Creating Lights That Match the Footage
Knowing how lights and shadows work in the real world, you can start creating lights in your 3D scene. Again, even the light settings are slightly different between the two render engines, but the illumination you have to achieve is similar, so let’s go through the list of things you’ll need to light this scene:
1. Of course, to see how the shadows will appear on the ground, you’ll need to create a plane for the floor to receive those shadows. For now, just create a plane and adjust its size so that it fits the area where the character is walking and is wide enough to receive Jim’s shadows.
2. Next, you’ll need a directional sun light that mimics the direction of the main light source for the original scene. Just press Shift + A and create a Sun Lamp. Align it by taking into account in what direction the shadows would be projected depending on the location of the light source.
3. Adjust the softness of the shadow to fit that from the footage. In Cycles, adjust the Size value on the Lamp tab of the Properties Editor. In Blender Render, enable Raytrace shadows and increase the samples, and adjust the Soft Size setting, which is also on the Lamp tab.
Tip
You can divide your screen to have a rendered preview of it on one side and the footage in the Movie Clip Editor on the other. This will allow you to compare both views and have a reference for how to move the lights until their shadows fit those in the footage.
4. Now, to prevent the areas in shadow from being completely black, add an environmental light. You could make it bluish, but because the whole scene looks slightly blue, keep it neutral (white) and later you’ll have more control in the compositor to tint it with blue and integrate it better.
In Cycles, go to the World tab in the Properties Editor and adjust the strength (enable Nodes if they are still disabled). Keep in mind this adjustment has to be very subtle and don’t worry for now if it doesn’t completely match the colors in the real footage, as you’ll fine-tune everything later in the node compositor.
In Blender Render, on the World tab, enable Environment Lighting and use a small value in the Energy parameter (about 0.35 or so), just to prevent the areas in the shadow from being absolutely black. If you want to use another color, change the Environment Lighting from White to Sky Color and, in the World panel, change the Horizon Color to a light blue.
Note
At this point, lighting your scene is pretty much guess work, as you have to test and adjust by eye the light intensity, color, and direction until they match the real footage. But don’t worry if you don’t light it perfectly on the first try; later, when you’re in the compositor, you’ll see much more clearly if your lighting fits the lighting from the real footage and, if it doesn’t, you can always adjust it and render again until it works nicely. Remember that making something cool is not a one-shot process; at certain points, you need to go back and try again to get a result you like.