How Can I Render A Region Of Interest?

[charlesleguen]

Hi

I am wondering if Maya 7 has the ability to render what shake refers to as a "doman of definition" (after effects calls the same thing a "region of interest").

Basically, I have a CG airplane flying around the frame and I intend to comp it over a live-action background. I would save a lot of render time and processor time if I knew how to tell maya it only needs to respect the pixels in which there is actually something to render (the plane, in this instance).

If anyone can tell me how to get maya to only render "domain of definition", I would be most grateful.

Thanks

[davesrose]

So you're looking for a file format that can save transparency in the file....and not a seperate alpha channel?? If you look in photoshop, the only files that do that are jpeg, png, and gif. I suspect ROI was mainly used for websites that needed to save bandwidth. MR for Maya does have png as one of its file formats, but I'm not sure if it saves as transparency, or if it would save as an alpha channel. You'd have to experiment with png or psd. I suspect you wouldn't be saving any time rendering in Maya with that (since the 3D renderer is computing the depth of everything to begin with), so it may be adding a little bit of time. If you do find a way to keep transparency, let us know if it is faster to render in the compositing program! Personally, I've never had many slowdowns using an alpha channel in After Effects.

[phoenix_germany]

I think, what charlesleguen means is a region rendering. U can do this since M6.5.

mental ray for Maya batch rendering now supports user-defined region rendering. Use the new -reg flag, for example:

CODE
render -r mr -reg 0 100 0 100 scene.ma

where -reg 0 100 0 100 indicates the region to be rendered in pixels (left, right, bottom, top).
The above command renders the lower left 100 x100 pixel region of the scene.

But the time u preserve will be not much, because empty parts are rendered very fast with MR.

[charlesleguen]

Thanks very much -- "region renderng" is exactly what I am interested in.

But ideally I would want maya to figure out on its own where the region should be, especially if it is following an animated object. If I have a small plane flying around the entire frame, it wouldn't be beneficial to define a region that covers the ENTIRE frame!

I don't expect it wil save me a whole lot of time in 3D, but my compositor tells me it would save him a lot of time for any processor-intensive effects he applies to my CG elements (like blur, etc).

Please let me know if there is a method within maya to have the render region driven by the alpha channel.

Many thanks