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Arnold AOV opacity/transparency

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Message 1 of 9
dmzscripts
1120 Views, 8 Replies

Arnold AOV opacity/transparency

Hi. I am trying to render helicopter blades with a greyscale image texture. 

 

What I am noticing in several OAV passes (AO , object id, Standard Surface Shader aovs), is that the transparency of the texture is not rendered correctly. It seems as if the greyscale values are lost and the AOVs collapses the values to 1 or 0.

 

renders with blades:

dmzscripts_2-1682009886918.pngdmzscripts_3-1682009895354.pngdmzscripts_4-1682009907984.png

 

renders without blades:

dmzscripts_8-1682010032546.pngdmzscripts_6-1682010002934.pngdmzscripts_7-1682010014551.png

 

I've tried several techniques and looked online for tutorials or any information, however documentation is very limited on this matter. Does anyone have and idea on how to render half-transparent textures  as an AOV pass?

 

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8 REPLIES 8
Message 2 of 9
Stephen.Blair
in reply to: dmzscripts

That isn't motion blur? (for spinning helicopter blades?)



// Stephen Blair
// Arnold Renderer Support
Message 3 of 9
dmzscripts
in reply to: Stephen.Blair

Its a texture. I tried rendering it with Standard Surface in the opacity and transmission slots and Matte opacity. Both render the texure fine in the regular render pass (as seen in the screenshots), but the AOV's for Ambient Occlusion, ObjID, Standard Surface AOV ID's all render the opacity  wrong.

HelicopterBlade_Blur01_rgb.jpg

Message 4 of 9
dmzscripts
in reply to: dmzscripts

Is there anyone at Autodesk that could clarify if rendering half transparent textures is possible in Arnolds AOV passes, like ao or obj/material ids? 

Message 5 of 9
Stephen.Blair
in reply to: dmzscripts

Transmit AOVs will work with textures, but only for light-path AOVs like diffuse. ID AOVs seem to ignore the texture.

 

transmit_aovs_id_aov.jpg



// Stephen Blair
// Arnold Renderer Support
Message 6 of 9
dmzscripts
in reply to: Stephen.Blair

Thank you for the confirmation. Is this something that will be added to Arnold anytime soon?

 

I'm working for a client that has switched from Mental Ray to Arnold and this part of the pipeline is very important to there work.

Message 7 of 9
dmzscripts
in reply to: dmzscripts

So the situation has progress a bit. I turns out that in 3ds max 2021 the AO and objID do render transparency correctly as AOVs. 

Scene.png

In the left image you see an ao aov rendered in 2021 (transparency of the image texture comes through correctly)

The right image is the same file rendered in 2023 (transparency seems to be reduced to either fully opaque or transparent)

 

Whats going on?

 

 

Message 8 of 9
dmzscripts
in reply to: dmzscripts

This solution comes straight from Autodesk.

 

In the Render Setup dialog turning off the preview(AA).

Preview(AA).png

For me this is sufficient when rendering with the standard Render frame buffer.

 

If you are using Arnold RenderView, turn of Progressive Refinement.

Progessive Refinement.png

After changing these settings the AOV render should work as expected.

Message 9 of 9
Stephen.Blair
in reply to: dmzscripts

straight from Autodesk = me 😉

This is a known issue with AOV opacity blending in the Arnold Render View, and we have a ticket logged for it.

 

On this thread, I was focused on transmission and forgot about opacity.



// Stephen Blair
// Arnold Renderer Support

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