point is that the WGS-84 (your GPS) ellipsoid has little to do with
>the altitude you will get off of a topo map (Geoid (sea level where you
>are)) or Google Earth (various, mostly satellite radar measured wrt the
>geoid (ish)).
>
>But the elevation of the ellipsoid is a mathematical estimate that does
>not coincide well with the Geoid (sea level where you're at) and this
>results in altitude differences of ~ - 100 to + 100 m depending on where
>you are (values closer to 0 are more typical - where I am the Geoid is
>about 31 m below the WGS-84 elipsoid). Some receivers may have a
>geoid/elipsoid correction but I doubt yours does.
--

Regards,

Eric Stevens

[Alan Browne]

On 2013.05.16 21:11 , Eric Stevens wrote:
> On Thu, 16 May 2013 17:31:30 -0400, Alan Browne
> <alan....@FreelunchVideotron.ca> wrote:
>
>> On 2013.05.14 22:54 , Eric Stevens wrote:
>>
>>> first photograph. The only thing that was squiffy was that it had my
>>> altitude at 33m when I was closer to 19m, but that is almost to be
>>> expected. The altitude accuracy may improve if I give it more time to
>>> refine it's fix.
>>
>> Not really. The 14m vertical error you have there sounds pretty typical.
>>
>> Altitude error in GPS is about 2x the horizontal error. This is because
>> the GPS sats providing the most altitude accuracy are above the receiver
>> and there are no "opposing" satellite signals contributing (below your
>> feet). (Horizontally, there are satellites distributed somewhat evenly
>> in all directions).
>>
>> So where you should expect 5 - 10 metre horizontal accuracy with a good
>> view of the sky, in the same conditions, 10 - 20 metre vertical accuracy
>> would be expected.
>>
>> If the GPS receiver is SBAS correcting (WAAS/EGNOS/MSAS) then you can
>> approximately halve those numbers -if- the receiver was receiving SBAS
>> at the time.
>>
>> Then: What was your source for "19m"?
>
> The GIS data provided by the Auckland City Council.

The difference between the Geoid and WGS-84 Ellipsoid is 33.75 m at
Aukland. eg: a GPS will determine the elevation as 33.75m too high.

Actual elevation (per you): 19m
GPS Geoid + 33.75
= 52.75 <- what your GPS _should_ have
said for 0 error.

GPS reading: 33
Error: -19.75 metres.

Unless your GPS corrected for it, in which case your error was 14m (!).

>>
>> The point is that the WGS-84 (your GPS) ellipsoid has little to do with
>> the altitude you will get off of a topo map (Geoid (sea level where you
>> are)) or Google Earth (various, mostly satellite radar measured wrt the
>> geoid (ish)).
>>
>> But the elevation of the ellipsoid is a mathematical estimate that does
>> not coincide well with the Geoid (sea level where you're at) and this
>> results in altitude differences of ~ - 100 to + 100 m depending on where
>> you are (values closer to 0 are more typical - where I am the Geoid is
>> about 31 m below the WGS-84 elipsoid). Some receivers may have a
>> geoid/elipsoid correction but I doubt yours does.


--

[Graham]

On Fri, 17 May 2013 13:08:38 +1200, Eric Stevens,
<news:gk0bp8pgp1ri6djbe...@4ax.com> expounded this
theory:

> The weather has been far too grim for me to go out trying the device
> but the indications are that it's going to be a valuable adjunct to my
> camera. It seems to be both better and cheaper than the Nikon item.
> Time will tell.
>
> I'm very grateful to you for telling me about it.

I might have bee a bit too quick in recommending it, I've just
received this info about a "new improved" model. I might have to
upgrade.

<http://news.gps-camera.eu/show_mailing.php?id=6000611&h=32248-7fd8897c5eb6ad9c2880ebab8bb7a638>

Google will translate.

[PeterN]

so far it's a candidate. It wold be nice to know where the images camefrom.

--
PeterN

[Alan Browne]

On 2013.05.16 21:11 , Eric Stevens wrote:

> On Thu, 16 May 2013 17:31:30 -0400, Alan Browne

>> If the GPS receiver is SBAS correcting (WAAS/EGNOS/MSAS) then you can
>> approximately halve those numbers -if- the receiver was receiving SBAS
>> at the time.
>>
>> Then: What was your source for "19m"?
>
> The GIS data provided by the Auckland City Council.

I dug into the spec of your receiver. It uses the MTK MT3329 receiver
which is an SBAS receiving device. (No surprise - most receivers are
these days).

