Point Files

You can use a point file (.pnt) to define the exact location of grid points to be used for coverage calculations. These points can be specified using geodetic latitude and longitude or geodetic latitude, longitude and altitude values. If altitude is omitted then the Altitude value and Altitude reference surface specified in the coverage definition's Basic properties is used. You may also explicitly override the altitude provided in the file using the option provided in the coverage definition's Basic properties. Finally, if altitude is included and the grid instance is defined as a target or facility using Terrain data, altitude from the point list is overridden.

Inside the PointList are several keywords that identify the point. Each point file contains some common elements:

Keywords used in every point file

Keywords Description
STK version number The version of STK software for which the file is formatted to be used.
AltitudeMethod

Specifies the altitude reference when the pointList contains altitude values.

Valid values are: Altitude, Radius, AltAboveTerrain, AltAboveMSL, and Depth.

If no valid value is specified or the keyword is missing, then the setting will be Altitude, which indicates that the values are measured with respect to the central body ellipsoid surface.

Note that for the altitude values in the files to be used, the custom point altitude method on the coverage definition's Basic properties must be set to Use File Values.

Specify Altitude in Meters
BEGIN PointList
END PointList keywords		 Set off the beginning and end of the PointList keyword group.

The structure of a generic Point List file, then, looks something like that shown here:

Generic point list file structure

stk.v.4.2.1

Begin PointList

.

.

.

End PointList

The point list file contains a list of latitude, longitude pairs or latitude, longitude, altitude values. To include values, enclose the data in a BEGIN PointList and END PointList keyword phrase, which should include the following keywords and data points:

<Latitude> <Longitude> pairs - Perimeter points that define an area entered in degrees. <Altitude> may also be included as the third parameter.

A sample Point List file format is provided for your reference.

Sample Point List file format

stk.v.4.2.1

#
# This is a sample point list file
# Use with a Latitude Bounds Region (-45.0 to +45.0)
# Use an Equidistant Cylindrical projection centered on 75 deg Longitude
#

Begin PointList

3.9346423789e+01 -6.0260748372e+01 0.0000000000e+00
3.9613371741e+01 -6.6285429903e+01 0.0000000000e+00
3.9880319688e+01 -7.3881767479e+01 0.0000000000e+00
3.9613371741e+01 -8.1478105061e+01 0.0000000000e+00
3.9613371741e+01 -8.9336385316e+01 0.0000000000e+00
3.9880319688e+01 -9.5361066842e+01 0.0000000000e+00
4.0147267640e+01 -9.9814092322e+01 0.0000000000e+00
3.5609152502e+01 -9.9814092322e+01 0.0000000000e+00
3.0804089417e+01 -1.0007603499e+02 0.0000000000e+00
2.4397338635e+01 -9.9814092322e+01 0.0000000000e+00
2.0126171449e+01 -1.0007603499e+02 0.0000000000e+00
1.6121952209e+01 -9.9814092322e+01 0.0000000000e+00
1.1049941172e+01 -9.9814092322e+01 0.0000000000e+00
5.7109821878e+00 -1.0007603499e+02 0.0000000000e+00
-4.2882064180e-01 -1.0007603499e+02 0.0000000000e+00
-4.2882064180e-01 -9.3789410791e+01 0.0000000000e+00
-4.2882064180e-01 -8.8288614612e+01 0.0000000000e+00
-4.2882064180e-01 -8.1740047734e+01 0.0000000000e+00
-4.2882064180e-01 -7.6501194229e+01 0.0000000000e+00
.
.
.
2.8853503184e+01 -1.4037499983e+02 0.0000000000e+00
3.4968152869e+01 -1.3999999983e+02 0.0000000000e+00
3.9554140126e+01 -1.3999999983e+02 0.0000000000e+00
4.0318471337e+01 -1.3699999985e+02 0.0000000000e+00
3.9936305732e+01 -1.3174999988e+02 0.0000000000e+00
3.9936305732e+01 -1.2762499990e+02 0.0000000000e+00
3.9936305732e+01 -1.2274999993e+02 0.0000000000e+00
4.0318471337e+01 -1.1899999995e+02 0.0000000000e+00
3.9554140126e+01 -1.1299999999e+02 0.0000000000e+00
-4.0700636942e+01 -1.1224999998e+02 0.0000000000e+00

End PointList