{| class="wikitable"
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| style="width:150px;" ! scope="col"| Block Type| style="width:250px;" ! scope="col"| Ray Interaction Type| style="width:250px;" ! scope="col"| Object Types Allowed
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| style="width:150px;" | '''[[Glossary of EM.Cube's Materials & Physical Object Types#Impenetrable Surface | Impenetrable Surface]]'''| style="width:250px;" | Ray reflection, ray diffraction| style="width:250px;" | All solid & surface geometric objects, no curve objects
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| style="width:150px;" | '''[[Glossary of EM.Cube's Materials & Physical Object Types#Penetrable Surface | Penetrable Surface]]'''| style="width:250px;" | Ray reflection, ray diffraction, ray transmission through thin walls| style="width:250px;" | All solid & surface geometric objects, no curve objects
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| style="width:150px;" | '''[[Glossary of EM.Cube's Materials & Physical Object Types#Terrain Surface | Terrain Surface]]'''| style="width:250px;" | Ray reflection, ray diffraction| style="width:250px;" | All surface geometric objects, no solid or curve objects
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| style="width:150px;" | '''[[Glossary of EM.Cube's Materials & Physical Object Types#Penetrable Volume | Penetrable Volume]]'''| style="width:250px;" | Ray reflection, ray diffraction, ray transmission in material media| style="width:250px;" | All solid geometric objects, no surface or curve objects
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| style="width:150px;" | '''[[Glossary of EM.Cube's Materials & Physical Object Types#Base Location Set | Base Location Set]]'''| style="width:250px;" | Either ray generation or ray reception| style="width:250px;" | Only point objects
|}
* They represent a specular interface between two media of different material compositions for calculating the reflection, transmission or diffraction coefficients.
An outdoor propagation scene typically involves several buildings modeled by impenetrable surfaces. Rays hit the facets of impenetrable buildings and bounce back, but they do not penetrate the object. It is assumed that the interior of such buildings are highly dissipative due to wave absorption or diffusion. An indoor propagation scene typically involves several walls, a ceiling and a floor arranged according to a certain building layout. Penetrable surfaces are used to model the exterior and interior walls of buildings. Rays reflect off these surfaces and diffract off their edges. They also penetrate the thin surface and continue their path in the free space on the other side of the wall. Terrain surfaces with irregular shapes or possibly random rough surfaces are used as an alternative to the flat global ground. You can also build mixed scenes involving both impenetrable and penetrable blocks or irregular terrain. In the context of a propagation scene, penetrable volumes are often used to model block of rain, fog or vegetation. Base location sets are used to geometrically represent point transmitters and point receivers in the project workspace.
=== Organizing the Propagation Scene by Block Groups ===