Indeed. If by non-saturated you refer to every single channel. With the sun, for example, it happens quite often that the Luminance histogram indicates you're good, but when you look at the red channel that still clips.
However, there are other problems with environments that have primarily small concentrated light sources. - Most alignments fail for the most under-exposed images. Well, you shoot your pano on a tripod anyway. - You need to be very careful editing the HDRs, even a resize with the wrong filter can cause color fringes. Stick to Bilinear to be safe. - IBL needs sampling settings beyond insane. Ultimately, these concentrated light sources are perfect examples of direct illumination sources. Brute-forcing this through a GI render pipeline makes little sense. It's much more efficient to represent these concentrated light sources with actual 3d lights, and in turn limiting the DR in the environment map. Also gives you more artistic control over shadows. Some people like to paint out direct light sources completely, but I prefer blurring them out with the rest of the environment to keep some ambient contribution (think hazy spill light). Hope this helps, Blochi On Jan 25, 2011, at 8:20 AM, jason huang wrote: > Hi, Greetings to all in the mail list, > > I have couple questions in the context of capturing HDR environment > map for image-based lighting, and would like to hear your feedbacks. > > When capturing the HDR environment map for a scene with concentrated > light sources (say light bulb or the sun), is it correct that if the > pixel values of the light source are not saturated in the most > under-exposed bracket (but saturated throughout the rest of exposure > brackets), the full dynamic range of the light source is well > preserved? > > If I have two, three, or more under-exposed brackets presenting > non-saturated pixels for the same concentrated light source, will the > resulting HDRI be more accurate in terms of representing the > illumination of the light source during IBL than the situation where > the non-saturated pixels of the light source only present in the most > under-exposed bracket? > > Thanks, > Jason > > _______________________________________________ > HDRI mailing list > [email protected] > http://www.radiance-online.org/mailman/listinfo/hdri _______________________________________________ HDRI mailing list [email protected] http://www.radiance-online.org/mailman/listinfo/hdri
