I'm not very bright when it comes to technical stuff and I'm having an issue that I hope has an easy solution. What I want is to have the shadow of an item appear on a backdrop but without the item itself showing in the final render, only the shadow itself. I tried playing around with the item outside the camera range but the shadow is distorted and not as crisp looking as I want.

Is there a way to do this without mucking around with layers? I just don't find technical stuff intuitive so a clear simple explanation would be deeply appreciated. Thanks in advance.

An example would be for instance, a housecat would show in the finished render but it's shadow would be that of a lion. Or say a regular hand in the render casting the shadow of a claw. Is that possible?

Quote - An example would be for instance, a housecat would show in the finished render but it's shadow would be that of a lion. Or say a regular hand in the render casting the shadow of a claw. Is that possible?

 

Render two images (cat, hand) separately and composite in Photoshop (or similar app).

Doing this will allow you to play with the exact transparancy you want as well (for the shadow).

-AniMajik

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My problem is that I can't have what's casting the shadow in the scene at all so getting a realistic result is problematic.

animajikgraphics' solution uses two scenes - one with the thing you want to cast shadows, one with thing you want to be visible. If you render the latter without a background object and save it as png or tiff you can just dump it on top of the version with the shadow. The other option is to use pwCatch on the shadow-casting object, set to cast shadows and transparent, with the thing you want visible present but set not to cast shadows.

Quote - The other option is to use pwCatch on the shadow-casting object, set to cast shadows and transparent, with the thing you want visible present but set not to cast shadows.

Oh I like the sound of that. The Marketplace search doesn't yield any return for "pwCatch" though. Where do I find that? It's a plugin?

Once again, I appreciate your and the other responders help very much. Thank you.

Oh I found it on DAZ. Now to figure out how it works! Thanks again.

Tisket, This should help if I understand what you want to do.

http://www.youtube.com/watch?v=qo2OVy9tf8E

That's a really good video showing how to use the shader mixer.  In this case I think you might want to try something like this:

http://www.daz3d.com/forums/viewthread/17295/

Apply the UberSurface shader (which now comes with DAZ) to all the surfaces in the object you want to cast a shadow but be invisible.  Then turn on the Phatom on/off switch.  It's easy to do this in the surface panel.  Just select the object and all it's surfaces, apply the ubersurface shader then scroll down and turn on Phatom.

Then add the item you want to be visible to the scene.  For it find the option so that it doesn't cast shadows.  Place it on top of the shadow casting item you setup.

If you do that you can have an invisible item casting a shadow.

Attached is a quick test.  I applied the UberSurface to all of V4 and turned on Phantom.  I then added the bear to the scene and set him not to render a shadow.  I added a plane to the scene and one distant light with raytraced shadows.  It works with shadow maps too, but I'd recommend raytracing for these kinds of effects.

 

 

-Matt

You guys are fabulous! I'm going to play with those techniques this weekend. Extremely useful tips and suggestions.

Thanks, I always forget about the Phantom option with uberSurface.