How to remove floor but keep shadows?

[it_refplus]

I'm using V-Ray Render Elements to remove a floor but keep shadows but I'm not getting the expected results. I would need a step-by-step tutorial on this subject, including opening the image in Photoshop, etc. Can anyone one point me to such a document/video?

Thanks in advance.

[sirio76]

Can you show exactly what are you trying to achieve?

[aleksandar.kasabov]

Hello it_refplus,

Are you trying to create a shadow catcher? If that is the case, you can do that by adding a plane and then adding a V-Ray “Object Properties” tag to it. After that, you need to enable “Matte Surface”, “Shadows” and “Affect Alpha” options. You also need to set “Alpha contribution” to -1. Please check the following video.

You can find more information about the V-Ray Object properties tag here.

Please let me know if that is what you are trying to achieve. Thanks.

[it_refplus]

Very simple actually. I have an object on top of a floor (plane). There is a light on top that's projecting a shadow of the object onto the floor. My goal is to obtain an image of just the object and the shadow, without the floor. So, I want to subtract the floor from the image. I added an Object Properties V-Ray tag to the floor and gave it Object ID 1. Then, I opened the V-Ray Render Elements window and added an Object ID (Object Select) and also gave it ID 1. In the Render Settings, I check Multi-Pass and added Post Effects. This doesn't seem to be working. Please find below the C4D file of this project.

[it_refplus]

Yes, Aleksandar, I'm trying to achieve a shadow catcher. I tried your technique, but all I got was a white image. What Render settings should I use? This is definitely not user friendly.

[aleksandar.kasabov]

Hello it_refplus,

Simply adding the V-Ray Object Properties tag to the plane, enabling the “Matte Surface”, “Shadows” and “Affect Alpha” options, and setting the “Alpha contribution” to -1 will result in shadow catcher. Please check this video.

In that example, I saved the image as .exr and imported it into Photoshop. If you want to save the output as PSD, once you open it in Photoshop you will need to use the Alpha channel and add it as a mask. Please check this video.

I hope this is of help.

[it_refplus]

Thanks. That's actually what I did and it worked. However, I thought it would save the Photoshop file with a layer for the floor, one for the shadow and one for the object. I would then just need to deactivate the floor layer. I guess it doesn't work this way. Thanks again for your help.