Input | Constraints | Advanced Options | Output
Deck Access Tool
The Deck Access tool enables you to compute access to a set of objects, not currently defined within the STK scenario, from a single object within the scenario. Deck access operations are useful when you have a large number of objects that no longer need to be in the STK scenario but for which you would like visibility information. Using deck access can greatly reduce load and save time for such scenarios and minimize graphical clutter.
You can supply the definitions of the objects outside of the scenario via an external target deck file or from a star collection. The format of the file is defined by the class of object and the file extension. For example, you could use the deck access tool to compute access to a set of satellites, defined by two line element sets contained in a file, from a facility in the STK scenario. Star collections are defined by specifying a set of constraints on the contents of a star catalog. If an appropriate star collection is not available, click to create a new collection with the desired set of constraints and star catalog.
To open the Deck Access tool, select Deck Access... from the Analysis menu.
Input
Use the Input options to define the access computation task.
| Option | Description |
|---|---|
| Interval/Start Time and Stop Time | Indicate the time period over which STK will compute the access opportunities. For more information on the options available for time intervals and start and stop times, see Time Options. |
| Type | Indicate the type of object that is defined by the data in the specified file. |
| File | This appears when you select an STK object class as the type. Specify the file containing the target deck file, or use the  button to browse for a file.The appropriate file extension will be the default file type in the file
selection window. |
| Name | Displayed when you select a star collection as the type. Specify the star collection for STK to use as the source of star object information. Click to create a new star collection or to view/modify the configuration of existing star collections. |
All objects must be of the same type during a single deck access run.
The file extension is important to the deck access process since STK uses it to define the format of the data in the file. The file extensions and formats for each type are given below.
File extensions and formats
| Type | Extension | Format Description |
|---|---|---|
| Satellite | .tce/.tle/.omm/.xml/csv | Files containing GP data used with SGP4. |
| Facility/Place/Target | .lla | Files contain lines of the following format: [Name] Latitude Longitude [Altitude],
where Latitude and Longitude are given in degrees and Altitude is given in
meters. If you specify [Name], then you must also specify Altitude. [Name] must have at least one nonnumeric character (see warning below). If you don't specify [Name], then the target deck objects are identified as Point_NUM, where NUM is an index of unnamed definitions in the file. |
| Star | .str | Files contain lines of the following format: [Name] Right_Ascension Declination [Parallax] [RA_Proper_Motion Dec_Proper_Motion [Epoch]], where Right_Ascension and Declination are given in degrees, Parallax is given in arcseconds, proper motion is given in arcseconds/year, and the Epoch is specified in Julian Ephemeris Date. If you don't provide proper motion, then you may provide the Epoch. If you provide proper motion and omit the Epoch, the Epoch is set to J2000. [Name] must have at least one nonnumeric character (see warning below). If you omit [Name], then the target deck objects are identified as Star_NUM, where NUM is an index of unnamed definitions in the file. |
| Star Collection | n/a | n/a |
| Collection Subset | n/a | n/a |
| Area Target | .shp | This is the GIS shapefile containing polygon information. Target deck objects are identified via the NAME field of the shapefile entries if it exists. Otherwise, the target deck objects are identified as AreaTarget_NUM, where NUM is an index of unnamed definitions in the file. |
Star and Facility/Place/Target files cannot have [Name] values that are strictly numeric. STK attempts to read values that you must specify numerically in order. Since [Name] is an optional parameter, if an object [Name] is strictly numeric, STK will assume that you have omitted the [Name] and that the first number is the first required value (Right_Ascension for a star, or Latitude for facility/place/target).
For example, if you created a star file containing the following information:
123 1.23124 2.234124
STK would read it as:
| [Name] | No value specified |
|---|---|
| Right_Ascension | 123 |
| Declination | 1.23124 |
| [Parallax] | 2.234124 |
| [RA_Proper_Motion DEC_Proper_Motion] | No value specified |
| [Epoch] | No value specified |
In this example, the name of the star is supposed to be "123", and the file should have been read as:
| [Name] | 123 |
|---|---|
| Right_Ascension | 1.23124 |
| Declination | 2.234124 |
| [Parallax] | No value specified |
| [RA_Proper_Motion DEC_Proper_Motion] | No value specified |
| [Epoch] | No value specified |
To prevent this from happening, be sure you use names that contain at least one nonnumeric character. For example, if you created a star file containing the same information, but you added an alphabetic character to the name, like so:
123b 1.23124 2.234124
STK would read it as:
| [Name] | 123b |
|---|---|
| Right_Ascension | 1.23124 |
| Declination | 2.234124 |
| [Parallax] | No value specified |
| [RA_Proper_Motion DEC_Proper_Motion] | No value specified |
| [Epoch] | No value specified |
which would be accurate.
Altitude definition
This defines how STK uses and interprets altitude information from the selected input file for a Facility, Place or Target:
- AboveEllipsoid results in STK interpreting altitude values from the file as geodetic altitude above the reference shape of the scenario central body (WGS-84 ellipsoid for the Earth). If you do not specify altitude in the file, STK sets it to zero.
- OnTerrain results in STK overwriting the altitude values from the file with the terrain altitude at each specified geodetic location.
If you specify a constraint source that uses a terrain-based Az/El mask to constrain visibility, you should use the OnTerrain option to avoid the possibility of the specified altitude being below the surface of the local terrain. Under such a circumstance, the generated Az/El mask will not provide an accurate representation of visibility from the input location.
Constraints
If you select the Specify Constraint Source check box, you can select an instance of the target deck class (set using the Select Target Deck class option) from which STK will copy a set of access constraints. STK will associate this set of constraints with the target deck objects and use it in the deck access computations.
Advanced options
Click Advanced... to use a TLE Epoch Filter and to add target satellites that are found to have access to the primary object as new objects to the STK scenario.
Output
To generate deck access results, click . STK may present the results in a report window or write them directly to file. In any case, the format is defined by the DeckAccess report style associated with the object from which the Deck Access tool was launched.
Select the Compute in Parallel check box to use the STK Parallel Cluster when computing deck access. This extension enables STK to utilize additional processing resources to accelerate deck access computations. Using task-based parallelism, this extension groups large calculations into sets, simultaneously executing the sets on separate CPU cores, and reassembling the results for presentation and analysis.
Use the Sort and Output options here to define the presentation of deck access results.
Sort options
| Option | Description |
|---|---|
| By Object | Reported access intervals will be sorted first by object and then by start time. |
| By Start Time | Reported access intervals will be sorted first by start time. |
Output options
| Option | Description |
|---|---|
| Create Report | STK will present the results of the deck access in a report window. |
| Create File | STK will write the results of the deck access directly to a file. It is often desirable to write the results of a deck access run directly to a file since the number of access intervals can be very large. |