Tripod Removal with HDR's

[cubicle]

For HDR images, is it necessary to remove the tripod in all 3
exposures or can I do so in the only the optimal exposure and then
simply utilize that image (rather than all three)?

Removing the tripod only once would obviously save a lot of time but
will the coloring be off if I don't remain consistent? That is to
say, will the colouring be off if I use HDRs for everything with the
exception of the nadir which uses only a single exposure?

[Erik Krause]

Am 24.06.2010 22:13, schrieb cubicle:
> For HDR images, is it necessary to remove the tripod in all 3
> exposures or can I do so in the only the optimal exposure and then
> simply utilize that image (rather than all three)?

If you mean masking the tripod with an alpha channel - Yes, you need to
do it in all exposure steps. If you shot from a tripod and you use
photoshop you simply can shift-drag the alpha channel to the other
images which is a matter of seconds.

If you meant something different with "remove tripod" please explain
more detailed.

--
Erik Krause
http://www.erik-krause.de

[Dave Evans]

I assume you are using an alpha channel to mask out the tripod.  If you do not use the exact same, pixel-for-pixel, alpha channel for all pictures you may see different, inaccurate colors, or even just gray.  In some instances you will be OK, in others you will not.  The algorithm PTGui uses for merging to HDR can take information from images which you might believe to be unused.  For each pixel there appears to be both a low and high threshold beyond which PTGui considers the data to be invalid.  If it is within PTGui's "good" range then the pixel in that image will affect the color.  Color information appears to be "averaged" from multiple images.

The above is based on experience trying to mask out movement within an HDR set.  I do not actually know the algorithm that PTGui uses for HDR conversion.

If you used a tripod to hold the image which you are masking out, it is very easy to just copy the alpha mask from one image to another.

Dave

[Ninoslav Adzibaba]

I've wrote a little PS script for copying Alpha channel to tiff's in
the bracketed sequences..
It's very handy when you have several HDR scenes and/or more than 3
bracketed exposures :)

Download is available at http://www.vrhabitat.com/#copyalpha1

All the best,
Ninoslav.


On Jun 24, 10:43 pm, Dave Evans <key-google-group-cont...@zeta-

tech.com> wrote:
> I assume you are using an alpha channel to mask out the tripod.  If you

> do not use the _exact_ same, pixel-for-pixel, alpha channel for all

[VenueView]

After much struggle with this issue, I have developed what I think is
a simple and effective solution.

1. First, make the nadir patch as small as possible. A review of our
technique:
http://www.venueview.com/panorama/pdf/easy_patch.pdf

2. For the nadir image, move the tripod, tilt over the nadir spot,
tilt the camera near level and, as steady as you can, shoot the same
bracket you used for the master images. Shoot three or four sets to
get choices of sharpness (you will only use one of these images).
Watch the shadows! You will be surprised how sharp your hand-held
image is when you are using only a tiny piece of the image of a very
wide lens.

3. Use Ingemar Bergmark's great EnfuseGUI to give yourself fewer
images to stitch. (Make sure to donate!)
http://software.bergmark.com/enfuseGUI/Main.html

4. Buy Pano2VR from Garden Gnome Software (free trial available).
This program is essential for efficient work-flow.
http://gardengnomesoftware.com/pano2vr_download.php

5. Watch the Pano2VR tutorial video on the Patch Tool. I gave up on
alpha channels a long time ago, just Photoshop the the patch you
export from Pano2VR using the de-fished nadir shot from step 2. Color
correction will be required.
http://gardengnomesoftware.com/tutorial.php?movid=09

6. I find Pano2VR the best way to export samples to the client
before programming in FPP. Example:
http://chelseadining.com/new/

Thats it! only 76 steps to a perfect pano. Used to be 134. Everyone in
this group knows how many moving parts there are in doing good
panoramas. My technique works really well for me. Getting the
mechanics out of the way is critical to produce good work efficiently.
We are very happy with the results.

Stephen Anderson
http://www.venueview.com

[Erik Krause]

Am 25.06.2010 17:01, schrieb VenueView:
> 2. For the nadir image, move the tripod, tilt over the nadir spot,
> tilt the camera near level and, as steady as you can, shoot the same
> bracket you used for the master images. Shoot three or four sets to
> get choices of sharpness (you will only use one of these images).
> Watch the shadows! You will be surprised how sharp your hand-held
> image is when you are using only a tiny piece of the image of a very
> wide lens.

The easiest is PTGui pro and viewpoint correction of course. Shoot the
floor from sideways using your tripod and let Blend Priority do the rest.

-> http://www.ptgui.com/examples/vptutorial.html

[VenueView]

> The easiest is PTGui pro and viewpoint correction of course. Shoot the
> floor from sideways using your tripod and let Blend Priority do the rest.
>
> ->http://www.ptgui.com/examples/vptutorial.html
>


> The easiest is PTGui pro and viewpoint correction of course. Shoot the
> floor from sideways using your tripod and let Blend Priority do the rest.

> ->http://www.ptgui.com/examples/vptutorial.html

Erik, thanks for reminding me.

So much of what happens in PTGui seems like magic that I have just
become set in my ways about the nadir shot. After two years of
struggle with the apex shot straight up into blank white ceilings
(apparently for no good reason), I have started to shoot two shots
rotated 120 or 180 deg tilted 60 deg up -- the results are excellent.

I will have to download the sample files to get this process
straight,
but it would be fantastic if I could get it to work the way it does
in
the tutorial.

It should be no problem using my Enfused image set for this techique
to work, is that correct?

This would be one big advance in my stitching and retouching
workflow.

Thanks again.

Stephen Anderson
http://venueview.com/