Facility Properties | Place Properties | Target Properties
Define an Azimuth-Elevation Mask
The AzElMask properties, which are a part of the Basic properties for facilities, places and targets, enable you to define an azimuth-elevation mask for a facility, place, or target. Use the AzElMask page of the object's 2D Graphics properties to display the azimuth-elevation mask in the 2D Graphics window.
Begin by selecting the method for supplying mask data.
| Use | Description |
|---|---|
| None | No azimuth-elevation mask will be defined. |
| Terrain Data | Use the Terrain data specified on the Terrain page of the scenario's Basic properties to define an azimuth-elevation mask.
Terrain is sampled along a set of azimuth rays up to the distance set by the maximum range to consider, to determine the maximum elevation profile along the azimuth from the reference location of the facility, target, or place. The terrain data files available in this scenario for visualization and analysis are listed on the Terrain properties page. |
| Mask File | Use the data in an external azimuth-elevation mask file (*.aem). Azimuth-elevation mask files must be formatted to work with STK and end in a .aem extension. If you select the Mask File option, specify the file containing the azimuth-elevation mask to be displayed, or use the  button to browse for a file. |
Terrain data does not typically include structures such as buildings.
The time to compute the AzEl Mask from terrain data depends on the following:
- the resolution of the terrain (higher resolution terrain is sampled more often)
- the maximum range considered when computing the mask (longer distances require more samples)
When computing the AzEl Mask from terrain, terrain blockage is only modeled up to the ground distance specified by the maximum range that was considered when generating the mask. If the AzEl Mask constraint is used when doing acces to an object, and the ground distance to the object is larger than the maximum range that was considered when computing the mask, then the mask may fail to correctly model the terrain blockage.
For example, a mask computed at 20 km maximum range may correctly model terrain blockage within a valley but fail to model blockage by the surrounding mountains location farther away: in that case, set the maximum range larger to correctly model the terrain. Note that for Earth, away from its tallest mountains, a maximum range of 160 km generally works well to account for terrain all the way to the horizon, though there are many locations where a much smaller range can provide accurate terrain blockage out to the horizon.
Save mask data in binary
Select this option to save the AzElMask data in binary. Saving the data in binary will generate a smaller file and reduce save and load time.
This option is only enabled when using terrain data for computing the AzElMask.
Use Mask for Access Constraint
Select this option to enable the Az-El Mask constraint on the Constraints->Basic properties page. You can use this option only if an azimuth-elevation mask is defined.