Nuke, Light Passes and 3D - Dynamic Composites
I art direct magazines and often make little 3D-rendered images for the content. Some are 3D illustrations and some are simply faked photos. This is good for those times when hiring a product photographer is overkill. Some magazines have little white rooms for shooting stuff like this but I don't and I find the quality is lacking if you don't have good studio lighting equipment. Enter the 3D renderer...
This is the nice thing about having skills in 3D to complement your design/art direction – you don't have to rely on others (or worse, stock images) for all your imagery. Sure, people look at me like I'm on crack when I say I use the high-end 3D compositor Nuke for print work but, for dynamic template content which you don't want to re-render, it makes a lot of sense. The benefits of having your separated lights in a floating-point compositor become obvious when you see this:
This gives you a lot of flexibility to control product photography CGI, where lighting plays the major role in making it all sleek-looking. Since all light in 32-bit EXRs is stored as floating-point, there is no danger of degrading the quality with such drastic changes. It's the ultimate RAW file that photographers would kill for.
If you haven't figured out what's going on in the video above, the technique is simple: You render each light with the target objects on a separate render layer and in your compositor, add the resulting EXR images (or any other format that is floating point). In Nuke "Add" is a Merge node in "Plus"mode and in After Effects, it's "Linear Dodge" (Screen mode is similar but clamps the white to prevent clipping).
My latest foray into using these light passes goes further to make the decals completely dynamic so I can just change the image and the whole scene updates with the new art. I'm also using Maxwell for this project. Now, Maxwell isn't the most render-pass friendly renderer (you have to render diffuse and reflection passes as two different renders) but it has a very easy system for outputting lights as separate floating point images (it's called Multilight). Mental Ray for Maya users also have this sweet script called Felix that does something similar. With V-Ray, you have to use Render Layers in Maya, which is a nuisance.
This gets really good when you use Nuke's 3D geometry with these light passes. Export your camera data from Maya with the pass2nuke.mel script (or import an FBX camera into Nuke), import your meshes with UVs and composite the rendered images for a high-quality and dynamic rendering:
Render out a frame and place in your layout:
Next issue, wash, rinse and repeat from another angle. If I wanted to fake the way the ink affects the glossiness, I could easily use the luminance of the rendered image map and have it adjust the reflective pass to create the illusion of glossy ink on a matte page.
Now, that is not a very physically accurate approach (I'm sure Next Limit's people would cry seeing how I used Maxwell here) and in reality there would be some minor colour bleeding that should happen where the pages meet near the spine but it's an easy thing to fake it by painting in a little faux colour bleed in Photoshop. Luckily, most of the magazine pages that I would place in this template are mostly white around the trim so it works out well.