Since a long time i noticed that branched path tracing give brighter reflections than regular path-tracing, so i took the time to make a simple test with passes exposed and thi is what came out:
I see what i think is a big flaw in the diffuse indirect pass of the regular path tracing (last row right picture): it actually shows reflections! Is it maybe this additional pixel data the reason for the darker reflection passes?
I noticed something like this a while ago (the image looked darker in regular pathtracing and lighter in branched) but just I thought that I made a mistake in the rendering setup, don’t know if it was this issue or really just a mistake by myself.
Without the Blend file it’s really difficult to see if your settings are the same. Often increasing the number of bounces in the right environment can noticeably increase the brightness of a rendering.
I just tested the file again and it seems to be a problem with the clamping (direct) which makes the image darker with regular path tracing but doesn’t seem to have such a big effect on the lights when branched pathtracing is used. I don’t know if it’s supposed to behave like this but I think it’s not related to this issue.
Branched and pathtracing should give the same result, more or less. Assuming all the settings are a match, it looks like you found a bug. I’d report it to the tracker along with the blend file.
Ok i found the bug: reflections show up in diffuse passes if a glossy “sharp” node is in the shader mix
Can anyone give me directions to report the bug?
I already reported something like that and got told that differences are to be expected. Which sucks really, because especially clamping works totally different.
I remember the clamp thing being different IIRC, but not the glossy appearing in a diffuse pass…maybe mail the bf-cycles ML, drop a link to your tests, attachments don’t work.
EDIT: maybe lets correct the naming on the left which is quite confusing
Sure. Go here and fill out the form. Drag and drop the .blend into the big text box. You might need to set up an account there to do it though.
In the exact steps to reproduce write something like ‘open the attached blend and render. then switch to regular pathtracing and render again. note the difference between the two renders in the <insert pass here> pass.’ Make sure you set up your blend in such a way that it will actually show the difference if they do that. Also make sure it’s fairly minimal and uncontaminated by personal settings (reload factory settings before creating your example file).
Don’t be shy, the devs don’t bite. Worst case they’ll just tell you it’s not a bug and close it.
