Please help with Matte material

[chad]

I know this has been discussed at length, but I can't seem to figure out how/if this can be achieved:

I am working on a photomatch that is basically adding elements (awnings, shutters, etc) to an existing building. To add the shadows of these elements to the rendering, I built a wall in VIZ, made it a matte object (alpha contribution= -1.0, shadows and effect alpha are both checked.) The result is below:



The problem is the matte object is adding shadow to the scene because of the GI. If I turn off GI for the object, the result is below:



How can I achieve the soft shadow effect in the first image without having the matte wall object effect the scene (as in the second image)?

Thanks very much,

Chad

[chad]

anyone?

[jujubee]

can u throw a vramat wrapper around the object- then turn down the recieve GI settings? I think that may work.

there's one other place you can try this- in the render dialog- vray: system\object settings. select the wall/s and urn off recieve GI.

or vice versa (meaning apply these steps to the shades.) Let me know if this works for you.

-jujubee

[chad]

jujubee-

That's what I tried to do with the second image. As soon as I turn off "receive GI" for the object, the shadows are all black.

-Chad

[shytigercp]

re

I had the same problem with a project...it was tough. I had to work around it by modeling a general orthoganal shape of the building. Then I rendered the accents casting shadows on the box building I created using cebas PSD manager. I split up all the elements in the scene, ie. shadows, roads, trees, & etc on different layers. Then I rendered the camera match....the rest was PS.
I was stressed for time as always and didn't have time to fiddle around.

This might not be a good solution for you...but it worked for me.

[jujubee]

This may be an obvious question- but did you turn off recieve shadows for that object?

[chad]

jujubee- No- I want shadows on the matte object, I just don't want them to be pure black. If I was using the scanline render, I could apply a matte/shadow material to the wall, then My alpha channel would contain soft shadows.

What I can't do in VRay is the same thing. I either have soft shadows with my matte object in the alpha channel, or I have hard black shadows with my matte object not in the alpha channel. What I would like is soft shadows with no matte object in the alpha channel.

shytigercp-I had to do something like that previously. I was hoping that there was a way that I didn't have to.

-Chad

[roppin]

try to render it to a black background and composit it afterwards!