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Texture with transparency should cast shadow on object

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Michael Ruepp
Texture with transparency should cast shadow on object
on Aug 15, 2006 at 11:58:41 am

Hi out there, i am a maya newbie, and need some help:

I did an simple earth model (Sphere with texture on it) and want to name different towns on the earth. So i draw a new texture with the Text and created a second sphere (slightly bigger than the earth). I parented the spheres and put the texture with the names of the towns on the second sphere.

Then i created a alpha tga and connected it to the transparency input of the material.

Now the names of the towns are like flying over the earth.

1. How can i create a shadow of the text, casting on the earth below? Is this possible or do i have to model the text in 3d?

2. I animated the earth, camera is flying in to the towns. I want to render out the earth and the text layer in seperate passes. How can i make the earth invisible, but use it as stencil to make the text, which is floating behind the earth sphere, make also invisible? Now, when i render the text layer by switching the earth sphere "Primary Visibility" in Render Settings to of, the text behind the earth is always visible, so i am not able to composite the Text layer over the earth layer.

3. I use a 2700x1400px Texture, so i can fly in to the town/text in a resolution, fitting to 720x576px (Pal). But the render Times for this simple model (650Frames in 10hours) are so big. Is there an other solution, maybe switching textures or something to speed up render times?

Lots of thanks for answering to my questions,


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Steve Sayer
Re: Texture with transparency should cast shadow on object
on Aug 15, 2006 at 2:24:40 pm

1. You can create a shadow by enabling raytraced shadows; raytracing will accurately calculate shadows based on partly-transparent objects. However, raytracing often increases render times significantly. Another solution might be to simply use the same texture map to affect the Diffuse attribute of your earth texture. That way there will be fake shadows underneath each piece of text.

2. Assign the Use Background shader to the earth for that layer/pass.

3. I'm not 100% sure about this, but I think that your texture size is probably not the cause of the long render times. As a test, try replacing it with a much smaller texture--or removing it entirely--and rendering out a few frames. If the problem is not your texture, we will need more info to help you troubleshoot--are you using motion blur? Depth of field? Raytracing? Etc...


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