The time of photography

[Евгений Вельдяев]

Hi
I was surprised at the time it was pointed at my panoramas, like the
time of photography.
It was 5 hours later than real time when the photo was taken.
At first I thought it made a wrong camera settings. Checked the
camera, it turned out all right.
Then I counted my local time to Greenwich Meridian Time (GMT). But in
this case, from my local time should be deducted 5 hours, since my
time zone is ahead of London time is 5 hours.
So I think that the time of photographing the site indicated with an
error.
Sorry for bad English. I hope that my thoughts are clear.
Evgeniy.

[Booking.Buchung]

I understando your english but I am not able to understand of what about you
are talking.

Best regards.

[Geoff - Spherical Visions]

Have you set up the location of your account correctly ?

Is the TimeZone information on the Image correct ?

[Евгений Вельдяев]

Yes, I correctly pointed out my location.
My time zone GMT +5.
But the shooting indicated five hours later.
http://www.360cities.net/image/sverdlov-street-33-ozersk
Here, for example, shows the time 20:58. And actually I was
photographing at 15:58.
If the site shows the time GMT, then we must show 10:58

Sincerely, Evgeniy

On 16 мар, 21:46, Geoff - Spherical Visions <geoff.mat...@gmail.com>
wrote:

> Have you set up the location of your account correctly ?
>

> <https://lh4.googleusercontent.com/_kcfqmKyJPr4/TYDoexiw-XI/AAAAAAAAAC...>

>
> Is the TimeZone information on the Image correct ?
>

> <https://lh3.googleusercontent.com/_kcfqmKyJPr4/TYDpM_1_OUI/AAAAAAAAAC...>

[Jan Vrsinsky | Product Manager, 360cities.net]

Hi

Can you send a screenshot? For me it shows 15:58.

Jan

[kfj]

Am Mittwoch, 16. März 2011 16:38:26 UTC+1 schrieb Евгений Вельдяев:

Hi
I was surprised at the time it was pointed at my panoramas, like the
time of photography.
It was 5 hours later than real time when the photo was taken.

I have the same problem. My camera is a Canon EOS 450D. I set it to local time, which is GMT+2 (it's summer, so this is DST, and I'm in central Europe). The images have local time timestamps, exiftool tells me, for example:

Date/Time Original              : 2012:07:09 18:37:08.03

my GPS unit (etrex vista hcx) is set to Central Europe with a UTC offset of +1:00 and DST auto. Geotagging the images from the GPX tracks works just fine, so the camera, the GPS and my computer seem to agree on the time, and the GPS unit certainly knows precisely what the time is. When I upload the panorama to 360cities, the time comes out as 20:37:08, as if I had my camera and GPS unit set to GMT. My account is set up with a location in the same time zone (I haven't found a place to set the time zone, so I assume it's calculated from my position), and 360cities displays the time as 'GMT2', but it has obviously taken the 'date/time original' and added two hours to it.

Why do I care? I just came up with a neat trick to orient my panoramas. If I have the sun visible in the panorama, I enter the date/time and position into Wolfram Alpha, like this:

sun July 9 2012 18:37 at 45.338 N 7.2524 E

after a bit of trundling and the assumption that I mean the sun as a celestial body, it tells me, among other stuff, that the azimuth is 275.9, which is the number I need to enter in the orientation dialog when the sun is in the center. Wolfram Alpha takes the time as CEST and acknowledges DST automatically (since it knows the precise location from the coordinates it can infer the time zone, and since it has the date it can figure out if it's DST or not)

I wonder what to do now. I certainly don't want to manually reset the time for all my 150 or so panoramas. After all the timestamps are correct. Any ideas?

Kay

 

[Geoff - Spherical Visions]

As far as I am aware the EXIF standard doesn't handle Timezones, hence the timezone stamp has to be "guessed" from other relevant info. or non-standard fields, not all systems get it right :-(
See here for some more info http://u88.n24.queensu.ca/exiftool/forum/index.php/topic,3323.msg14982.html#msg14982

[kfj]

Am Donnerstag, 2. August 2012 21:57:07 UTC+2 schrieb Geoff - Spherical Visions:

As far as I am aware the EXIF standard doesn't handle Timezones, hence the timezone stamp has to be "guessed" from other relevant info. or non-standard fields, not all systems get it right :-(
See here for some more info http://u88.n24.queensu.ca/exiftool/forum/index.php/topic,3323.msg14982.html#msg14982

I have the feeling that 360cities' guess is wrong. All the tools in my toolchain agree upon the time in the images, but 360cities insists on adding two hours to the time in the file. Is there any documentation which EXIF tag 360cities examines and what it does to establish the time at which the image was taken from this tag? If it is mandatory to hand in UTC-time-tagged images to get a correct result, I'd like to be pointed to the documentation dealing with this issue. Let me add I'm using a Linux system (Kubuntu 11.4 on 32bit intel), just in case this may help to find the problem.

[elena.martinez]

Hello kfj,

We are checking your issue. I'll let you know when I have any information.

Regards,

Elena

[Gerardo - 360Cities]

We do try to extract the timezone information when available, but the timezone is not always present in the exif data.

