Shadow catcher to match live action

[cgartashish]

Hi,

I want to place a 3d object onto a real background and match the lighting. I am using PBR rendering option in Mantra. I am having a hard time to find out a shader/material that only recieves shadow and do not cast any shadow. I have tried shadow matte shader but it renders completely black. Can anyone please help me. I would also appreciate if anyone can please suggest me how to change the properties of an object as to only cast shadow or receive shadow and similar components.

Thanks

[carlo_c]

Check the alpha of the shadow matte render, the shadow should be living in there!

Edited September 8, 2016 by carlo_c

[cgartashish]

4 hours ago, carlo_c said:

Check the alpha of the shadow matte render, the shadow should be living in there!

Thanks, I found the shadow in alpha channel as you suggested, but I am still facing the same problem, in my render view and mplay, the grid with shadow matte still renders black but the shadow is present in the alpha channel. Is there any way that I can see the shadows directly in render view? Please let me know.

Thanks again.

[carlo_c]

What you'd usually want to do is render the shadow separately and comp it back in so you can fine tune it to the shot. The black rgb isn't a problem as you have the shadow in the alpha and can do whatever you need to with it in post such as grading it to match existing shadows in the plate.

[cgartashish]

4 hours ago, carlo_c said:

What you'd usually want to do is render the shadow separately and comp it back in so you can fine tune it to the shot. The black rgb isn't a problem as you have the shadow in the alpha and can do whatever you need to with it in post such as grading it to match existing shadows in the plate.

Thank you, actually I will render a separate pass/take for the shadow and use it in comp later, but just for the sake of instantly viewing the result in render view/mplay, is there a way to setup the render in such a way that it automatically renders the scene with the shadow and not just a black object for the shadow catcher. Just for viewing sake and when I am satisfied with the result then I would set up a renderer with different passes for comp.

Thanks again   

[carlo_c]

I think the way I'd do that is to set up one take with the normal material and a take with the matte, then you can test away with the normal material. When you need to render out the shadow just switch takes and you're good to go.

Just put this basic scene together to illustrate what I meant in case it didn't make sense

shadow_matte_take.hipnc

Edited September 9, 2016 by carlo_c
added scene file

[cgartashish]

On 9/9/2016 at 0:11 PM, carlo_c said:

I think the way I'd do that is to set up one take with the normal material and a take with the matte, then you can test away with the normal material. When you need to render out the shadow just switch takes and you're good to go.

Just put this basic scene together to illustrate what I meant in case it didn't make sense

shadow_matte_take.hipnc

Thanks a lot for your help.