Community
Arnold for 3ds Max
Rendering with Arnold in 3ds Max using the MaxtoA plug-in.
cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 

Mesh light shadow problem

14 REPLIES 14
Reply
Message 1 of 15
litote
2553 Views, 14 Replies

Mesh light shadow problem

I find that if I use an Arnold Mesh light, a Maya Directional light will cast shadows off the mesh item you used for the light. Is there any way to swiitch off the shadow?

14 REPLIES 14
Message 2 of 15
teddude75
in reply to: litote

Hey, you just need to turn off cast shadows. It's under the shape node, Arnold tab, visibility, and uncheck cast shadows.

Message 3 of 15
litote
in reply to: litote

@Edward Conry

I already tried that, it makes no difference (Maya 2017/Arnold 5). The only thing that worked was to turn off Casts shadows for the directional light. It does not work if you switch it off Casts shadows on the mesh itself.

Message 4 of 15
teddude75
in reply to: litote

Ok I got it to work. Use your mesh with an aiStandard surface and the emission weight and color(not mesh light). Than you can turn off cast shadows. You can also use aov or render layers to add the mesh lights in comp. But that might get a little bit messy.

Message 5 of 15
teddude75
in reply to: litote

Message 6 of 15
litote
in reply to: litote

@Edward Conry

Sorry, I don't follow what you mean.

- Use your mesh with an aiStandard surface and the emission weight and color (not mesh light)?

Message 7 of 15
teddude75
in reply to: litote

There's the mesh light under the Arnold menu, there's changing the shape from mesh to mesh light, and then there's turning on emission on the shader. If you use the shader than uncheck cast shadows on the shape node that would get you what you want.

@Greg Hughes

2142-meshlight.png

Message 8 of 15
litote
in reply to: teddude75

@Edward Conry

Thanks for your.. eh hem... illuminating answer.

I see what you mean now.

Message 9 of 15
joachimguerin
in reply to: teddude75

Hi! I have exactly the same issue. I understand the workaround with an emission shader but it's not really optimised. Do you have some news about it?

Thanks!

Message 10 of 15
Stephen.Blair
in reply to: litote

For the light sampling to work properly, a mesh light has to be visible to shadow rays (which means the mesh light will cast shadows).

If you make a mesh light invisible to all rays, you'll have no shadow but you'll see this warning in the Arnold log:

light_pTorus1Shape: for MIS to work properly, polymesh linked to mesh_light should at least be visible to shadow rays


// Stephen Blair
// Arnold Renderer Support
Message 11 of 15

Thanks for your answer Stephen!

But I don't see this log when I disable cast shadow from the attribute editor of the shape: shape / Arnold / visibility / Cast Shadows. (echo all command enabled)

Did you do it in another way?

Message 12 of 15

You need to know the name of the mesh that is exported to Arnold. It will be something like "light_pTorus1Shape@mesh"
Export an ass file to check the name.
Then use an operator to set visibility on that mesh.

But that warning means that light sampling won't necessarily work properly after you do that.



// Stephen Blair
// Arnold Renderer Support
Message 13 of 15
joachimguerin
in reply to: litote

Thanks! I got it now, it works on my side. Indeed, hope to don't have too much side effects!

Message 14 of 15
toyyoda95
in reply to: litote

Unchecking cast shadows does absolutely nothing for me. It's really annoying because I don't want a giant shadow beneath my soft diffuse light with no object in sight that might cast one.

Message 15 of 15
hanyilun2
in reply to: litote

Apply a materail with 0 opacity on the light mesh

Can't find what you're looking for? Ask the community or share your knowledge.

Post to forums  

Autodesk Design & Make Report