HtoA can't remove shadow from mesh light

[ehumbert77E34]

I find that if I use an Arnold Mesh light, other lights will cast shadows off the mesh used for the light. Is there any way to switch off the shadow?

I already tried to disable the cast shadows tickbox of the mesh light, it's not working.

My geometry has an emissive shader, shadows disabled, opaque disabled and is not visible to diffuse/spec.

If I turn off the meshlight the geo is not casting shadows but as soon as I turn on the mesh light it will cast shadows again.

[Stephen.Blair]

This is not HtoA.

An Arnold light has to be visible to shadow rays. That's why a visible mesh light casts shadows.

[am_wilkins]

Hey everyone,

We've run into the same issue here, which appears to be some limitation of Arnold according to Stephens reply there?

Just wondering what the solution is—since there are few circumstances you would actually want a mesh light to also cast shadows from other light sources (like the sun)

We've noticed if we use Houdini "Light Linker" shadow linking, this appears to work in disabling the shadow cast by the mesh light but we really don't want to use shadow-linking as its hacky and very non-visible in the HtoA implementation.
(stored on a hidden parameter on lights)

Any further ideas?
Andrew

[mail]

Digging out this ol' thread as I'm running into the same problem. However Stephen says "An Arnold light has to be visible to shadow rays." but that doesn't seem to be true for Arnold non-mesh lights as seen by the arnold cylinder light here. I tested the same with an arnold quad light and also that didn't cast any shadows from the spot light up top. So why does a mesh light have to cast shadows - seems like a double standard.

[mail]

to @am_wilkins : Our workaround is to assign a fully non-opaque (opacity set to 0/0/0 - don't confuse with transmission) to the geometry it vanishes from view. However I would think this comes at a cost of ray-depth so it might still not look the same as a non-mesh light in reflections/refractions etc. I need to dig more into this.