matte-shadow material

[bobo_cg]

I couldn't find a way to produce a rendering without background (I can use an alpha channel, of course), but with the shadows of the objects in the scene projected on an invisible plane. This is for image compositing.
Could someone solve this problem?
Thanks
Roberto

[dalomar_cg]

Re: matte-shadow material

matte shadow materials are on wishlist for the next release. At the moment, the easiest way to get around this is to make a map that approximates the shadow, and then put that in the alpha slot for the groundplane material.

[bobo_cg]

Re: matte-shadow material

Ok, thank you; I'll try to do it.

[Micha_cg]

Re: matte-shadow material

I couldn't find a way to produce a rendering without background (I can use an alpha channel, of course), but with the shadows of the objects in the scene projected on an invisible plane. This is for image compositing.
Could someone solve this problem?

OK - I do it. ;D

* Create a plane material and disable "double-sided" at the VfR material. Now, you can render the plane from the bottom view - you should see the shadow.
* Crop the image so that the rendered plane can be used as texture.
* Create a new material, set color complete black and set the previous rendered ground texture as transparency map.

Now, your ground plane should be show a shadow only, nothing more. Maybe you need a little bit fine tune the texture at photoshop.

Here a quick test - background is added in photoshop.

[Gijs]

Re: matte-shadow material

Hi Micha, what a brilliant workaround! very smart.

[Micha_cg]

Re: matte-shadow material

My goal is to find workarounds for all missing features.

The problem was very interesting for my work, because since a long time I try to find a way to hide the groundplane at reflections. Object/material based visibility options are at the wishlist since a long time, an important feature for product design renderings, but the implementation seems to be a problem.
Often I need a white ground with shadows, but no visible white ground at the reflections. And this workflow is a good workaround for this problem, like the chrom Mini show (PNG image with transparency).

[Micha_cg]

Re: matte-shadow material

... and the ground texture can be used for the Rhino rendered viewport - here a screenshot with "baked" softshadow + hardshadow.

[dalomar_cg]

Re: matte-shadow material

Looks good Micha....

[han3d]

Re: matte-shadow material

thanks for sharing

[LeoBonilla]

Re: matte-shadow material

so the how big should it be the size of the model right, so we have to have two thing, model and the plane below with the shadow texture?

put some more explicative screenshots so people like me can understand! jejejejejej

[schultzeworks]

matte-shadow material : need it!

You gotta make the matte-shadow work in the next release. I vote we move it from the "wish-list" to the "prayer list."

[dalomar_cg]

Re: matte-shadow material

If we had a prayer list then it would be as long as the wish list. Consider the matte shadow material on the "VfR2 won't come out the door without this feature" list