Maya rendering issue

rube

I'm having a rendering issue that's causing all kinds of delays.

I need to render with mental ray and since I'm bring the renders into photoshop I turn premultiply off. But, I'm getting weird issues now with the edges of objects with alpha channels. Even when I disconnect the transparency from the material the alpha channel still 'bleeds' through in the render (but not the renders alpha channel) here's a pic that shows what I mean. Any thoughts on how to fix it would be appreciated. All textures are TGA with an alpha channel. Interestingly the issue doesn't show up if I use two images, one for colour and one for alpha. I can't do that though since I need to see the alpha in the viewport in order to set up my scenes.

[edit] I'm using Maya 2009, but I've confirmed the same issues in 2010.



rube

Cyrael

not really sure whats causing this issue, is it happeing in your compositing program or its just how it looks when you view the image? Secondly try outputting as .tif files.. It may be personal preference but 90 percent of the time I'll use .tif when outputting alpha and never had any problems with it.

larolaro

It's not because of maya.

I think its because you have another colour in the background, what you need to do is just have the solid colour you want, for example for the word "alpha" you would have only red in the RGB, The text mask then should only be only in the alpha channel.

Think about it like bleed, you have to give the edges a bit of room. The ugly fringe is a subpixel from the background colour when the alpha cuts it out.

---

Colour

---

Mask

---

Final

---

This is with just one image, plugged into the colour and transparancy.

rube

I'll try a tif, but I doubt that will fix it as it happens in all other formats I've tried. Even if that did fix it it's still not ideal since part of the spec for this job is that textures be delivered as TGAs (or a couple other formats that all have the same issue.)

In my example the colour is a solid red (aside from the blue COLOUR text) and it still happens. Make sure you're testing it with premultiply turned off. And actually rendering, not just looking at it in the viewport, there it looks fine.

[edit] tif has the same problem.

I'm pretty sure it *is a maya issue, not a texture problem, since there's no reason for the alpha channel to show up in a render when the material doesn't even have a connection to it.