Help with Matte material

[Cesar R]

Guys,

 

back in 200X I was playing with the the Matte material to superimpose a 3d model onto a background and cast shadows and all. Today I have the need to do a render of a building design of mine against its site. I did small test scene just to go through the motions and learned and few things about the "mental ray" Matte/shadow material.

 

I did some reading online and everything seems to work fine. However, When I render with a MR daylight system and the MR exposure controls, I either get a black plane, or a "dark" area (where the plane is)

 

Attached is the scene saved in ver 2010. If someone would be kind enough to tell me where I am dropping the ball I would appreciate it.

 

I was not able to insert the jpg (too big) but feel free to use one of yours.

[Cesar R]

24 views. no one knows?

[Matt McDonald]

http://mentalraytips.blogspot.com/2008/02/why-does-mental-ray-render-my.html

[Cesar R]

Thanks for the link. So I still do not understand. Do I need to know the exposure of the photo and match it with the exposure controls?

[pixelperfectg]

Do I need to know the exposure of the photo and match it with the exposure controls?

Well, kind of. You're using the daylight system that far exceeds a 1.0 intensity value (assuming 32bit frame buffer) of a .jpg backplate. You'll either need to adjust the exposure control settings accordingly, or adjust the intensity of the mrSun/mrSky down to 1.0 to match the backplate, or use a different light source like a mrAreaSpot with a matching HDR environment, etc.. As with everything in 3ds Max there are many ways to get to the same end result.

 

FWIW I made you an example scene of a comp with the MSR material, backplate, using the daylight system. I used an adjusted unitless exposure control value to try and match the intensity of the mrSun. However, as I already stated there are a number of ways to handle the intensity mismatch issue when combining the HDR mrSun with a LDR backplate image.

 

Scene output:

 

DOWNLOAD FILE