[[Image:prop_txrx1_tn.png|thumb|400px|Transmitters and receivers adjusted above an uneven terrain surface.]]
[[Image:prop_txrx2_tn.png|thumb|400px|The associated base point sets with the adjusted transmitters and receivers on the terrain.]]
EM.Terrano uses '''Point''' objects to position transmitters and receiver in the propagation scene. Points are regular CAD objects that can be moved around (translated) in the project workspace.  , all are tied up with point objects in the project workspace.   The point objects that are used to represent the transmitters and receivers are grouped together and organized as '''Base Sets''' in the "Physical Structure" section of the navigation tree. When you move the point objects or change their coordinates, all of their associated transmitters or receivers immediately follow them to the new location. For example, you can define a grid of receivers using a base set that is made up of a uniformly spaced array of points and spread them in your scene. All of these receivers have the same height because their associated base points all have the same Z-coordinates. When your receivers are located above a flat terrain like the global ground, their Z-coordinates are equal to their height above the ground, as the terrain elevation is fixed and equal to zero everywhere. The same is true for transmitters, too.
In many propagation modeling problems, your transmitters and receivers may be located above an irregular terrain with varying elevation across the scene. In that case, you may want to place your transmitters or receivers at a certain height above the underlying ground. The Z-coordinate of a transmitter or receiver is now the sum of the terrain elevation at the base point and the specified height. EM.Terrano gives you the option to adjust the transmitter and receiver sets to the terrain elevation. This is done for individual transmitter sets and individual receiver sets. At the top of the Transmitter Dialog there is a check box labeled "'''Adjust Tx Sets to Terrain Elevation'''". Similarly, at the top of the Receiver Dialog there is a check box labeled "'''Adjust Rx Sets to Terrain Elevation'''". These boxes are unchecked by default. As a result, your transmitter sets or receiver sets coincide with their associated base points in the project workspace. If you check these boxes and place a transmitter set or a receiver set above an irregular terrain, the transmitters or receivers are elevated from the location of their associated base points by the amount of terrain elevation as can be seen in the figure below.