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interpm

Densify latitude-longitude sampling in lines or polygons

Syntax

[latout,lonout] = interpm(lat,lon,maxdiff)
[latout,lonout] = interpm(lat,lon,maxdiff,method)
[latout,lonout] = interpm(lat,lon,maxdiff,method,units)

Description

[latout,lonout] = interpm(lat,lon,maxdiff) fills in any gaps in latitude (lat) or longitude (lon) data vectors that are greater than a defined tolerance maxdiff apart in either dimension. The angle units of the three inputs need not be specified, but they must be identical. latout and lonout are the new latitude and longitude data vectors, in which any gaps larger than maxdiff in the original vectors have been filled with additional points. The default method of interpolation used by interpm is linear.

[latout,lonout] = interpm(lat,lon,maxdiff,method) interpolates between vector data coordinate points using a specified interpolation method. Valid interpolation methods are 'gc' for great circle, 'rh' for rhumb line, and 'lin' for linear interpolation.

[latout,lonout] = interpm(lat,lon,maxdiff,method,units) specifies the units used, where units is any valid angle unit. The default is 'degrees'.

Examples

collapse all

Define two vectors containing the latitude and longitude values for a set of vertices. In lat, note that a gap of 2 degrees exists between the values 2 and 4. Similarly, in lon, a gap of 2 degrees exists between the values 1 and 3.

lat = [1 2 4 5]; 
lon = [1 3 4 5];

Call interpm to fill in any gaps greater than 1 degree in either vector. For example, interpm interpolates and inserts the value 2 into the lon vector to fill the gap between the values 1 and 3, and inserts the value 1.5 in the lat vector for this new vertex. Similarly, interpm inserts the value 3 into the lat vector to fill the gap between the values 2 and 4, and inserts the value 3.5 in the lon vector for this new vertex. Now, the separation of adjacent vertices is no greater than maxdiff in either newlat or newlon.

maxdiff = 1;
[newlat,newlon] = interpm(lat,lon,maxdiff)
newlat = 6×1

    1.0000
    1.5000
    2.0000
    3.0000
    4.0000
    5.0000

newlon = 6×1

    1.0000
    2.0000
    3.0000
    3.5000
    4.0000
    5.0000

See Also

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Introduced before R2006a