Hi Lars, > For capturing a LED, there is no need for a fisheye though, so here one > or more filters might be an option. Of course one would have a very > close look at how "neutral" that density filter actually is.
True enough. I need a 180deg lens for the glare, though. The veiling glare might be less of a problem with non-fisheye lenses. Note that McCann and Rizzi use an 'ordinary' lens, not a fisheye. >> Either way--you'd want to expose (much) longer than a full cycle which >> is only 1/100 sec. This severely limits the range of exposure times >> available for the HDR sequence. If I remember correctly, Santiago >> Torres captured sunny skies in his PhD thesis, and he had to use two >> identical cameras for this, one of which was fitted with an ND filter. >> Aligning the two must have been a nightmare. > > Actually there are codes around doing the alignment by the use of shared > keypoints. I mentioned Hugin before - I have not used it to get > photometric values from images, but it claims to handle HDR formats, > includes a lot of alignment functionality, and is free. Maybe worth to > try it? Another question is how close two "identical" cameras can get... I'm trying to use Hugin for vignetting calibration. The results so far are not very consistent between themselves (different apertures), and with what little is published on vignetting of the Sigma 4.5mm. I have to say that I have not explored all options yet. Using two or more cameras is not an option in my case--I only got one. Axel _______________________________________________ HDRI mailing list [email protected] http://www.radiance-online.org/mailman/listinfo/hdri
