Spheric Zone

Another measure for the acceleration of the pre-processing and the prediction as well as for the reduction of the size of the pre-processed file is the introduction of a so-called Spheric Zone. Only visibility relations between such elements are investigated, that are within a certain maximum distance. All other (possible) visibility relations are ignored.
Figure 1. Spheric zone in an urban area.

Appropriate values are in the range of 400 – 800 meters for urban scenarios and 20 – 100 meters in indoor scenarios. If the value is chosen too small, the prediction accuracy decreases, because not all relevant visibility relations are then determined. Also, depending on the size of the buildings and their distance to each other, parts of the prediction area might not be reached anymore by the IRT model, because no visibility relations exist for that area.

Note: The functionality in an indoor scenarios is analogous.

To activate the spheric zone, the parameter Spheric Radius must be set to the according to value (in meters) when creating a prediction project.