Hello! I've been experimenting with the number of photos to include in final HDRI.
I took a sequence of photos of a single LED with reflectance standards included in the scene. EOS7D 28-105mm lens at 28mm F16 1/8000-1/15’’ F4 1/30-5 mins With the ND filter t=0.0094 Images are fused with raw2hdr. They were calibrated at white reflectance standard 215 cd/m2. I’ve noticed the following tendency: If I fuse different number of photos (cut the number of photos on the shortest end), after calibrating at white reflectance standard, I get different luminance values for the LED. *Shortest exposure to fuse L,cd/m2* 1/125’’ f16 4.5*106 1/250’’ f16 9.06*106 1/500’’ f16 18*106 I've seen interesting discussion between Axel and Greg on photos to include. But it seems like there are many uncertainties. In HDRI second edition book it says "The darkest exposure should have no RGB values greater than 200 or so, and the lightest exposure should have no RGB values less than 20 or so. Do NOT include an excess of exposures beyond this range, as it will do nothing to help with the response recovery and may hurt." I assume it is the same for any HDRI sequence, not only for response curve. I have plenty of photos of dark exposures that have no values greater than 200, same with the light exposures and 20.If somebody can clarify what photos should be included or have any other suggestions that would be great Thank you, *Yulia *
_______________________________________________ HDRI mailing list [email protected] http://www.radiance-online.org/mailman/listinfo/hdri
