Comments for all noise http://www.bzztbomb.com/noise code and randomness Mon, 08 Jun 2009 08:51:49 -0700 http://wordpress.org/?v=2.8.6 hourly 1 Comment on Probabalistic Shadow Map Technique Comparisions by realtimecollisiondetection.net - the blog » Catching up (part 2) http://www.bzztbomb.com/noise/?p=32&cpage=1#comment-305 realtimecollisiondetection.net - the blog » Catching up (part 2) Mon, 08 Jun 2009 08:51:49 +0000 http://www.bzztbomb.com/noise/?p=32#comment-305 [...] variants of VSM. Brian Richardson offers up some screen shots of different shadow methods in Quick Probabilistic Shadow Map Comparisons. Finally, there are so ridiculuously many shadow presentations coming out of NVidia alone, that [...] [...] variants of VSM. Brian Richardson offers up some screen shots of different shadow methods in Quick Probabilistic Shadow Map Comparisons. Finally, there are so ridiculuously many shadow presentations coming out of NVidia alone, that [...]

]]> Comment on Why are these new shadow map techniques filterable!? by bzzt http://www.bzztbomb.com/noise/?p=28&cpage=1#comment-304 bzzt Fri, 12 Sep 2008 17:02:20 +0000 http://www.bzztbomb.com/noise/?p=28#comment-304 hahaha, nah, I just need to slow down and work through the math. The last time I read through it, I was mostly concentrating on the log filtering. Which is quite clear! It was a good call to list all of the transformations you made to go from w0e^x + w1e^y (on page 270) to the final filtering equation. It made it pretty clear how it works. I just need to follow the rest of the math in the theory section as closely as I did the log filtering to get the rest of it. ;) hahaha, nah, I just need to slow down and work through the math. The last time I read through it, I was mostly concentrating on the log filtering. Which is quite clear! It was a good call to list all of the transformations you made to go from w0e^x + w1e^y (on page 270) to the final filtering equation. It made it pretty clear how it works.

I just need to follow the rest of the math in the theory section as closely as I did the log
filtering to get the rest of it. ;)

]]> Comment on Why are these new shadow map techniques filterable!? by Marco Salvi http://www.bzztbomb.com/noise/?p=28&cpage=1#comment-303 Marco Salvi Fri, 12 Sep 2008 16:46:07 +0000 http://www.bzztbomb.com/noise/?p=28#comment-303 This means I have to improve my articles-writing-skills :) This means I have to improve my articles-writing-skills :)

]]> Comment on Why are these new shadow map techniques filterable!? by bzzt http://www.bzztbomb.com/noise/?p=28&cpage=1#comment-302 bzzt Fri, 12 Sep 2008 07:08:25 +0000 http://www.bzztbomb.com/noise/?p=28#comment-302 Woah! Thanks for commenting! I've got ShaderX6 and I'll probably have re-read your article a few more times before everything clicks for me. ;) Woah! Thanks for commenting! I’ve got ShaderX6 and I’ll probably have re-read your article a few more times before everything clicks for me. ;)

]]> Comment on Why are these new shadow map techniques filterable!? by Marco Salvi http://www.bzztbomb.com/noise/?p=28&cpage=1#comment-301 Marco Salvi Fri, 12 Sep 2008 05:47:20 +0000 http://www.bzztbomb.com/noise/?p=28#comment-301 Brian, You should buy ShaderX6 and read my article about ESM, you can find in it also your own interpretation of it :) Even though it's not true that whatever smooth-monotonic function will do. Note that in the ESM case there are 2 ways of approximating a step function, the one that you showed and another one that goes from -inf to 1. While the first one suffers from light bleeding on non planar receivers the second one suffers from over darkening. That's the price one has to pay with approximations ;) Even though it's easy to replace the step function/occlusion test with another function that looks 'good', you are going to have all sort of different problems when geometry or lights move. Moreover a generic function doesn't allow you to know (in the general case) what rules you should apply while filtering your shadows. Blurring your map(s) like you can do with ESM or VSM is not magic, only works for specific reasons. For example I used exponentials because those are the only functions that can make light bleeding invariant under translations. It doesn't sound like a big deal but you don't really want your shadow to get significantly darker or lighter just because your objects are moving around some light ;) VSMs replaces step functions with a 2D -> 1D mapping, perhaps you can experiment with some 3D textures as well :) Brian,

You should buy ShaderX6 and read my article about ESM, you can find in it also your own interpretation of it :)
Even though it’s not true that whatever smooth-monotonic function will do. Note that in the ESM case there are 2 ways of approximating a step function, the one that you showed and another one that goes from -inf to 1. While the first one suffers from light bleeding on non planar receivers the second one suffers from over darkening. That’s the price one has to pay with approximations ;)

Even though it’s easy to replace the step function/occlusion test with another function that looks ‘good’, you are going to have all sort of different problems when geometry or lights move. Moreover a generic function doesn’t allow you to know (in the general case) what rules you should apply while filtering your shadows.

Blurring your map(s) like you can do with ESM or VSM is not magic, only works for specific reasons. For example I used exponentials because those are the only functions that can make light bleeding invariant under translations. It doesn’t sound like a big deal but you don’t really want your shadow to get significantly darker or lighter just because your objects are moving around some light ;)

VSMs replaces step functions with a 2D -> 1D mapping, perhaps you can experiment with some 3D textures as well :)

]]> Comment on Why are these new shadow map techniques filterable!? by bzzt http://www.bzztbomb.com/noise/?p=28&cpage=1#comment-300 bzzt Wed, 10 Sep 2008 22:30:03 +0000 http://www.bzztbomb.com/noise/?p=28#comment-300 hah, this is explained in this slidedeck: http://developer.download.nvidia.com/presentations/2008/GDC/GDC08_SoftShadowMapping.pdf hah, this is explained in this slidedeck:

http://developer.download.nvidia.com/presentations/2008/GDC/GDC08_SoftShadowMapping.pdf

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