I saw somewhere (and now that I need it can't find it back) a tutorial on shadows talking about making an object "resist" or not accept shadows.
How do I make an object, like a backdrop that is too close to the scene not accept shadows?
I need and want the shadows elsewhere, just not on its surface.
Is there a way to turn off shadows for a particular surface?

Thanks!

I think this is what you mean. Select the object - the backdrop - and in the Properties menu, uncheck the box that says "Casts Shadows". Shadows can then be cast upon the object but it will not create shadows of its own.

there are many ways, e.g. in poser 8, zero all the channels in material room for surface which should not receive shadows, then attach img map or colour node to alternate diffuse.

No, you have it backward nekkidchicken...
I have shadows off already cast by the backdrop.  I don't want the characters shadows showing on the backdrop itself...  looks odd when Vicki's shadows are as tall as mountains...  :)

I think Miss Nancy may be on right track there, will have to try that.

Hi Miss Nancy,

This is an interesting topic, this is one of the things that I miss in Poser as I often need a surface to not receive shadows, in other applications there's usually a check box or exclusion dialogue for the surface or light..

I tried your suggestion regards zeroing all the material settings on the materials surface and using alternative diffuse,but it made no difference, shadows were still cast onto the surface that shouldn't receive shadows as though I'd done nothing to the shader.

If there's another way to exclude surfaces from receiving shadows I'd be gratefull for any advice too :)

 Of course this won't look right in all cases, but for backdrops it will often work if you set Ambient to 1 and a white colour, then plug the texture map into the ambient channel as well.

The ambient will override the shadows. BUT it will make the backdrop emit light if you use it with IDL. So in that particular case it's not a good idea.

I was not able to eliminate shadows that way either.  :(

Ok.  So what else can be tried?

Oops a daisy!

My apologies Miss Nancy, it does work :)

I wasn't getting the results at first due to my using a Diffuse node to plug into the Alternate Diffuse as a test, this still gave shadows.

I used a 2D Image node and Bob's Yor Uncle the shadows disappeared. Should have tried that first :)

@ c567591: The methods that miss nancy and TrekkieGrrrl mentioned do work, I have used them many times.  Exactly, how are you projecting your background image?  Is it on a one-sided square or is it a background image in the application?  Perhaps you could post a render of your problem.