Arnold Procedural point cloud radius

[Anonymous]

I'm loading an alembic particle sequence from Realflow and setting the view type to Point Cloud but the radius of each particle is too big. Is there any way to adjust the size?

[Stephen.Blair]

Assuming these particles are rendered as an Arnold points node, you could use an operator to adjust the radius. But it would be one radius value for all particles.

[Anonymous]

Could you provide more detail? I‘m specifically trying to change the point radius in the viewport.

[Stephen.Blair]

So, not in the render? What I suggested is for Arnold renders.

For a render, you can add a set parameter operator, select the points node, and set the radius:
For example:
Selection = *.(@node=='points')
radius = 0.55

[Anonymous]

Right. Not in the renderer. Doing previs and just need to bake out the viewport with the particle cache but the Arnold Procedural draws points too large.

[peter.horvath6V6K3]

When displaying points in the viewport, the Arnold Procedural ignores the radius. It draws points with the default C4D API function, which does not accept any radius settings. So that radius you see comes from Cinema 4D and I don't think it can be changed.

[Anonymous]

Thank you for confirmation. When importing the same alembic file using the standard C4D loader it gives the option of Particle Geometry or Polygon Object which let you change the size in either Thinking Particle Settings or Viewport Display settings in the main prefs. Was hoping there was a parameter I overlooked. Have to use the Arnold Procedural loader as the native loader has some bugs when dealing with particle caches ( confirmed by maxon ).

[peter.horvath6V6K3]

Hmm, I'm not sure why the Viewport Display settings from the preferences do not affect the Arnold Procedural. I think they should, since I'm using the native API. I have to check with Maxon support.

[Anonymous]

I'm experimenting with using a .ass sequence instead of alembic and can't figure out how to set the radius using the operator method. Could you provide more detail?

[Stephen.Blair]

I don't know what is in the ass file, but assuming it is a points node, then:

Selection = *.(@node=='points')
radius = 0.55

[Anonymous]

Thanks Stephen for the fast reply. Unfortunately I have zero experience with Operators. Where would this even go?

[Anonymous]

Found this tutorial that covered how to do it in the gui. To get it working I had to drag the .ass contents into the field and set an assignment to floating point with the name "radius".

https://www.youtube.com/watch?v=5KgGiM_1a_8

Thank you for pointing me in the right direction.

[Anonymous]

Is there a way to randomize the radius using an expression between two values? Sorry for so many questions, but expressions really aren't my area.

[Stephen.Blair]

Unfortunately not, at least not with the random() function. Last time I tried, it didn't work, and I logged a bug for it (that bug is still open).

radius *= 10 / (random() + 0.2)^2

[Anonymous]

Glad to know I'm not going crazy. Nothing I tried worked. What's frustrating is loading the stitched alembic sequence gives a variation parameter that works perfectly. But I can't figure out how to get the Procedural to see more than one frame of the individual .abc file sequence.