As previously discussed, a benefit of exporting a range of frames is that you can later tweak Lumion's output and perform color correction and other adjustments. To make your life easier, Lumion allows you to export along with a range of frames some render passes, as shown in the following screenshot:
The Custom output is where you can find all the render passes available. Each letter corresponds to a render pass that is explained in the following list:
Depthmap (D): This is a grayscale map with information regarding the distance of the 3D models from the camera.
Normalmap (N): This is similar to the one used to create bumps in the materials, but this render pass doesn't have many useful applications.
SpecularReflection map (S): This render pass stores information regarding the surface highlights and reflections.
Lighting map (L): This render pass stores light and brightness information for each surface in the scene.