Render shadow that's been casted by some element

[jovcem]

If I have a scene like this I would like to render the shadow that the red box casts to the gray element,
but without the shadow that the gray element casts to itself.


If I disable cast shadows of the gray element I get something like this:

But it still got some GI on the render, if I disable to receive GI I get something like this, which is pretty close to what I need, but the GI is off so the shadows are more darker and in some cases incorrect.

I know that this can be achieved with another pass where I render only the gray element and then in post divide both shadows but Im asking if there is some way to do it in one pass.

[jovcem]

Does anyone knows something..
I want to render shadow that a element casts on another element wihout the self shadows of the element that receives the shadow, and I want to do this in one render pass.

[hermit.crab]

I suppose you meant to upload some images illustrating the issue (judging by 'like this:'). Could you try to do that again, since it's hard to understand what you mean and what you're trying to achieve?

[jovcem]

I suppose you meant to upload some images illustrating the issue (judging by 'like this:'). Could you try to do that again, since it's hard to understand what you mean and what you're trying to achieve?

By 'like this' I meant the image bellow the text.
Can you see images in the post?

[hermit.crab]

By 'like this' I meant the image bellow the text.
Can you see images in the post?

No, I cannot. Could you try attaching them again?

[jovcem]

No, I cannot. Could you try attaching them again?

Here is an image describing the problem, its from blender but Im having the same issue. link to the site


I want to render matte shadows that are being casted from other objects but without the shadows that the object cast on itself, and I want to do this in one pass.
I can do it with multiple passes, but my question is if it can be done with one?

Thanks

[hermit.crab]

I suppose you simply want to render (correct me if I'm wrong) the shadows that one objects cast to another. You can do that by enabling the matte object properties of the object that will act as a shadow catcher.

You may use either of the following methods:
1. Clicking the 'Shadow catcher' button in the V-Ray toolbar
2. Setting the matte properties manually through the V-Ray properties of the object
3. Applying a VRayMtlWrapper on the object and enabling the matte surface option

You can read more about the mentioned properties in the technical documentation here:
https://docs.chaosgroup.com/display/...atteProperties
https://docs.chaosgroup.com/display/...atteProperties

[jovcem]

I suppose you simply want to render (correct me if I'm wrong) the shadows that one objects cast to another. You can do that by enabling the matte object properties of the object that will act as a shadow catcher.

You may use either of the following methods:
1. Clicking the 'Shadow catcher' button in the V-Ray toolbar
2. Setting the matte properties manually through the V-Ray properties of the object
3. Applying a VRayMtlWrapper on the object and enabling the matte surface option

You can read more about the mentioned properties in the technical documentation here:
https://docs.chaosgroup.com/display/...atteProperties
https://docs.chaosgroup.com/display/...atteProperties

Yes thats what I do, but the object that catches the shadow also catches shadows from itself, I want it to catch shadows only from other objects.

[hermit.crab]

Make sure the 'No GI on other mattes' option is turned on.

If the shadows (of the matte object itself) are still present, it would be best to send a sample scene (where the issue occurs) to support@chaosgroup.com for further investigation.

[jovcem]

Make sure the 'No GI on other mattes' option is turned on.

If the shadows (of the matte object itself) are still present, it would be best to send a sample scene (where the issue occurs) to support@chaosgroup.com for further investigation.

Turning on 'No GI on other mattes' works in some cases, but not every time.
And there is no issue its just the way it works.
If I want the element with No GI on other mattes = ON to cast shadow on some other matte, it just wont work, it wouldn't receive self shadows but it wont cast shadows, sometimes I want it to cast shadows to other mattes.
I hope you understand me I guess I will have to find a way with multiple render passes.