disabling traceble (Blender Render) creates flickering #34171

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soenke maeter · 2013-02-08T19:24:47+01:00

soenke maeter commented

2013-02-08 19:24:47 +01:00

%%%tried it with different 2.6x windows 64-bit release versions, all showed the same bug

*open file
*press f12
*notice dots in shadow area
*activate traceable of sphere material
*press f12
*notice dots are gone

the occurrence depends on different factors such as: camera angle, aa settings, subdiv level, focal length
%%%

%%%tried it with different 2.6x windows 64-bit release versions, all showed the same bug *open file *press f12 *notice dots in shadow area *activate traceable of sphere material *press f12 *notice dots are gone the occurrence depends on different factors such as: camera angle, aa settings, subdiv level, focal length %%%

soenke maeter commented

2013-02-08 19:24:47 +01:00

Changed status to: 'Open'

Ton Roosendaal commented

2013-02-09 15:42:34 +01:00

%%%Hey Soenke, cool to see you here :)

The sphere has subsurf level 4, which means every face gets 64 small faces inside. These then are so tiny that the render code gets precision errors.
Using subsurf level 2 solves the problem. Also rendering it in 4k makes it almost go away.

I also noticed the error is independent of raytrace or shadow, also without any of this you get this. That means the tiny faces somehow get a bad normal - which is possible by rounding errors using 4 byte floats. Same happens in older blender versions.

These kind of errors are really tough to look into... typically (in modern 64 bits render systems) floats are being replaced with 8 byte doubles for that reason.

Because this area is not being worked on now, I copy this to our render todo, with this report linked for future reference (so we can test it when the topic is being worked on).
http://wiki.blender.org/index.php/Dev:2.5/Source/Development/Todo/Render#Render_Engine%%%

%%%Hey Soenke, cool to see you here :) The sphere has subsurf level 4, which means every face gets 64 small faces inside. These then are so tiny that the render code gets precision errors. Using subsurf level 2 solves the problem. Also rendering it in 4k makes it almost go away. I also noticed the error is independent of raytrace or shadow, also without any of this you get this. That means the tiny faces somehow get a bad normal - which is possible by rounding errors using 4 byte floats. Same happens in older blender versions. These kind of errors are really tough to look into... typically (in modern 64 bits render systems) floats are being replaced with 8 byte doubles for that reason. Because this area is not being worked on now, I copy this to our render todo, with this report linked for future reference (so we can test it when the topic is being worked on). http://wiki.blender.org/index.php/Dev:2.5/Source/Development/Todo/Render#Render_Engine%%%

Ton Roosendaal commented

2013-02-09 15:42:34 +01:00

Changed status from 'Open' to: 'Archived'

Ton Roosendaal closed this issue

2013-02-09 15:42:34 +01:00

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Reference: blender/blender#34171

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disabling traceble (Blender Render) creates flickering #34171