The following image will help the user identify how the program identifies with ceilings, walls, and groundplane (a cylinder represents the walls and discs represent the ceiling and ground plane).
The image shows a ceiling height and wall height of two different values. For example, a coil surrounded by 4 short walls within a larger building.
If you are operating a Tesla Coil in your garage, the wall, ceiling, and ground plane radius would have the same value (center of coil to nearest wall). The wall and ceiling heights would have the same value.