For example, this is the exif information available on one of Kay's images:

Date/Time Original              : 2012:07:09 18:37:08

Create Date                     : 2012:07:09 18:37:08

There is no timezone information in those tags. In these cases, when no timezone information is available in the exif data, we assume the timezone to be UTC.

To answer the question of what tags do we use to determine the time and date on which the panorama was taken, we inspect Create Date first, and if it is not available or empty, we inspect Date/Time Original.

[Geoff - Spherical Visions]

Would it also be worth checking GPSTime or GPSDateTime as these are ALWAYS UTC, this could then be combined with the the TimeZone recorded for the User (OK User may have moved between Timezones just to confuse of course!)

[Kay F. Jahnke]

Am 03.08.2012 16:08, schrieb Gerardo - 360Cities:

> We do try to extract the timezone information when available, but the
> timezone is not always present in the exif data.
>
> For example, this is the exif information available on one of Kay's images:
>
> Date/Time Original : 2012:07:09 18:37:08
> Create Date : 2012:07:09 18:37:08
>
> There is no timezone information in those tags. In these cases, when no
> timezone information is available in the exif data, we assume the
> timezone to be UTC.

How would the exif information look if time zone information was in
them? And what tool would I use to add the time zone information to the
exif tags? Can you give a sample exiftool call to get this done? If I
include a suffix like '+02:00' in a call to exiftool to set the
date/time original, it has no effect, only when I modify the create
date. I'd say all the file dates are the OS's business and may mean all
kinds of things, but I'd only resort to them if no exif data can be found.

I feel it's wrong to assume UTC when there is no time zone information.
I think the most obvious guess would be that the time in the exif data
is local time, and if I as the author give a time without timezone
information, I'd expect this time to be shown to the public. Whatever
the content of the tag, it should be interpreted as the information I
intend to have published and not as somthing I am unaware of which needs
processing your end. If I add a time zone, the viewer can display the
timezone information, if I don't, it should just display what it finds
in the tag. Moreover, it is quite irrelevant what time it was at the
viewer's location when the image was taken.

If I upload an image with a time tag of '18:00' and no further
information (like a time zone, however this might be accomplished), I
would expect the site to present my image as taken at the time I have
put into the tag and not at a time generated by

a) the assumption 18:00 is 18:00 UTC
b) the addition of two hours because my (the viewer's) timezone is CEST

which results in a display of 20:00.

If you want to do any trickery along those lines, have a look at the GPS
time stamp, if present (like in my images). The GPS time stamp is, as
far as I know, always UTC.

> To answer the question of what tags do we use to determine the time and
> date on which the panorama was taken, we inspect Create Date first, and
> if it is not available or empty, we inspect Date/Time Original.

I'd say this is debatable: in a panorama date/time original seems the
more obvious choice. The create date may be carried over from the
initial images, or it may not - it might be the moment the panorama
software writes it's product (which is, in fact, the create time of the
panorama), or it may even be some later stage's timestamp.

Thanks for looking into the matter. I hope you'll find a good solution.
I know metadata is a terribly tricky affair, but I think my suggestion
is feasible:

- use date/time original or create time if available
- if no timezone is given, don't try and guess it
- don't adapt the time to the user's timezone
- display the time as given, with or without timezone

This procedure should be straightforward, as it makes no assumptions,
and should produce a result which is preceived as being obvious. Keep it
simple. Trust the user.

[kfj]

Am Freitag, 3. August 2012 16:41:19 UTC+2 schrieb Geoff - Spherical Visions:

Would it also be worth checking GPSTime or GPSDateTime as these are ALWAYS UTC, this could then be combined with the the TimeZone recorded for the User (OK User may have moved between Timezones just to confuse of course!)

I think the time zone recorded for the user is quite irrelevant. I know people taking images outside their home timezone ;-)

I also thought of looking into GPSTime, I just don't know if it's always set. If it's always set in a geotagged image (assuming noone deliberately deletes it), it could be used together with the GPS location information to calculate the timezone the image was taken in, and from that the local time, which should be displayed. This sounds like a checkup method: if the uploaded pano has GPSTime set and the calculated timezone indicates a local time different from the date/time original, a popup message could ask if maybe something is amiss and offer to use the time derived from GPS time and location instead, like 'are you sure 17:53 is right? GPS data indicate local time was 18:53'

I use a separate GPS unit. This unit has many more uses than just recording the position to geotag my images: it shows me where I am, what time it is (local time, of course - I'm not so interested at what UTC time the sun sets), what's around me, not to mention altitude, ground speed etc. etc. I would not want to operate the GPS unit and the camera on UTC. So geotagging is just one function of the device, and while I'm out there, I don't even care so much about the geotagging, but more about recording my trail. Things may be different for people who have cameras with built-in GPS units.

Kay

[Evgeniy Veldyaev]

I agree with all your suggestions.

пятница, 3 августа 2012 г., 22:57:40 UTC+6 пользователь kfj написал:

[elena.martinez]

Hello,

Thank you very much for all your suggestions.

Regards,

Elena