| style="width:200px;" | Ray reflection, ray diffraction, ray transmission in free space
| style="width:250px;" | All solid & surface geometric objects, no curve objects
| style="width:300px;" | Behaves similar to impenetrable surface and uses thin wall approximation for generating transmitted rays, used to model hollow buildings with ray penetration, entry and exit
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| style="width:30px;" | [[File:terrain_group_icon.png]]