target_ownship_distance: Target to ownship range

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Target to ownship range

Description

NOTE: This function is called automatically by create_scenario(). If you're using this, you likely want create_scenario() as it runs not only this function but also creates a scenario that can be used in most other functions in this package. If you're thinking of using this, check out create_scenario() first and make sure that you really want this function.

This function is a simplified version of target_track_distance() that calculates only the truth ranges and bearings of each target during the test. It may be important when trying to compare the sensor results to the truth data. For example, if one target was never detected by the sensor system then the results of target_track_distance() and target_assignment() would give no information about how close it came to ownship during the test because those functions deal primarily with the output of the sensor system. target_ownship_distance() will calculate find this information which can be combined with other outputs to get a more complete picture of the test and how the sensor system compared to this.

This functions works similarly to target_track_distance. The lon, lat, and alt of each target is interpolated to the time of ownship position measurements using a spheroidal Earth (WGS84). Nautilus uses the function interp_ellipse() to interpolate these positions. To avoid discontinuities (i.e., the jump from 359 degrees to 0), target headings are interpolated by first converting to sin and cos.

The target ranges are calculated using the straight-line distance by converting lon/lat/alt of the target and ownship to cartesian coordinates and then taking the square root of the sum of the squares.

This function can be used as a stand alone function or in conjunction with analysis functions to get the truth ranges and bearings of each target during the test.

Usage

target_ownship_distance(truthData, ownShipData)

Arguments

truthData

truthData: data frame containing all of the truth data for each target (likely from GPS or land-based radar systems). MUST have the following columns: time: (double) time of measurement. We currently recommend POSIX lon: (double) longitude of target at time of measurement lat: (double) latitude of target at time of measurement alt: (double) altitude of target at time of measurement truthID: (factor) name or identifier for target. We recommend letters or names heading: (double) target heading in degrees azimuth

ownShipData

data frame containing all of the truth position of the sensor system (likely from GPS or land-based radar systems). This may be ownship if testing something on a ship or the lat/lon position of a stationary ststem. MUST have the following columns: time: (double) time of measurement. We currently recommend POSIX lon: (double) longitude of target at time of measurement lat: (double) latitude of target at time of measurement alt: (double) altitude of target at time of measurement truthID: (factor) name or identifier for target. We recommend letters or names heading: (double) sensor system heading in degrees azimuth

Value

A dataframe containing the ranges and bearings from the sensor system to every target at each time the position of the sensor system was measured. The output columns are a limited version of target_track_distance() and includes:

• time: time of the measurement of ownship position

• ownShipTruthID: unique identifier for the reference platform

• ownShipLon: longitude of ownship at this time

• ownShipLat: latitude of ownship at this time

• ownShipAlt: altitude of ownship at this time

• slantRange: range from ownship to the target (straight-line distance)

• groundRange: range from ownship to the target (everyone's altitude is zeroed out)

• targetAspect: the target aspect (as seen from ownship) at this time

• trueBearingToTarget: true bearing (azimuth) to the target at this time

• relBearingToTarget: relative bearing (azimuth) to the target at this time

• targetTruthID: unique identifier for the target

• targetLon: target longitude at this time

• targetLat: target latitude at this time

• targetAlt: target altitude at this time

• targetHeading: target heading at this time

battleVerse/scenarioMaker documentation built on July 16, 2024, 4:21 a.m.