[[Image:PROP4.png|thumb|400px|EM.Terrano's Global Ground Settings dialog.]]
=== Understanding the Computational Domain & Global Ground ===
The SBR simulation engine requires a finite computational domain. All the stray rays that emanate from a source inside this finite domain and hit its boundaries are terminated during the simulation process. Such rays exit the computational domain and travel to the infinity, with no chance of ever reaching any receiver in the scene. When you define a propagation scene with various elements like buildings, walls, terrain, etc., a dynamic domain is automatically established and displayed as a green wireframe box that surrounds the entire scene. Every time you create a new object, the domain box is automatically adjusted and extended to enclose all the objects in the scene.