Re: Importance sampling and sharp shadows in IBL

[Dawa <dawa(at)topixfx.com>]

Basically we are just trying to find the best solution to recreating information captured on set accurately in our renders. We are just looking at options. We noticed that we have to create hard shadows manually, when using mental ray IBL. It would be nice to have it automated somehow. A test in Vray had great results very fast, and we are wondering how and why we can't reproduce it. Also we've had decent results in Houdini using occlusion (although im not very clear on how it all works in Mantra). Thse maya plugins look good, we will test them out in maya and maybe it will be worth while porting them.

Dawa

Andy Jones wrote:

What ever happened to BA_Lightdome?  That's the specific tool I know of to generate these sorts of light rigs.  Also relevant is this article: http://gl.ict.usc.edu/research/MedianCut/.  I'm not sure to what extent Holger's lightdome implements that algorithm.  I wouldn't be surprised if it does something better, as the Median Cut system doesn't really describe how to deal with the "sharpness" of the light source.  Whereas Holger's thing makes use of area lights, which presumably means he tought about this.

The down-side of the light-driven approach is that it doesn't do the same optimizations FG does for smoothing the light across the screen space.  The up-side is that since it doesn't do that, it will be able to deal with finer details in the image, the same way AO sort of works better at catching small bevels and stuff than FG/GI.

- Andy

André Adam wrote:

Would the Create Light Rig From Image tool be an option for your scenario? I don't think it would get you the whole way, but it could make a reasonable starting point.

   -André


Chris Johnson wrote:

> I don't see the point of using an HDR image to create sharp shadows. Ray tracing lights are made just for that.

Your using the HDR Map to tell where the shadows should be coming from in a real world scenario using the intensity of the image to calculate the intensity of the shadow as opposed to having to use a light and guesstimating where it should be.

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Dawa Fruitman
Animation director

TOPIX
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