Vertex map and field in C4d not working with Hair in Arnold

[jonathan.shine]

HAIR_VERTEX_FIELD.c4d.zipI'm using a box field to generate a vertex map that defines where hair is generated on an object in C4D. In Arnold Render, the vertex map isn't effecting the hair in the same way as in native C4d render. I have tried ticking "Render via Hair Render effect" on the Arnold Tag (applied to the hair object) - but still not working. Is there a work around for this? I've (now) attached scene file to show current setup.

[jonathan.shine]

Just to clarify - the vertex map is controlling the "length" parameter within the C4D hair material. The vertex map itself is defined by a box field.

Seems like Arnold cannot "see" the vertex map's effect on the C4D hair parameter.

Any help greatly appreciated! It's the only part of a wider scene that I can't get right with Arnold.

[peter.horvath6V6K3 · Accepted solution]

Just had a similar issue recently. Did you try to render it in the IPR or to the Picture Viewer. There's a good chance that it won't show up in the IPR, but the final render is fine. You need the 'Render via Hair Render effect' option enabled.

[peter.horvath6V6K3]

Just checked your scene and renders fine to the Picture Viewer. Just make sure the Hair Render effect in the render settings is enabled.

[jonathan.shine]

Amazing! Thank you so much for your help Peter. I was rendering to the IPR - re-enabled the "Render via Hair Render Effect" - and it's now working as it should! Thank you so much for your quick response!

[jonathan.shine]

Thank you Peter - your combined advice has sorted the issue out! Working great now 🙂

[ssjenforcer191191191]

How did you get it to work?

I tried everything you mentioned above.  ipr and render dont have vertex map variation.

EDIT:
nevermind.  I got it working.

Still no way to get it to work in IPR?  Would help.

[peter_horvath]

> Still no way to get it to work in IPR?

Unfortunately not. The hair is generated by the Cinema 4D hair system, that's why it needs the "Render via Hair Render Effect" option turned off. The simulation, since it can be expensive, is only available in the render context, not in the active scene context, that is the IPR. It's not an Arnold limitation, Arnold just takes the data (curves) from Cinema 4D.