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We're currently looking at several renderers and would like to know some details about V-Ray's handling of mattes.
Specifically, is there some way to have matte objects receive shadows from non-matte objects but NOT from other matte objects?
Imagine we have a scene that is going to be composited over an existing plate (a table with a few objects on top of it). In this scene I have three objects:
1. A plane (matte for the table top)
2. A box (matte for a cereal box on the table)
3. A sphere (non-matte, CG element to be added)
In the original photo, the box casts a shadow on the table.
During the animation, the sphere flies through an area of space that is in the box's shadow, and then lands on the table (outside the box's shadow).
Based on my experience with Max's default matte material, if I configure the box and plane to cast and receive shadows, then:
1. I get the cube's shadow on the sphere (correct).
2. I get the sphere's shadow on the plane (correct).
3. I get the box's shadow on the plane (incorrect).
I say "incorrect" because that shadow is already in the photo, and rendering it will result in a darker shadow when we composite the resulting image over the plate.
If I configure the box to cast no shadows and the plane to receive shadows:
1. I don't get the cube's shadow on the sphere (incorrect).
2. I get the sphere's shadow on the plane (correct) but it adds to the real box's shadow already on the photo (incorrect).
3. I don't get the box's shadow on the plane (correct).
If I configure the box to cast shadows and the plane to not receive any shadows:
1. I get the cube's shadow on the sphere (correct).
2. I don't get the sphere's shadow on the plane (incorrect).
3. I don't get the box's shadow on the plane (correct).
So, what I'm looking for is a way to get those 3 effects. The simplest way to explain it is that I don't want matte objects to receive shadows from other matte objects (but I still want them to receive shadows from non-matte objects, and to cast shadows on non-matte objects).
Is there some way to do this with V-Ray, other than creating two copies of every light and manually excluding objects?
Thanks in advance,
M.T.
Specifically, is there some way to have matte objects receive shadows from non-matte objects but NOT from other matte objects?
Imagine we have a scene that is going to be composited over an existing plate (a table with a few objects on top of it). In this scene I have three objects:
1. A plane (matte for the table top)
2. A box (matte for a cereal box on the table)
3. A sphere (non-matte, CG element to be added)
In the original photo, the box casts a shadow on the table.
During the animation, the sphere flies through an area of space that is in the box's shadow, and then lands on the table (outside the box's shadow).
Based on my experience with Max's default matte material, if I configure the box and plane to cast and receive shadows, then:
1. I get the cube's shadow on the sphere (correct).
2. I get the sphere's shadow on the plane (correct).
3. I get the box's shadow on the plane (incorrect).
I say "incorrect" because that shadow is already in the photo, and rendering it will result in a darker shadow when we composite the resulting image over the plate.
If I configure the box to cast no shadows and the plane to receive shadows:
1. I don't get the cube's shadow on the sphere (incorrect).
2. I get the sphere's shadow on the plane (correct) but it adds to the real box's shadow already on the photo (incorrect).
3. I don't get the box's shadow on the plane (correct).
If I configure the box to cast shadows and the plane to not receive any shadows:
1. I get the cube's shadow on the sphere (correct).
2. I don't get the sphere's shadow on the plane (incorrect).
3. I don't get the box's shadow on the plane (correct).
So, what I'm looking for is a way to get those 3 effects. The simplest way to explain it is that I don't want matte objects to receive shadows from other matte objects (but I still want them to receive shadows from non-matte objects, and to cast shadows on non-matte objects).
Is there some way to do this with V-Ray, other than creating two copies of every light and manually excluding objects?
Thanks in advance,
M.T.
