Fog with Path Tracing

Fri Jun 05, 2015 9:59 am

Is it possible to get some decent atmospheric mist/fog with path tracing in blender?

Fri Jun 05, 2015 6:16 pm

Yes, but it does take more time to get it noise free. All you need to do it to create a box or other object that encloses the fog, just make sure the camera is outside of it. Then set the material to specular and set the scatter to taste.

Sat Jun 06, 2015 1:52 am

Hm, ok, what am I doing wrong? I tried following the fog posts I found on here, seitched the kernel to direct lighting for a test. I only get a grayish, opaque material on my sphere (you can see faint edges of the quads of the sphere). Camera is outside, normals of the sphere point outward, material is displayed in the picture. Environment normal default sun with a sky texture.

Sat Jun 06, 2015 7:41 am

Here is a quick blend file for you to look at, I'm using Roubals method here.

fog-test.blend: (582.12 KiB) Downloaded 159 times

Make sure to recalculate the inside normals on the sphere around the camera, otherwise it will not work. Hope this helps.

Jason

Sat Jun 06, 2015 3:57 pm

Thanks a lot for the file! I found my problem .... scale. My spaceship is over a kilometer long and the camera pretty far away from it to get it onto the picture. I had to tune down the scatter value to an impossibly small number to get to a point, where it wasn't just all scatterlight..... I currently use 0.00002 .. I can't seem to go lower, or octane server errors. But: it's still way to bright then and I can't see the sky texture at all.

Is this scatter medium trick only usable for small scenes? I'd need an idea of how to add a little haze with real depth to scenes, that stretch for kilometers (huge landscape shots, entire planets etc).

Sat Jun 06, 2015 5:51 pm

I had the same problem, the picture above was rendered with Direct Light (ambient occlusion). PMC and PT appear to be broken and don't work very well. I was able to get PMC to work ok but there was no shadow attenuation so it didn't look very good.

I think we are going to have to wait for 3.0 to get a good fog.

Here is how it used to look with PMC on an older version of Octane (I can't remember which version). It doesn't look as good as this now.