Matte Plane

[rajdarge]

I have a scene with multiple 2d image planes that have opacity maps on them. The background is another of those image planes with no opacity.
Its very crude form of camera matching. But its in a toony kind of image.
So I wanted to create a shadow one of the foreground 2d objects with a shadow catcher. The material used for the plane is a vraylightmtl with opacity map with "exposure correct on" and the opacity map multiplied ...
So I thought - add a plane below the image plane, give it a vraymtl, then click matte object, vrayalpha -1.0, shadow and alpha boxes ticked
the alpha channel looks nice and all.
But the RGB channel has a darkened square where the shadow catcher is. I tried turning off "visible to camera" but then it didn't render at all. I have tried turning on and off caustics, GI, using a null material, using vray override mtl,
I've uploaded 2 images to show the problem. Sorry for the glamour image of the girl, but I literally grabbed the first images that I could remember that had a good quality image mask for them, and I was a glamour photographer for 5 years.

anyone know how to have that square shadow just display the shadow part? and to have it show as just a darkened version of the background?
Raj

[thablanch]

That's exactly what the VRayMtlWrapper is there for

Instead of playing with exclusion and object properties, everything is there in the material (your floor material in this situation)

[rajdarge]

I tried the vraymtlwrapper material and it gave me a pretty similar result. It still needs a base material in order to render the alpha channel properly . Using a vraymtl as the base mtl i get the same result��

[rajdarge]

Ok so these are the things I've tried: adjusting object properties to recieve and cast shadows, render occluded objects, object visibility.
I've tried changing vray settings on material applied to the shadowcatcher object white diffuse, 0-100% transparent, 0-100% reflective turn off reflections, refractions, double-sided, changed the opacity mode to normal, energy conservation mode, applied a black vraycolor to opacity map, turned off gi in both vraymtlwrapper, and vray properties
I have a work around which requires render in multiple passes with different settings and then in photoshop using a curve with the alphachannel on the background image. Not very useful for animation....
I did read somewhere about using state sets to to multipass renders. Also I haven't fiddled with gbuffer values though I'm not sure how that would help either. The final direction I guess would be vrayrenderelements. But I don't see anything but a multipass render solution that I was trying to avoid.
I will try and upload a scene that has none of my custom plugin data as Its not released yet and therefore will unlikely load without it.
Raj
VrayTestFile.zip
a g rated version in this file this is a render with the disappointing results
can anyone get it working ?

[svetlozar.draganov]

The Matte result is actually properly calculated, yes it doesn't look as it is but let me try to explain why.
Matte result in V-Ray as well as in any other render engine works against the background, in your scene you've placed the textures over planes in the scene not in the background.
What matte object renders is what is in the Environment slot not objects behind the matte-one.

Here I have tweak the scene by placing one of the textures in the environment slot and removing the planes:
Scene:http://ftp.chaosgroup.com/support/sc...TestFile01.max

[rajdarge]

Thanks for looking at the problem. I actualy started at that point with a texture in the environment map. However you lose motion blur and bokeh for this. But also you cannot have multiple background objects at different to the camera giving them different amounts of blur. Also you affect the lighting for the render, sometimes it looks good, but sometimes it breaks the illusion. I had reached the conclusion that a multipass approach is the only one thats going to work. I'm trying to write a maxscript to help with "2.5d" animation mixed with correct camera physics and with some actual 3d objects. To give the illusion of a 3d scene even in a toony world needs shadow and colorcast to fool the eye. Or so i have thought

[rajdarge]

I have found a multi-pass solution:
render a separate background image to a file and use it in the environment map.
however with maxscript i don't seem to be able to use

local tempBitmap = render camera:Compositing.curCamera vfb:false outputfile:(MPSDir+"EnviMap.png")

i have to use this:

max quick render
vfbcontrol #saveimage (MPSDir+"EnviMap.png")

is this the only way to get image to render with vray?
I tried searching docs and forums and got little.

[svetlozar.draganov]

Like mentioning before Matte objects operates only with Environment map, their purpose is to render CGI against real footage.
You are after for something totally different that's why out-of-the-box solution doesn't work.

I am glad to hear you figure it out and I'll try to find someone from our team who can help with the MaxScript part since I am not really into scripting.