Rendering Backgrounds

One of the things I've been experimenting lately is creating 3d mattes for background. One of the difficult things involved is matching the camera location and angle, and then lighting. Just imagine a room with matched lighting and angles (and even receive shadows from the subject) - and the best part is that you can change it within seconds.

The first step is having a background that reflects a similar light to the background you're planning to project. For me, I'll be rendering a room similar to an anechoic chamber. Since it'll be white, I'll just roll a white seamless under the model and create a path around him.

Then I fire up my favorite 3D program, and create a room large enough for the light to bounce around in a realistic manner (the other half of rendering I used environment HDRI). I made some boxes as reference to the model and object to cast the proper shadows.

After matching the camera location relative to the subject(s), I fire up the render. I also create a second render for the ambient occlusion (in other words, shadows).

I layer the images together, and add some blur to the AO render to give a little depth-of-field to match the camera's f/8 at a close distance.

It may not seem much for all this work, but my photojournalism professor always emphasized for us to be aware of the background.