Christian Griese

I have a project involving a Aurora Borealis.
I already build a rather complex Asset creating a extruded curve with proper colours and animation.

Now I want to create a volume with colour and no density. This is to not occlude parts of the aurora and assimilate brightness with depth.

I tried to use the emission attribute in the volume visualisation node to get some emission but it doesn´t do anything, even if i use the density field with a ramp.

What works is using a billowy smoke Shader and piping the Cd into “emit Clr” on the volume model. Now my main problem is, how to import costum fields inside the shader instead of Cd Attribute.

2nd Problem: What´s the best way to create a volume from my geometry and transfer the Colour. I need very fine details. Volume from point fades out pretty far. The Colour of the aurora is vertice based. No texture maps whatsoever.

I have a scene with many hundred small fbx readouts as Geo nodes from one single fbx file.


When I render even with constant shader passes, 80 % of the render time goes into writing out the geometry for every single frame, although there is only camera animation, the rest of the scene is static.

I´m searching for a way to tell mantra to only write out the geometry on the first frame.

Tried to cache the geo with a mantra archive but since that only handles individual geometry nodes that won´t work eighter.

Does anyone have a solution? I render with the raytracer, no micropolygons involved.

Can´t post the scene unfortunately since it´s CAD Data from a engineering visualisation.

You could convert your geometry into a Volume, create an offset to the volume, and use that Volume as a mask for any kind of field like gravity. That should do the trick with particles, FLIP Fluids and Fluids.