OTOY Forums

I am trying to recreate condensation on a can the same way as Raphael Rau has done here:

https://www.behance.net/gallery/3712205 ... hael%2Brau

But I'm running into problems.

1. I have scattered some spheres on a poly surface which look fine until I put the surface in a SDS, the spheres then get shifted off the surface - can I fix this? Or is scatter not good with SDS? Should I make the surface editable first?

2. Can I restrict the scattering using a polygon tag? If I can't do that and have to use a vertex map, can I convert a polygon selection to a vertex map?

3. I have the distribution ion the scatter object set to surface, but the spheres seem to gather in certain areas where the mesh is densest, can I adjust where they tend to collect? Raphael's look much more even than mine.

1) It's not the spheres that are shifting, it's the rendered SDS. The SDS has different contours than the source mesh, and often is, "smaller" or "lower. If the Scatter is using the source mesh to calculate position, then the two won't agree. To make your scatter objects use the SDS surface you have to actually add the SDS surface in the Octane Scatter/Distribution/Surface slot, instead of the low res source mesh.

2) As far as I can tell, you can't use the poly tag to restrict placement, but yes, you can convert that selection and use it as a vertex map, or you can use your own shader generated however you choose, (but not Octane's own noise shaders - if you need procedural noise, use C4D's - GPU vs CPU generated noise - the Baking Texture node doesn't seem to work in this situation). You can even use both in conjunction. You can then use the min/max setting to control the range of values of that map are populated. It's not weighted, though; it's binary, all or nothing, no variation in population density. So for instance from 25% min to 75% max of the map value will be populated, but all at the same density. That's not true when using shaders in Position, Scale, and Rotation. There, you can actually use the gradient to drive the attributes across a range of values.

3) Yes, Scatter does use the surface areas of the polygons for calculating distribution. You can at least partially counter-act this with the "keep away" function, at a bit of a performance cost. "Keep Away" works better with simpler geometry on your scatter objects; a cube will calculate "keep away" far faster and better than a complex tree, for instance.

I think this is true for both Octane 4.x and 2018, but we haven't made the jump to 2018 yet. As far as I know, there haven't been changes to how the Scatter object works.