Great discussion on HDRI in the forum. Chris Tyler posted come good info, as well:http://www.stratacafe.com/forum/topic.asp?TOPIC_ID=3317
Since Strata can't take HDRI images (.hdr format), the question was risen as to how to get as close to HDRI as possible in Strata.
In my past GlowDome overview, I talked about what HDRI is and how I go about trying to achieve a reasonable facsimile of it by using on eimage in the Diffuse, Diffuse map, Ambient, and Glow channels of the glow texture that I wrap around the Glowdome.
Chris posted in the thread above that he puts the same bitmap into the Stencil channel also where it is instantly converted to a greyscale image. Sometimes, he will enhance the contrast of that stencil image in PS (his image editor), as well.
This was, needless to say, very appealing for me to try, because, it answered the basis of HDRI's success.. the ability to layer images of varying color ranges into one image for alight source...
By laying the grayscale of the image in the Stencil channel, Chris has accomplished making each texture map with it in a "lighting range". Stack enough of them, and, indeed, you have a true twin sister to HDRI.
So, above, are 5 images I did in haste this am... (all rendered Radiosity HQ Good, with a few light tweaks to the cache, reflection recursions, and Octree Height to suit my personal taste and availability of time to render):
1. Standard Glowdome.. nice.. if I had used Stochastics on it to hide the shadow artifacts, it would have been quite acceptible, but notice, not a really large lighting range with broad spectrum of colors.
2. Standard Glowdome, BUT, I put the image into the Stencil channel of the Glow texture, and increased the Glow factor to 3.5. (Note next to image #2 above with glow factor of 1.5 is incorrect). Very nice. Especially with stochastics on.
3. 2 GlowDomes (something Ihave been experimenting with of late). Outer glowdome is glow texture without the image in the Stencil channel. Inner glowdome is sized 1" smaller, and the image is also in the Stencil Channel, AND, to make sure that the outer glow lights the scene as well, the OPACITY channel is set to "0" (no map, just the slider). Very nice, but, the neccessity of the transparency loses a bit of the dynamic nature of the lighting scheme. But, the color range does improve vastly.
4. One glowdome.. stacking two textures, the botom one with no image in the Stencil channel, the top one with it, and the Glow in the top texture is set to 3.5. Top texture is mixed as "replace". Really nice.. a bit dark, though, but the color range has become extraordinary.
5. One Glowdome, stacking two Glow textures, the bottom one without the image in the Stencil channel, the top one with it, and a glow factor of "1", but this time, "Mix" = "Combine. This is likely the very best of the bunch.. the color range is very wide, with good dispresement and contrast... all around best.
Chris has indicated that he is currently putting together a turorial on this... for all who really want to master this, it would be wise to jump all over it when he is done.