@aerilius said:

But: SketchUp does not recognize the opacity in transparent texture images (because it's separate from the opacity slider), so you could apply a material with a completely transparent png image to all entities of which you want to see only shadow, like in this example.

I have the exact same problem with pipogianni,
I am trying to get some tree shadows from png tree images (with transparent backrounds) in my model, without rendering the png tree plane itself.
I only want the shadows, so I can add the trees later with photoshop.

The example that you posted here seems to manage exactly that,
but i can't figure out how. !
Can anyone please explain what am I looking at in this model?
How are the two lateral shadows created without the smiley faces being displayed?