However, I forgot to mention in the prior post that SBAS does not cover NZ.

Your receiver might pick up MSAS (Japan's SBAS) but the corrections
don't map NZ - some of the data may be helpful to the receiver (PR
corrections for most of the satellites received and integrity). A
future Japanese SBAS system (QZSS) will cover Australia and NZ from
about 2017 or so.

So for the present, in open sky (to the horizon + 10 deg.) conditions,
you should expect 5 - 10 metre horizontal accuracy most of the time; and
10 - 20 metre vertical accuracy.

Which for the purpose of ground photo tagging is more than sufficient.

[Eric Stevens]

On Thu, 16 May 2013 21:39:45 -0400, Alan Browne

"I don't want to know that!"

I thought these things were supposed to make life simple. :-(

>
>>>
>>> The point is that the WGS-84 (your GPS) ellipsoid has little to do with
>>> the altitude you will get off of a topo map (Geoid (sea level where you
>>> are)) or Google Earth (various, mostly satellite radar measured wrt the
>>> geoid (ish)).
>>>
>>> But the elevation of the ellipsoid is a mathematical estimate that does
>>> not coincide well with the Geoid (sea level where you're at) and this
>>> results in altitude differences of ~ - 100 to + 100 m depending on where
>>> you are (values closer to 0 are more typical - where I am the Geoid is
>>> about 31 m below the WGS-84 elipsoid). Some receivers may have a
>>> geoid/elipsoid correction but I doubt yours does.
--

Regards,

Eric Stevens

[Alan Browne]

On 2013.05.17 17:48 , Eric Stevens wrote:
> On Thu, 16 May 2013 21:39:45 -0400, Alan Browne

>>>> Then: What was your source for "19m"?
>>>
>>> The GIS data provided by the Auckland City Council.
>>
>> The difference between the Geoid and WGS-84 Ellipsoid is 33.75 m at
>> Aukland. eg: a GPS will determine the elevation as 33.75m too high.
>>
>> Actual elevation (per you): 19m
>> GPS Geoid + 33.75
>> = 52.75 <- what your GPS _should_ have
>> said for 0 error.
>>
>> GPS reading: 33
>> Error: -19.75 metres.
>>
>> Unless your GPS corrected for it, in which case your error was 14m (!).
>
> "I don't want to know that!"
>
> I thought these things were supposed to make life simple. :-(

They do. But they don't do miracles.

[Eric Stevens]

Many thanks.

... the things you have to know to use a digital camera. :-(
--

Regards,

Eric Stevens

[Alan Browne]

On 2013.05.17 22:42 , Eric Stevens wrote:
> On Fri, 17 May 2013 17:35:20 -0400, Alan Browne

>> Which for the purpose of ground photo tagging is more than sufficient.
>
> Many thanks.
>
> ... the things you have to know to use a digital camera. :-(

I'd think the more useful thing to know is: turn on your GPS about 5
minutes before entering a heavily wooded area and leave it on. Once
under heavy canopy it's ability to lock on to lower elevation satellites
will be compromised and the position accuracy will be poor.

That really is the one thing you should take care about.

[Eric Stevens]

On Sat, 18 May 2013 10:38:22 -0400, Alan Browne
<alan....@FreelunchVideotron.ca> wrote:

>On 2013.05.17 22:42 , Eric Stevens wrote:
>> On Fri, 17 May 2013 17:35:20 -0400, Alan Browne
>
>>> Which for the purpose of ground photo tagging is more than sufficient.
>>
>> Many thanks.
>>
>> ... the things you have to know to use a digital camera. :-(
>
>
>I'd think the more useful thing to know is: turn on your GPS about 5
>minutes before entering a heavily wooded area and leave it on. Once
>under heavy canopy it's ability to lock on to lower elevation satellites
>will be compromised and the position accuracy will be poor.
>
>That really is the one thing you should take care about.

Fortunately I'm not trying to navigate or carry out a survey with the
device. All I want is the ready ability to determine whether a
photograph was taken in Lubeck or Gydnia. :-)
--

Regards,

Eric Stevens

[Alan Browne]

Fair enough. I tend to want to get the best out of the GPS. But also
bear in mind that once you enter the woods it can take a long time for
it to lock - it's not just accuracy but simply the ability to track
enough sats to get a position - no matter how bad. So you may want to
shoot something but the GPS isn't ready. You'll just have to remember
that one or perhaps tag it after the fact with one of the free utilities
(or EXIFTOOL).

I may seem obsessive on these points but I do a lot GPS recording for
various reasons and so observe the thing close hand.