hugin-devs team mailing list archive

[tmodes <1396940@xxxxxxxxxxxxxxxxxx>]

Hi Terry,

nothing odd here. The issue is that the pano was shoot in aperture priority mode and so the base exposure of each stack slightly changes: the first 2 stacks and the last stack have a base exposure time of 1/200 s, the 3th and 4th stack have a base exposure time of 1/250 s. This translates to exposure values of 12.6 and 13. And the stack detection code use currently a fuzzy value of 0.3 as maximum difference in the base exposure.
So if the use only the first two stacks the stacks are detected, with the third stack not. It has nothing to do with downscaled or not.
Increasing the fuzzy distance from 0.3 to 0.5 fixes the issue for your example (file src/hugin_base/panodata/Panorama.cpp, line 2072). 
But I don't know if this has other side effects, e. g. for not detecting stacks with a lower bracketed sequence (with +-0.66 EV)?
Or can we assume that only bracket sequence with >=1 EV are used? Then a difference of 0.5 would be fine.
Comments?

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https://bugs.launchpad.net/bugs/1396940

Title:
  Stack detection - odd behaviour

Status in Hugin - Panorama Tools GUI:
  New

Bug description:
  I'm working with hugin_executor branch (6769:aed7abb78308) built on Fedora 20 x86_64.
  I have a set of bracketed shots (0,-1EV, +1EV),
  When loaded into hugin, hugin detects that there is varying exposure but can't find any stacks.
  If a subset of these images are downscaled (from 4828x3264 to 2000x1325) and loaded into hugin stacks are automatically detected correctly.
  A check of the exif data using exiftool and exiv2 suggests that there has been no change to the exif data, or none that I have noticed.
  Is this a bug, or simply a result of hugin having a different number of images to decide on whether there are stacks?
  I have extracted the thumbs and with the exif data for the original images as well as the downsized images and these are attached.

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