Changes

If your propagation scene contains only cubic buildings on the flat global ground, the assumptions of linear edges and planar facets hold well although they violate the infinite extents assumption. In many practical scenarios, however, your buildings may have curved surface or the terrain may be irregular. EM.Terrano allows you to draw any type of surface or solid CAD objects under impenetrable and penetrable surface groups or penetrable volumes. Some of these objects contain curved surfaces or curved boundaries and edges such as cylinders, cones, etc. In order to address all such cases in the most general context, EM.Terrano always uses a triangular surface mesh of all the objects in your propagation scene. Even rectangular facets of cubic buildings are meshed using triangular cells. This is done to be able to properly discretize composite buildings made of conjoined cubic objects.

Unlike [[EM.Cube]]'s other computational modules, the density or resolution of EM.Terrano's surface mesh does not depend on the operating frequency and is not expressed in terms of the wavelength. Its sole purpose is to discretize curved and irregular scatterers into flat facets and linear edges. Therefore, geometrical fidelity is the only criterion for the quality of an SBR mesh. It is important to note that discretizing smooth objects using a triangular surface mesh typically creates a large number of small edges among the facets that are simply mesh artifacts and should not be considered as diffracting edges. For example, each rectangular face of a cubic building is subdivided into four triangles along the two diagonals. The four internal edges lying inside the face are obviously not diffracting edges. A lot of subtleties like these must be taken into account by the SBR solver to run accurate and computationally efficient simulations.