=== Discretizing the Scene ===
In a typical SBR simulation, a ray is traced from the location of the source until it hits a scatterer. The [[SBR Method|SBR method]] assumes that the ray hits either a flat facet of the scatterer or one of its edges. In the case of If hitting a flat facet, the specular point is used to launch new reflected and transmitted rays. The surface of the facet is treated as an infinite dielectric medium interface, at which the reflection and transmission coefficients are calculated. In the case of If hitting an edge, a large number of new diffracted rays are generated in the scene. However, only those who reach a nearby receiver in their line of sight are ever taken into account. In other words, diffractions are treated locally.
[[EM.Cube]]'s [[Propagation ModuleTerrano]] allows you to draw any type of surface or solid CAD objects under impenetrable and penetrable surface groupsor penetrable volumes. Some of these objects have flat faces such as boxes, pyramids, rectangle or triangle strips, etc. Some others contain curved surfaces or curved boundaries such as cylinders, cones, etc. All the non-flat surfaces have to be discretized in the form of a collection of smaller flat facets. [[EM.CubeTerrano]] uses a triangular surface mesh generator to discretize the penetrable and impenetrable [[Surface Objects|non-flat surface objects]] of your propagation scene. This mesh generator is very similar to the ones used in Unlike [[EM.Cube]]'s two other computational modules: MoM3D and Physical Optics (PO), 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.
You can build a variety of surface and [[Solid Objects{{Note|solid Discretizing smooth objects]] using [[EM.Cube]]'s native "Curve" CAD objects like lines, polylines, circles, etc. You can use tools like Extrude, Loft, Strip-Sweep, Pipe-Sweep, etc. a triangular surface mesh gives rise to transform curves into surface or [[Solid Objects|solid objects]]. '''However, keep in mind a large number of small edges among the facets that all the "Curve" CAD objects are ignored by the SBR simply mesh generator artifacts and are therefore should not sent to the simulation enginebe considered as diffracting edges}}.'''
=== Viewing & Modifying the SBR Mesh ===
You can view and examine the discretized version of your scene objects as they are sent to the SBR simulation engine. To view the mesh, click the '''Mesh''' [[File:mesh_tool.png]] button of the Simulate Toolbar or select '''Simulate > Discretization > Show Mesh''', or use the keyboard shortcut '''Ctrl+M'''. A triangular surface mesh of your physical structure appears in the project workspace. In this case, [[EM.Cube]] enters it mesh view mode. You can perform view operations like rotate view, pan, zoom, etc. But you cannot select objects, or move them or edit their properties. To get out of the Mesh View and return to [[EM.Cube]]'s Normal View, press the '''Esc Key''' of the keyboard, or click the Mesh button of the Simulate Toolbar once again, or go to the Simulate Menu and deselect the '''Discretization >''' '''Show Mesh''' item.
=== SBR Simulation Types ===
[[EM.Cube]]'s [[Propagation Module]] Terrano offers three types of ray tracing simulations:
* Single-Frequency Analysis
* Frequency Sweep
* Parametric Sweep
An A single-frequency SBR analysis is the simplest ray tracing simulation and involves the following steps:
# Set the unit of project scene and the frequency of operation. Note that [[EM.Cube]]'s default project unit is millimeter. When working with the [[Propagation Module]], pay attention to the project unit. Radio propagation problems usually require meter, mile or kilometer as the project unit.