proper matteshadow shader accounting for correct shadows and reflections

[mts]

Hello there,
I am looking for a way to create a matteshadow shading network to use for my dummy floor objects when rendering 3d objects for integration into a backplate - something like the mip_matteshadow shader for mental ray, just for VRay. When searching the forum i read that many people seem to use a Material Wrapper for catching the shadows together with a VRay Light Mtrl to project the backplate image onto the geometry for reflections and indirect lighting of the 3d objects.

This works to some point, but my 3d objects don't reflect their own shadows.

I am also looking for a way to have the floor reflect my 3d objects. In one Thread Vlado suggests to use a Vray Blend Mtrl in additive mode to add a reflective coat to the VRay Light Mtrl. When doing so my floor indeed reflects the 3d objects but not in a way according to the laws of energy conservation (the reflection only gets added to the backplate image while they would have to be blended in some way). Furthermore my floor not only reflects the 3d objects but the environment as well which is a thing I would like to avoid.

To clarify my issue I attached an image of a test scene (please ignore the fact that the camera position and focal length are not correct). Can anyone give me a tip how to make a proper shading network? I would like to render everything within one pass.

Any help is appreciated,
thanks!


[/INDENT]

[RobPhoboS]

Just thought I'd chip in and request for it to work more like mip_matteshadow as well.

There are some more thoughts and info here which I think are related:
http://www.chaosgroup.com/forums/vbu...ecom-Farmhouse
http://www.chaosgroup.com/forums/vbu...VRayMtlWrapper

[vlado]

Are you looking for something like this?



Best regards,
Vlado

[mts]

Yes, Vlado. If the matte material of the table does not reflect the environment, provided there is one, but only the sphere, that is exactly what I have been looking for. Any hints how you got the sphere reflecting its own shadow? You rendered only one pass didn't you?

[vlado]

I'm attaching the scene here. I have environment override attributes on the wrapper material (so that I can put a projection texture there, which will appear in the reflections in the sphere), and also environment override attributes for the base material inside the wrapper (so that I can get black environment in the reflections on the plane).

Best regards,
Vlado

[RobPhoboS]

Hi Vlado,

I'm just trying to get this shadowmap type of thing working again but failing to at the moment.
Is there any chance if you or someone else can explain what you've done in the above file ?

I'm struggling to get a piece of ground catch shadows/reflections that only shows those parts, it always looks darker where the geo is (thus making it look obvious what it is).
I'll try and post some screen shots up if that doesn't make sense.

[vlado]

If you can post a scene that I can modify, it would be best.

Best regards,
Vlado

[RobPhoboS]

If you can post a scene that I can modify, it would be best.

Best regards,
Vlado

Will do once I get home from work.
Although I downloaded your scene that you posted above, and I just popped a jpg from a sequence into both file nodes, this works fine. However, I couldn't understand where the projection&vraymat got plugged into, I'd presume it's the ground but I just got confused
Each time I selected that vray material in the hypershade, right clicked and hit 'select objects' it didn't select anything (and I couldn't work out where to plug it into).
I also didn't understand why we are required to use a vray material/environment override.

[Refracty]

I am new to VRay and I am trying to get reallisic Shadows and Reflections on top of an HDRI backplate.
By using a Wrapper Mtl the shadows come out nicely but when increase the reflectivity of the Wrapper node then the HDRI background (through dome light) is reflected as well.
Of course that is what I don't want.
First I thought I can stop this behaviour by unlink the ground plane (with Wrapper Mtl assigned) from the dome light, but then there are no shadows casted as well of course.
Is there a simple way to bring shadows as well as realistic reflections on a HDRI background without using render layers?
If there is no other way then render layers, what is the most straight forward solution for reflection layer (on ground plane)?
Using a black glossy material override for the ground plane and black matte materials for the other objects of the scene?