View Full Version : Depth map shadows with transparencies without raytracing

05 May 2007, 01:42 PM
Well after a hour or so of searching ye' old archives, I have come to the conclusion that the particular issue I'm having with shadows in Maya 7 has yet to have a thread or it once did, in any case, I'm sure this isn't a duplicate.

So here's my dilemma:
With lambert files assigned 32-bit targas of trees applied to image planes-- so with the light set to raytracing I get proper shadows from the alpha channels in the textured planes and with depth map I predictably get shadows of opaque planes.
I understand this, yet I've heard that there's a way to get super-fast rendering by assigning a alpha file to a light source to get the appearance of raytraced shadows with a simple depth map.

After scouring the web, I have the solution for every other program except Maya-- Gnomon ( came close but I don't want extraneous geometry... I want to achieve the effect with one polygon image planes if at all possible.

If you would please, point me in the right direction whether the solution lies in the connection editor, an attribute setting, hypershade, or whatever... any help would be greatly appreciated. Faking raytraced shadows with depth maps would be greatest thing since rendered sliced bread...if only this mystery could be solved, some of my classmates once spoke of it-- it somehow works--- but how?

05 May 2007, 03:39 PM
'Standart Shadowmap' don't support transparency shadow.
Switch to 'Detail Shadowmap'.
Ofcourse I'm talking about mental ray.

05 May 2007, 06:56 PM
Thank you for the response, however the method you mentioned takes a few seconds longer than the traditional ray tracing.

What I'm interested in is the quickest rendering times by giving the scene less procedures, unfortunately mental ray has just as many computations as default raytracing if not more.

Is it possible to cast fake pre-made shadows with depth map? In other programs you attach the alpha of the overall shadows for scene to the light and the light references simply that file and doesn't perform it's own interpolations.

Again thank you, what you suggested works, but I've heard of a faster method where an alpha channel and a light controls the scene's shadows (unconventionally), the image planes don't really cast shadows, somehow the light fakes the appearance of casting the shadows. Because the shadows are referenced to a file, the rendering time is drastically reduced with these deceptive depth map shadows-- but how can you make a light reference an alpha channel to a file? Is this even the right way to go about it?

CGTalk Moderation
05 May 2007, 06:56 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.