Shadow Catcher Bug

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Any of you Thea for Rhino users out there having issues with a ground plane assigned as a shadow catcher material?

I often render a scene and export as PNG with alpha so the background (IBL) & ground plane (shadow catcher) is removed.This allows me to composite a final image together in Photoshop.

In Thea for some strange reason the background image (IBL) is baked into the shadow catcher material and means you cant export an image to composite in Photoshop later....... does anyone else out there find this weird?

In all other rendering applications I have used in the past this is a standard feature.

let me know if you are having the same issues and hopefully if enough of us experience it the Thea team will fix it.
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Rombout
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have setup the mesh correct? It doesnt need to have any material, just delete everything and check shadow catcher. I do believe indeed the plane is added to alpha though, but you could add a mask id to delete it in post.
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I tested the issue you mentioned out of curiosity. It seems to that the Alpha channel does include a ground plane, even if it is assigned with a shadow catcher material. But the IBL environment looks normal and I did not seem any problem with it.

If you just need to Photoshop those rendered objects, why not just turn off the ground plane and make a separate render?
2017-10-25_090332.jpg
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Rombout
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How can you change the background color in your example?
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Rombout wrote:How can you change the background color in your example?
I just used a JPEG of blue color for background image. There is a function in Thea for Rhino to do so.
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ah yes i know, but he wants to be able i guess to do it outside photoshop. I think best option is use mask id and shadow channel. together with alpha.

See attached;
- color channel
- Shadow channel
- Mask ID channel

Then in photoshop or other edit application use the mask ID as a mask on the shadow channel. then set to multiply. This way you can change the backdrop to any color in post.
Attachments
Mask channel
Mask channel
SHadow channel
SHadow channel
Colol channel
Colol channel
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here's example, changed bg to orange. did soft manual high light paint in a layer above
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color-changed-.jpg
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Hi Thea Forum, thanks for your responses, there are so great tips in there.

Im not sure I have explained my issue clearly enough as some of the suggestions I cant get to work.
I have uploaded a screen cast to you tube illustrating the issue which should clear thing up nicely.
you can view the screen cast here https://youtu.be/UOyh5nnK-JM
let me know your thoughts
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Rombout
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aha so you want the reflections as well. I think best option here is use mask ID on the water surface so you have a starting mask. Then overlay the water part with the reflection and use the mask id to set the mask on the water. This will cut out the people and the boat. Than manually paint more in the mask where the sand meets the water. This way you only see the reflections and the shadows. Its quite easy to it with masking in photoshop or any other software. You can even export the shade and reflection as channel as well do the same trick. Than you can make one of these or both even stronger visible if you like/need
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PS in the start of the screencast the refelctions and show look much nicer i think. You can also use these cause you would see part of the boat underwater as well.
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