Transparency Problem (MAYA ONLY NOT MAX)

[JustinTuaylou]

Hello:

 

I've run into an issue with Mental Ray transparency (This is a Maya-specific problem, but I posted this in the Mental Ray forum also).

 

When I use Mental Ray to render a Mia_x material with the transparency attribute mapped, one of two things happen. If the map is procedural, the transparency is fine in both the hypershade and the render. However, when the map is a bitmap image, I must first make the connection to the attribute by hand in the hypershade because it doesn't happen by just clicking the slot, and then the transparency doesn't show up in either the hypershade or the render.

 

I hope that makes sense, I have attached several screenshots to show what I mean. If anyone knows what is happening, or if I am making the connection wrong, please help. I suspect this is a render setting, but I don't know.

 

Thanks,

 

Justin

 

P.S. This also happens when I render a standard material with Mental Ray.

[JustinTuaylou]

After a lot of trial and error, this is what I have found, someone please correct me if this is wrong:

 

Connecting the OutColor of a Bitmap to the Transparency attribute of a standard material works and will work correctly in the Render. However this doesn't work with a mia material. I am not given the option (even in the connection editor) to connect the OutColor of the bitmap to the Transparency of the mia shader. The only option I have is to connect the OutAlpha of the bitmap to the Transparency.

 

In other words:

Standard Material - Connecting OutColor of any B/W image file to the Transparency attribute of the shader works.

 

mia Material - Connecting OutAlpha of an image with an Alpha Channel to the Transparency attribute of the shader works.

 

Neither connection is the default made by simply clicking the transparency slot in the attribute editor, this must be done manually.

 

Is this right? Are there two very different approaches to this depending on the material and the renderer used?

 

Justin

[Chucky]

Use the cut out opacity for your bitmap

[JustinTuaylou]

Thanks, I forgot about cut out opacity since I started using maya, but you still can't map an image with no alpha channel to it (like a jpg). It seems that it doesn't use the black and white of the RGB, but of the alpha. I was confused because I'm pretty sure that you could use a jpg with Arch & Design in max, oh well just a different workflow.