dayvbrown Posted January 16, 2014 Share Posted January 16, 2014 Hi all, Having some more issues with the new raytraced sss model. This is going to be one of those annoying posts where I can't upload a file so let me try and describe the issue.... So the file is setup as follows - smelly maya animator -> alembic export\import of character -> timeblend to create subframes -> surface model shader with SSS model set to "raytrace" -> pbr mantra with geo time samples > 1 and allow motion blur checked on and frame centred moblur. Now the issue we're getting is when rendering with motion blur (plain mantra deformation or trail calculated "v" based geo blur) large swathes of the sss pass are coming out very very dark, almost like there's a shadow moving across the character. Without moblur all is well and terribly sexy. Now interestingly increasing the raytracing bias mitigates the issue to some degree... which might be a workaround except that it creates a whole bunch of other non related issues in the process (with other objects etc...). Using a mix of local brdf and global point cache also seems to be stable across frames, but the end result is different enough to not be acceptable at this stage in the process. I know it's hard to comment without seeing a file but can anyone think of settings or areas to investigate? I've done quite a bit of troubleshooting already but i'll leave it open for any and all suggestions... Thanks again, Dave. Quote Link to comment Share on other sites More sharing options...
dayvbrown Posted January 16, 2014 Author Share Posted January 16, 2014 Should also specify that doing tests on "internal" houdini animation (various geo deformations based on keys and\or expressions) gives no such issues, my thought is that there is something within the created subframes that is causing the issue... mantra isn't raytracing those subframes for the sss maybe... not sure. Subframes are definitely being created and the motion blur itself is perfectly fine but as I say... sss issues. Quote Link to comment Share on other sites More sharing options...
Guest tar Posted January 16, 2014 Share Posted January 16, 2014 looks like a bug - I've attached this test scene if you want to submit it to SideFx TheSSSFiles.zip Quote Link to comment Share on other sites More sharing options...
dayvbrown Posted January 16, 2014 Author Share Posted January 16, 2014 Great thanks for following that up for me Marty, at least good to see the behaviour replicated. Will submit to sidefx and see how we go! Thanks again, Dave. Quote Link to comment Share on other sites More sharing options...
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