hi guys, Pls see attached quicktime. I am rendering a bunch of particles and I need to output some render elements (velocity and normals, specifically) and I seem to be getting glitchy passes on the normals and velocity.
The render on the left is the rgb, middle is velocity and right is normals. In the quicktime is a 25 frame sample but you can clearly see that the normals and velocity passes flicker like crazy, whereas the rgb pass does not. I am not doing any time manipulation on the prt and I rendered it without any KCM’s as well so that we could just see the straight results, as is. I am rendering with Krakatoa 2.6.1 on 3ds max 2016. I am rendering to exr’s, full float and non-filtered and no clamping.
Any suggestions on how I can debug this would be awesome. Thanks!
First thing to do in this case is to use Magma and visualize the data in the viewports. Does the data flicker there too? (Especially the Normals). If it does, then the Render Element is “right”, but the data is “wrong” (or at least unexpected). If that is the case, we need to look at where the data comes from - how was the Normals channels generated in the first place? Where do the particles come from? Do they have native Normals, or do you generate them somehow yourself?
If the data does not flicker outside of the renderer, then we need to look into why the Render Element outputs what it outputs…
I’ll let Bobo answer this one, but I can explain how the velocity and normal passes work in Krakatoa.
Because we can’t filter a vector the same way we filter colors, the pixels in a vector output pass will always take the value of the particle closest to the camera at that pixel. Vectors don’t blend like colors blend, so we don’t do interpolation on them using a filter. As a result, the image can look strangely flickery in a moving output sequence.
I’m not entirely sure if that is what is going on here. Perhaps Bobo has a better idea.