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track

Track segments to connect navigational waypoints

Syntax

[lattrk,lontrk] = track(waypts)
[lattrk,lontrk] = track(waypts,units)
[lattrk,lontrk] = track(lat,lon)
[lattrk,lontrk] = track(lat,lon,ellipsoid)
[lattrk,lontrk] = track(lat,lon,ellipsoid,units,npts)
[lattrk,lontrk] = track(method,lat,...)
trkpts = track(lat,lon...)

Description

[lattrk,lontrk] = track(waypts) returns points in lattrk and lontrk along a track between the waypoints provided in navigational track format in the two-column matrix waypts. The outputs are column vectors in which successive segments are delineated with NaNs.

[lattrk,lontrk] = track(waypts,units) specifies the units of the inputs and outputs, where units is any valid angle unit string. The default is 'degrees'.

[lattrk,lontrk] = track(lat,lon) allows the user to input the waypoints in two vectors, lat and lon.

[lattrk,lontrk] = track(lat,lon,ellipsoid) specifies the shape of the Earth using ellipsoid, which can be a referenceSphere, referenceEllipsoid, or oblateSpheroid object, or a vector of the form [semimajor_axis eccentricity]. The default ellipsoid is a unit sphere

[lattrk,lontrk] = track(lat,lon,ellipsoid,units,npts) establishes how many intermediate points are to be calculated for every track segment. By default, npts is 30.

[lattrk,lontrk] = track(method,lat,...) establishes the logic to be used to determine the intermediate points along the track between waypoints. Because this is a navigationally motivated function, the default method is 'rh', which results in rhumb line logic. Great circle logic can be specified with 'gc'.

trkpts = track(lat,lon...) compresses the output into one two-column matrix, trkpts, in which the first column represents latitudes and the second column, longitudes.

Examples

The track function is useful for generating data in order to display tracks. Lieutenant Sextant is the navigator of the USS Neversail. He is charged with plotting a track to take Neversail from the Straits of Gibraltar to Port Said, Egypt, the northern end of the Suez Canal. He has picked appropriate waypoints and now would like to display the track for his captain's approval.

First, display a chart of the Mediterranean Sea:

load coast
axesm('mercator','MapLatLimit',[28 47],'MapLonLimit',[-10 37],...
    'Grid','on','Frame','on','MeridianLabel','on','ParallelLabel','on')
geoshow(lat,long,'DisplayType','line','color','b')

These are the waypoints Lt. Sextant has selected:

waypoints = [36,-5; 36,-2; 38,5; 38,11; 35,13; 33,30; 31.5,32]

waypoints =
   36.0000   -5.0000
   36.0000   -2.0000
   38.0000    5.0000
   38.0000   11.0000
   35.0000   13.0000
   33.0000   30.0000
   31.5000   32.0000

Now display the track:

[lttrk,lntrk] = track('rh',waypoints,'degrees'); 
geoshow(lttrk,lntrk,'DisplayType','line','color','r')

With a display this clear, the captain gladly approves the plan.

See Also

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