Comments on: Motion Vector Driven Occlusion http://www.xsi-blog.com/archives/119 People and thoughts behind XSI in production... Thu, 16 Oct 2008 02:02:40 +0000 http://wordpress.org/?v=2.6 By: George R http://www.xsi-blog.com/archives/119#comment-14375 George R Wed, 21 Feb 2007 12:25:34 +0000 http://www.xsi-blog.com/?p=119#comment-14375 Where do I get mib_amb_occlusion? Google isn't helping me out. Where do I get mib_amb_occlusion? Google isn’t helping me out.

]]> By: Guillaume Laforge http://www.xsi-blog.com/archives/119#comment-7880 Guillaume Laforge Sun, 19 Nov 2006 13:15:29 +0000 http://www.xsi-blog.com/?p=119#comment-7880 Hi, Here is an updated "Motion Vector Driven Occlusion" preset : http://www.vol2nuit.fr/guillaume//articles/AO_MV/2dMVDO.Preset And the updated part of the render tree : http://www.vol2nuit.fr/guillaume//articles/AO_MV/2DvectorLength.gif The motion vector origin is now the camera. It is projected on the camera plane to evalute the length in 2d space. This way, the new preset will return correct vector length if the object move very fast on the z camera axis for example. Cheers Guillaume Laforge Hi,

Here is an updated “Motion Vector Driven Occlusion” preset :
http://www.vol2nuit.fr/guillaume//articles/AO_MV/2dMVDO.Preset

And the updated part of the render tree :
http://www.vol2nuit.fr/guillaume//articles/AO_MV/2DvectorLength.gif

The motion vector origin is now the camera. It is projected on the camera plane to evalute the length in 2d space.
This way, the new preset will return correct vector length if the object move very fast on the z camera axis for example.

Cheers

Guillaume Laforge

]]> By: Stefano Jannuzzo http://www.xsi-blog.com/archives/119#comment-7649 Stefano Jannuzzo Tue, 14 Nov 2006 16:55:05 +0000 http://www.xsi-blog.com/?p=119#comment-7649 I also agree on the factory-nodes-only rule. I also agree on the factory-nodes-only rule.

]]> By: Guillaume Laforge http://www.xsi-blog.com/archives/119#comment-7648 Guillaume Laforge Tue, 14 Nov 2006 16:46:23 +0000 http://www.xsi-blog.com/?p=119#comment-7648 Thanks Stefano. My first test was made with the lm2DMV shader (and also the mib_amb_occlusion). I rebuild it from scratch for the "public preset" with only built in shader to be sure any readers could try it without installing other shaders. But you are right, it needs to be "rasterised". I will try to send an update with projected vectors on the camera plane as soon as I find the time ! It looks like a good render tree exercice :-). Thanks Stefano.

My first test was made with the lm2DMV shader (and also the mib_amb_occlusion). I rebuild it from scratch for the “public preset” with only built in shader to be sure any readers could try it without installing other shaders. But you are right, it needs to be “rasterised”. I will try to send an update with projected vectors on the camera plane as soon as I find the time ! It looks like a good render tree exercice :-).

]]> By: Stefano Jannuzzo http://www.xsi-blog.com/archives/119#comment-7647 Stefano Jannuzzo Tue, 14 Nov 2006 16:29:00 +0000 http://www.xsi-blog.com/?p=119#comment-7647 Brilliant! May I just object that the threshold test should be performed someway in raster space, as for instance a huge xyz motion may result in a tiny raster motion. Too bad the standard vector transformation node does not include a "To Raster" option. Probably you could use the lm shader. Or, subtract from the motion vector its projected component along the ray (view) direction, before testing its length. Brilliant!
May I just object that the threshold test should be performed someway in raster space, as for instance a huge xyz motion may result in a tiny raster motion. Too bad the standard vector transformation node does not include a “To Raster” option. Probably you could use the lm shader. Or, subtract from the motion vector its projected component along the ray (view) direction, before testing its length.

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