After I posted my two latest bigger projects, Maison de Verre and Salle Labrouste, a few people asked how I obtained my DOF, and in particular the strangely shaped bokehs that came with it. The answer: custom aperture maps.
Custom apertures are not specific to CG. Photographers have played with stencils attached to their lenses for decades. Here is one I did last Christmas with a simple piece of perforated cardboard:
The same principle applies in V-Ray. In fact, it is a lot simpler to do it that way than in post. But to start with the basics, here is a rather boring render done with V-Ray’s default DOF settings (models from lincoln3dscans.co.uk)
We can do much better than that. And for a start, we don’t even need custom aperture maps. Just turn on the “bokeh” option in the V-Ray Physical Camera settings and play with the various options. Below are the settings I used for the following image:
That’s a lot more interesting. Not only can you define the shape of your aperture with a great deal of control, but you can also replicate the curvature of the lens, which warps the bokehs into a circular pattern across the image. You can see exactly what I mean in the following image. The key value here is an optical vignetting of -2.1 (which may be too much for a production image):
But for real, serious fun, turn on the “bitmap aperture” option and load a custom aperture map (the other options remain accessible except the “rotation” option). Note that if you do not untick the “affect exposure” option, maps that have a smaller aperture will make your bokehs smaller and your image render darker.
Here are a few examples of images done with custom maps, followed by the respective maps (note how the motif gets inverted when the blurred object is before the point of focus). Feel free to grab them and abuse them and let me know what you come up with. Better still, do your own and show me what you come up with.