[HDR-photo] Real-World example (Was: Alignment)

[Bernhard Vogl]

Hello Mark,

Some of the older panoramas were stitched with "pre-alignment". I had 
various problems with the older panoramas so i unfortunately can't tell 
anymore which panorama was purely created by this method.
All of these "pre-alignment" methods have one problem in common: When 
you stitch a panorama (doesn't matter which way) before HDR generation, 
you will never have pixel-exact alignment, because no real-world 
stitching (software) can align with the needed precision.
So it's also "just another workaround" and usability is depending on the 
purpose.  ;-)

The newer ones are batch-processed brackets with Photomatix - automatic 
alignment turned on - and - if needed also ghost removal. The sharpness 
mostly results from the higher useable resolution IMHO.

Back to the newer photos: I have prepared a set for Pablo and i hope he 
doesn't mind if i also post the link here.
I think it's the easiest way to talk about, if you can also have 
"hands-on". The published panorama on austria-360 was created by 
stitching the HDRs with Hugin in full HDR mode.

The caveats with this example (they are reduced in size, EXIF data 
included):
- sector HDRs->tonemapping->panorama doesn't work because of different 
DR of the sectors (looks like taken in auto-exposure)
- The HDR is technically not correct (too low DR) because the images 
were merged with a standard response curve. The images were captured 
with a Fuji S3 in extended range, but i can't use response curve 
calculation as this would mis-align the HDR brightness of the sectors 
(...the same problem as above).
-> This is a good opportunity to remind of the EXIF-discussion on this 
list some while ago: At least the Fuji records the real-world brightness 
value in the EXIF-data which would be a perfect starting point to 
normalize the HDR brightness.

The link is: ftp://87.106.53.4/public/pablo.zip
Login is "anonymous"

Best regards
Bernhard




>
> Hi Bernhard,
>
> Even more great panoramas from underground! (This will be invaluable 
> to the city as a record in later years...)  The more recent set is 
> much sharper, as you indicate. Are you doing any automatic alignment 
> or ghost removal during the HDR creation process, or do you attribute 
> this sharpness solely to stitching in 32 bits? In a following email 
> you mentioned "pre-aligning" with PTGui, but not in regards to these 
> shots. You obviously have my interest piqued regarding the quality of 
> these HDRIs, so please tell me more.
>
> -Mark