Urban Geometry Processing

This topic contains the following information about STK's processing of urban geometry data:

  • Advice for making the geometry processing time efficient; the time to initialize urban geometry (shapefile) in a scenario can vary greatly, from seconds to several hours
  • Insights into STK’s processing of urban geometry data
  • Additional insights to make sure processing proceeds properly

Preparing the urban geometry or shapefile data

Both the complexity and area of the shapefile contribute to the time it takes to initialize urban geometry. To reduce processing time, use a third-party GIS tool to do the following:

  • Crop the extents of the input shapefile to minimize the area used.
  • Consider breaking you analysis into sections and separate runs, if possible.
  • Simplify the geometry detail; simple rectangles are best.

For further insights on shapefiles, see Shapefile Requirements.

Triggering urban geometry processing

When does the urban geometry initialization begin? First, you must make sure that you selected the Use check box on the RF > Environment > Urban & Terrestrial page of the scenario properties. However, clicking Apply or OK in the Properties window does not trigger the calculations. You must also do one of the following for the first time.

  • Compute a single Access between a transmitter and receiver or from a Radar to a target when:

    • you compute access in the Access Tool (when Comm constraints are on any of the access objects)

    • you run a report that calls elements that include atmospheric loss elements like “Link Budget Detailed” or “Radar Environment”

  • Compute a chain Access where there are transmitter and receivers or Radar to target inside, similar to Access, when:

    • you right-click a Chain object, select Chain, and select Compute Accesses (when Comm constraints are on any of the objects in the Chain)

    • you run a report that calls elements that include atmospheric loss elements like “Digital Repeater” or “Bent Pipe”

  • Compute a Coverage Access using one of the following types of calculations:
    • When you right-click a CoverageDefinition object, select CoverageDefinition, and select Compute Accesses (when a child FOM is set to Access Constraint using any Comm or Radar constraint)

    • CommSystem Access when you click Compute from the right-click menu

    • Parallel Coverage doesn’t work with the Urban Propagation extension.

This urban geometry calculation happens up front one time and then STK saves it with the scenario. STK will only clear it if you apply a change to the RF > Environment > Urban & Terrestrial page of the scenario properties.

Processing time for urban geometry initialization

This section describes how to follow the urban geometry initialization processing in STK, according to these steps:

  1. STK displays a message in the Message Viewer that indicates when urban geometry initialization begins. To see all processing messages, click the View menu and select Message Viewer. In the Message Viewer listing area, right-click and select Clear All Tabs. At the bottom left of the Viewer, click the Infos tab.
  2. When urban geometry initialization begins, you will see the following messages appear in close succession.

    Urban Propagation Wireless InSite Model processing terrain facets, processing time depends time depends on the terrain resolution.

    Urban Propagation Wireless InSite Model terrain facet processing step is complete.

    Urban Propagation Wireless InSite Model initializing urban geometry information, processing time depends on urban geometry size.

  3. When urban geometry initialization completes you will see this message.

    Urban Propagation Wireless InSite Model urban geometry data initialization is complete.

Additional insights

If you are using terrain for the Building Height > Reference method, you must do the following:

  • Select the Use Terrain Data check box.
  • Have a single terrain source that encompasses the shapefile area loaded in the Scenario Properties.
  • Set your terrain resolution appropriately. The higher the resolution of the terrain file is, the longer the runtime will be.

When using Coverage or Comm System for static links, open the object’s Properties and go to the Basic > Interval page. Set the stop time to “+1sec”.