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Accounting for Bleed When Rendering for Print

I do most of my 3D work for stills and print in magazines so I need to often account for the bleed and trim factors. For those unfamiliar with these print terms, a bleed is the area outside the page margins that are cropped out when printing (this crop is the trim dimension). When you do illustration that going to go to the edge of the page, you must also add the bleed to the edges that crop or else you will get hairlines of white when the pages invariably shift on press. Most magazine bleeds are 0.125” on all outside edges (unless they are on a really bad press, in which case it might be 0.25”). For metric folks, 0.125” is 3.175 millimetres.

When working in Maya, I often use the image plane as a visual block for my bleed area since looking at an image without the crop is misleading. You’ll often find you have the perfect image but then once it’s cropped for the bleed, it looks terrible. Sometimes, it’s easy to use the clone tool in Photoshop (or the amazing content-aware fill tool) to extend the border but I’m going to be dealing with complex halftone effects that aren’t going to clone easily. So, in these cases, I make a masked RGB image that blocks out the area that’s reserved for bleed. That way, all my renders and my viewport show me the scene “as trimmed.”) The workflow is easy: find out your illustration dimensions, add the bleed to the relevant edges and then make an alpha channel with the bleed masked in white. Import the image as the camera’s Environment Image Plane and you’re set.

Once you are confident with the composition and want the final image with bleed, just remove the Image Plane and render the final. The only drawback to this approach (other than having your Image Plane occupied), is that you are effectively looking at everything through an alpha mapped image, which might slow your scene drawing down while working. So I suggest only using it when you need to plan composition or for pre-final renderings (and make the image as low resolution as possible to save texture memory). There’s an easy way to toggle the plane only during render times, by adding a pre- and post-render MEL command:

Pre (show it):

setAttr imagePlane1.displayMode 3;

Post (hide it again):

setAttr imagePlane1.displayMode 0;

Update: Just got an email from Michele De Pascalis who had a tip for using the Connection Editor or Node Editor to hook up multiple image planes to one camera. This really helps solve teh only major issue with this image plane bleed workflow. Thanks, Michele.

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