Keywords | File Formats

Interval List File Format (*.int)

An interval list file is an ASCII text file that is formatted for compatibility with STK and ends in a.int extension. Interval list files contain start and stop time pairs used to constrain an object or to indicate the times during which an object should display in the 2D Graphics window. Interval list files can be useful when you need to provide STK with data for a vehicle to model certain unique circumstances. Each start and stop time pair can define an optional string of data that contains the truncated path of an object.

STK allows you to import the data in any properly formatted interval file for use in a variety of areas. For instance, intervals list files can be used:

• 3D model pointing intervals
• 3D object to object lines display times
• Display times for 2D graphics
• Intervals for temporal constraints
• 2D graphics for vehicles using custom intervals
• 3D covariance contour graphics
• 3D text annotations (via Connect)
• 3D covariance contours (via Connect)
• Event Reporting

Keywords

Each interval list file, regardless of the type of interval data in the file, contains some common elements called keywords. In order for a interval list file to be formatted correctly, it must contain the following keywords. Keywords, and their associated values, must precede the specification of the actual data points.

Keywords used in interval files are NOT case-sensitive; the capitalization used in this document is for readability.

Keyword	Required	Description
stk.v.<major release number>.<minor release number>	Yes	The version of STK software for which the file is formatted to be used. Files can be created in, and imported to, STK software versions consistent with the file version stamp or higher. The version stamp must be the first line in the interval list file. Example: stk.v.4.0 A file created in and stamped with this version could be imported into STK software version 4.0 through the most recent version.
BEGIN IntervalList END IntervalList	Yes	Set off the beginning and end of the interval list keyword group. Refer to any of the sample files included in the File Format section for examples.
BEGIN Intervals END Intervals	Yes	Set off the beginning and end of the actual list of interval pairs. Refer to any of the sample files included in the File Format section for examples.

File Formats

An interval file can be in one of two formats: one in which all times are expressed in seconds past a specified epoch, using the ScenarioEpoch; and one in which all times are entered in the STK-supported date format specified, using the DateUnitAbrv.

Each line of data is an interval specification that contains a start time, a stop time and an optional data string. Whether or not the string is used depends on how the application is using the file. If the start and stop times are not numerical, they must be enclosed in quotes.

ScenarioEpoch

When you use the ScenarioEpoch format, the reference epoch time for the time values of the data in the file. Specify the scenario epoch using Gregorian UTC time (dd mmm yyyy hh:mm:ss.s). There is no relationship between the scenario epoch specified in the interval list file and the actual scenario epoch specified in the Time Period properties for the scenario.

To specify intervals pairs expressed in seconds past a specified epoch, you must first specify the epoch using the ScenarioEpoch keyword phrase. Then, specify interval pairs in seconds. An interval list file with all times expressed in seconds past a specified epoch might look like this sample file.

If the ScenarioEpoch is not specified, the interval pairs in the file will correspond to the actual scenario epoch. This may result in some incorrect times when using certain time formats.

DateUnitAbrv

When you use the DateUnitAbrv format, you also indicate the STK-supported date format in which interval pairs will be expressed by specifying the appropriate unit abbreviation. All date/time pairs are enclosed in quotes. For acceptable abbreviations, open the Units page of the Scenario's Basic properties by double-clicking the scenario in the Object Browser and selecting the Units page.

If you're specifying date pairs in anything other than seconds past a specified epoch, dates can't be local referenced; that is, local Gregorian (LCLG) and local Julian (LCLJ) date formats can't be used. In addition, the Mission Elapsed date format isn't available at this time.

An interval list file using the STK-supported UTC Gregorian date format might look like this sample file.

Optional Data String

The optional data string can be used to override default values for the target (or object) used for target times, the display times color, the pointing target, or a graphics attribute. Examples of optional data strings follow.

Invalid options in the data string will be ignored.

