Changes

=== Discretizing Why Do You Need to Discretize the Scene ? ===

In a typical EM.Terrano's SBR simulation, a ray is traced from tracer uses a method known as Geometrical Optics (GO) in conjunction with the location Uniform Theory of Diffraction (UTD) to traces the rays from their originating point at the source until it hits a scattererto the individual receiver locations. The [[Ray may hit obstructing objects on their way and get reflected, diffracted or transmitted. EM.Terrano's SBR Method|SBR method]] solver can only handle diffraction off linear edges and reflection from and transmission through planar material interfaces. The underlying theory for calculation of reflection, transmission and diffraction coefficients indeed assumes that the material media of infinite extents. When a ray hits either a flat facet of specular point on the scatterer or one surface of its edges. If hitting a flat facet, the specular point is used to launch new reflected and transmitted rays. If hitting an edgeobstructing object, a large number of new diffracted rays are generated in local planar surface assumption is made at the scenespecular point.

[[EMImage:MORE.Terranopng|40px]] allows you Click here to draw any type of surface or solid CAD objects under impenetrable and penetrable surface groups or penetrable volumes. Some of these objects have flat faces such as boxes, pyramids, etc. Some others contain curved surfaces or curved boundaries such as cylinders, cones, etc. All the non-flat surfaces have to be discretized in learn more about the form theory of a collection of smaller flat facets. '''[[EM.Terrano]] uses a triangular surface mesh generator to discretize the non-flat surface. Unlike [[EM.CubeSBR Method]]'s other computational modules, EM.Terrano's surface mesh does not depend on the operating wavelength. Its sole purpose is to discretize curved scatterers into a flat facets. Therefore, geometrical fidelity is the only criterion for the quality of a SBR mesh'.

{{Note|Discretizing 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 gives rise to 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.