Digital Artform

Here's an image of four spheres. It was rendered with a new camera (Camera 1) with all settings reset to their default values.

Here's a test slide prepared using the render from Camera 1. It's nothing fancy - just a simple Photoshop-generated negative of the image rendered by Camera 1.

I have created a second camera - Camera 2. I have assigned this camera reset, default settings. I'm going to project the test slide rendered by Camera 1 onto the geometry rendered by Camera 2.

Since the projecting camera (Camera 2) and the original rendering camera (Camera 1) have identical attributes, the image projected by Camera 2 should precisely fit onto the geometry rendered by Camera 1.

Here's the first render. You can see from the presence of the slide's white background on the spheres that there is a misalignment. This is a problem.

Here's my attempt to solve the problem by changing the "fit type" of the projection.

Finally we have a correct alignment of projected image and rendered image. Let's look at one more (better?) method of achieving this alignment...

This time, I've changed the gate of the projection.

This method also achieves a correct alignment, and may be the preferred method.

Oh, one last thing...

If you are using Slim and Renderman and you want to get accurate camera projection in Maya, look here.

UPDATE 12/11/05
Your best bet is to find the rendering camera at the frame you wish and simply duplicate it, rather than building a new camera from scratch and trying to match parameters.