Target or Object Data String Example

Overrides the default target (or object) to be used for sensor targeted pointing times or vehicle attitude targeted pointing times.

stk.v.8.0 
BEGIN IntervalList
            DATEUNITABRV UTCG
BEGIN Intervals
            "1 Jul 2006 12:03:00.00" "1 Jul 2006 12:25:00.00" Facility/Philadelphia
            "1 Jul 2006 13:03:00.00" "1 Jul 2006 13:25:00.00" Facility/Sacramento
            "1 Jul 2006 14:08:00.00" "1 Jul 2006 14:29:00.00" Facility/Philadelphia
            "1 Jul 2006 15:08:00.00" "1 Jul 2006 15:39:00.00" Facility/Sacramento
END Intervals
END IntervalList

Color Data String Example

Overrides the default display time color for object lines in the 2D and 3D Graphics windows.

stk.v.10.0 
BEGIN IntervalList
            DATEUNITABRV UTCG
BEGIN Intervals
            "1 Jul 2007 12:03:00.00" "1 Jul 2007 12:25:00.00" Color red
            "1 Jul 2007 13:03:00.00" "1 Jul 2007 13:25:00.00" Color green
            "1 Jul 2007 14:08:00.00" "1 Jul 2007 14:29:00.00" color Orange
            "1 Jul 2007 15:08:00.00" "1 Jul 2007 15:39:00.00" color #0000ff
END Intervals
END IntervalList

Pointing Target Data String Example

Overrides the default model pointing target for the interval list.

stk.v.9.0
BEGIN IntervalList
DateUnitAbrv UTCG
BEGIN Intervals
    "1 Jul 2009 15:00:00.000000000" "1 Jul 2009 16:54:15.261618646" Sun
    "1 Jul 2009 16:56:15.079015486" "1 Jul 2009 18:32:21.721869287" Viewer
    "1 Jul 2009 20:44:05.326773339" "1 Jul 2009 22:52:47.112232494" 
    "2 Jul 2009 01:15:07.664755258" "2 Jul 2009 02:21:38.579066836" Sun
    "2 Jul 2009 11:21:47.041087041" "2 Jul 2009 12:00:00.000000000" Satellite/Sat315
END Intervals
END IntervalList

2D Graphics Attribute Data String Example

Overrides default graphic attributes for 2D Graphics attributes custom intervals.

stk.v.9.0
BEGIN IntervalList
DateUnitAbrv UTCG
BEGIN Intervals
    "1 Jul 2009 15:00:00.000000000" "1 Jul 2009 15:54:15.261618646" Show On Color red LineStyle dotted
    "1 Jul 2009 16:12:15.079015486" "1 Jul 2009 18:32:21.721869287" 
    "1 Jul 2009 19:00:05.326773339" "1 Jul 2009 19:52:47.112232494" Show On Color green Linewidth 3
    "1 Jul 2009 21:15:07.664755258" "1 Jul 2009 22:21:38.579066836" MarkerStyle Plus
    "1 Jul 2009 22:41:47.041087041" "1 Jul 2009 23:00:00.000000000" Color #ed8e02 LineStyle dashed
 
END Intervals
END IntervalList

3D Graphics Attribute Data String Example

Overrides default graphic attributes for 3D Graphics covariance intervals, and 3D Graphics contours covariance pointing intervals. Valid options are: Show, Color, LineWidth, and Translucency.

stk.v.9.0
BEGIN IntervalList
DateUnitAbrv UTCG
BEGIN Intervals
    "1 Jul 2009 15:00:00.000000000" "1 Jul 2009 15:54:15.261618646" Show On Color red 
    "1 Jul 2009 16:12:15.079015486" "1 Jul 2009 18:32:21.721869287" 
    "1 Jul 2009 19:00:05.326773339" "1 Jul 2009 19:52:47.112232494" Linewidth 3
    "1 Jul 2009 22:41:47.041087041" "1 Jul 2009 23:00:00.000000000" Color #ed8e02 translucency 50
 
END Intervals
END IntervalList