MIS causes rays reflected off a glossy shader to be seen as something else #40243

New Issue

gandalf3 · 2014-05-18T01:43:04+02:00

gandalf3 commented

2014-05-18 01:43:04 +02:00

System Information
Archlinux
Nvidia GTX 460

Blender Version
Broken: f93b76

Short description of error
When using a light path node to mix between shaders based on the incoming ray type, MIS seems to cause issues. See http://blender.stackexchange.com/q/7915/599.

Exact steps for others to reproduce the error

Open Cycles_MIS_Light_paths.blend
Check rendered viewport, note that the node setup for the mesh light should be making it act as transparent, however it will render a glossy reflection of the mesh light (but not quite as bright a reflection as when the emission shader is connected straight to the output in the mesh light material)
Disable MIS on the mesh light. Now it renders as expected (the mesh light has no affect on the glossy portion of the floor shader)
Hide layer 2 and unhide layer 3 (keeping layer 1 visible) and look at the rendered viewport. Note that the point lamp has a similar setup to the mesh lamp, however MIS seems to have no effect on the lamp (It's always rendered "wrong", unless I'm just confused)

**System Information** Archlinux Nvidia GTX 460 **Blender Version** Broken: f93b76 **Short description of error** When using a light path node to mix between shaders based on the incoming ray type, MIS seems to cause issues. See http://blender.stackexchange.com/q/7915/599. **Exact steps for others to reproduce the error** 1. Open [Cycles_MIS_Light_paths.blend](https://archive.blender.org/developer/F89328/Cycles_MIS_Light_paths.blend) 2. Check rendered viewport, note that the node setup for the mesh light should be making it act as transparent, however it will render a glossy reflection of the mesh light (but not quite as bright a reflection as when the emission shader is connected straight to the output in the mesh light material) 3. Disable MIS on the mesh light. Now it renders as expected (the mesh light has no affect on the glossy portion of the floor shader) 4. Hide layer 2 and unhide layer 3 (keeping layer 1 visible) and look at the rendered viewport. Note that the point lamp has a similar setup to the mesh lamp, however MIS seems to have no effect on the lamp (It's always rendered "wrong", unless I'm just confused)

gandalf3 commented

2014-05-18 01:43:04 +02:00

Changed status to: 'Open'

gandalf3 commented

2014-05-18 01:43:04 +02:00

Added subscriber: @gandalf3

Brecht Van Lommel was assigned by Sergey Sharybin

2014-05-19 10:18:12 +02:00

Sergey Sharybin commented

2014-05-19 10:18:12 +02:00

Added subscribers: @brecht, @Sergey

Sergey Sharybin commented

2014-05-19 10:18:12 +02:00

@brecht, guess this one is for you :)

Brecht Van Lommel commented

2014-05-19 14:49:02 +02:00

Changed status from 'Open' to: 'Archived'

Brecht Van Lommel closed this issue

2014-05-19 14:49:02 +02:00

Brecht Van Lommel commented

2014-05-19 14:49:02 +02:00

This is a known limitation unfortunately, I haven't found a solution yet to solve this without introducing a major performance problem. Right now a direct lighting ray from multiple importance sampling is not considered a "glossy ray".

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MIS causes rays reflected off a glossy shader to be seen as something else #40243