Vray Mtl Wrapper and Light Sun issue

[dsp_418]

Hi there,

 

my first post here!

 

I'm looking at 3dsMax + Vray since a week or two now.

As I've just started to learn I'm facing some problems, today I'd like to ask your help about the following one.

I'm trying to make a simple composite, a basic greebled cube over a plane. I added a Vray Mtl Wrapper to the plane with the following settings:

Matte Surface, on
Alpha Contribution, -1.0
Shadows, on
Affect Alpha, on

As Base Material I'm using a Vray Mtl. By the way I've noticed that turning on the Refraction to maximum white prevent the cube to receive color reflection from the plane, even though I guess it's supposed to don't affect the cube.

 

On the plane I've also tweaked the Vray Properties as following:

Matte Object, on
Alpha Contribution, -1.0

 

It works until I add a Sun Light to the scene. Then I can see a smooth subtly gradient of light on the plane:

 

Without the Sun light:

 

Any hints?

Thanks in advance.

[Corey Beaulieu]

I'm not entirely sure I understand what you are trying to do, but I can tell you that you did setup the MtlWrapper coreectly. You could have also just made these adjustments in the VRay Propertins menu of the objects you want to matte. You really shouldn't have to make it fully refactive to remove color, but there is an occasional need to un-tick Receive GI.

 

As to any additional tips: You could also try selecting your Vray Sun, hitting the "Exclude" button, and then adding the plane that you see the color gradient on.

 

I hope this helps. I couldn't maximize your images to see what was going on in your image.

[dsp_418]

Thank you Corey.

 

The images aren't bigger than that, that's why you can't open them. It was meant to be just a detail of the problem.

Basically I'm just trying to compose the Cube over a picture.

 

I'll try your advice on the Sun Light as soon as possible, in the meantime I'm wondering if excluding the plane from the Sun Light will also prevent the plane to project the cube shadow.

 

If the images aren't clear enough I'll post bigger images soon.

 

Thanks!

[dsp_418]

I did some other tests and I'm noticing differences in case I use the Mtl Wrapper or not.

If I don't use any material on the plane, but just tweak the vray object properties, it seems to work:

 

As soon as I add the wrapper I see noticeable differences on the cube:

 

I've got rid of that gradient bleeding on the plane unchecking Receive GI. I had to do it both on the vray object properties and the wrapper material.

By the way, unchecking Receive GI takes the sun light color out from the shadow, it would have been nice to have a workaround for that and save the GI on the shadow.

[dmv79]

There are some workarounds for this issue. But what I'd do is set the base material color in your wrapper material to a neutral gray... even better would be setting it to something similar to what you'll composite with, and then play with it (saturation and brightness) to get the desired result. After all, color bleeding is a natural thing. I try to stay away from "artificial workarounds"... but it depends on your workflow. You could also play with the color mapping settings. Some of them can handle this bleedings but they also have other "side-effects" to consider. Other option is the vray material overide, where you can set a diferent material for the GI's response.

[dsp_418]

Thank you Daniel.

I didn't know about the material override, I'll take a look.