Hugin 'Stacks'

[Jules]

Hi List,

I'm trying to use hugin to produce HDR images for use in computer
graphics. I've got a load of bracketed exposures, and I'm trying to
generate a full HDR panoramic out of it.

I've been following the tutorial here:

http://hugin.sourceforge.net/tutorials/enfuse-360/en.shtml

But it is very brief when it describes:

'The alignment technique I used is to align each set of three
bracketed photos as a stack, then picking just one picture from each
of the four stacks and aligning these together just like a normal
panorama.'

How do you create such stacks? How do you klet hugin know that I have
seven 'stacks' of seven images and these stacks should use the same
control points?

Many thanks for any help.

Jules

[Eduardo Perez Esteban]

I do HDR panoramas, too; but my workflow is completely different:

At the field, I always use a tripod, so the different exposures from each camera position all match perfectly. Later when dealing with the files, I create one panorama for each exposure, and then merge them into a HDR; these are the steps I follow:

First, I copy all the files from the first exposure to file1, file2, file3... . Then I create a LDR panorama with Hugin, and call it pano1. Without closing Hugin, I copy all the files from the second exposure over file1, file2, file3..., execute the same panorama and save it as pano2.

With this technique, I obtain a stack of panoramas pano1, pano2, pano3, ... perfectly aligned, that I can handle with enfuse / pfstools normaly. There is a longer description here: http://edu-perez.blogspot.com/2008/12/panoramica-nocturna-de-barcelona-en-hdr.html, but I am afraid it is written in Spanish.

Hope this helps,
Edu.

[cri]

I've used with success the technique described on the tutorial. Let's
say you take 3 exposures (well exposed, under exposed, over exposed)
of each scene and you capture in total 2 scenes ("a" and "b") to merge
in an HDR panarama; you need to set control points in this way:
- between the 3 different exposures of "a" scene;
- between the 3 different exposures of "b" scene;
- between 1 shot of "a" scene and 1 shot of "b" scene (I prefer to use
the well exposed shots for this step because generally you could spot
more control points)

I hope I've make it clear!

[Yuval Levy]

there are many different ways that lead to Rome... or to Barcelona in
your case, Eduardo.

stitching and stacking or stacking and stitching are the two families.
<http://panospace.wordpress.com/2008/10/08/exposures-stacks/>

since most tools can't handle yet the 360° seam nor zenith/nadir for
full sphericals I use stacking first. It has also the bonus of being
faster. For true HDR it does not really matter because the stitched
result must be tonemapped and the tonemapping tools don't handle the
seams...

Yuv