

r  toggle whether counterclockwise traversal of the polygon returns a positive (the default) or negative result. 
s  toggle whether to return a signed result (the default) or not. 
l  toggle whether the vertices represent a polygon (the default) or a polyline. For a polyline, the number of points and the length of the path joining them is returned; the path is not closed and the area is not reported. 
e a f  specify the ellipsoid via the equatorial radius, a and the flattening, f. Setting f = 0 results in a sphere. Specify f < 0 for a prolate ellipsoid. A simple fraction, e.g., 1/297, is allowed for f. By default, the WGS84 ellipsoid is used, a = 6378137 m, f = 1/298.257223563. If entering vertices as UTM/UPS or MGRS coordinates, use the default ellipsoid, since the conversion of these coordinates to latitude and longitude always uses the WGS84 parameters. 
w  toggle the longitude first flag (it starts off); if the flag is on, then when reading geographic coordinates, longitude precedes latitude (this can be overridden by a hemisphere designator, N, S, E, W). 
p prec  set the output precision to prec (default 6); the perimeter is given (in meters) with prec digits after the decimal point; the area is given (in meters^2) with (prec  5) digits after the decimal point. 
G  use the series formulation for the geodesics. This is the default option and is recommended for terrestrial applications. This option, G, and the following three options, E, Q, and R, are mutually exclusive. 
E  use exact algorithms (based on elliptic integrals) for the geodesic calculations. These are more accurate than the (default) series expansions for f > 0.02. (But note that the implementation of areas in GeodesicExact uses a high order series and this is only accurate for modest flattenings.) 
Q  perform the calculation on the authalic sphere. The area calculation is accurate even if the flattening is large, provided the edges are sufficiently short. The perimeter calculation is not accurate. 
R  The lines joining the vertices are rhumb lines instead of geodesics. 
commentdelimiter commentdelim  set the comment delimiter to commentdelim (e.g., # or //). If set, the input lines will be scanned for this delimiter and, if found, the delimiter and the rest of the line will be removed prior to processing. For a given polygon, the last such string found will be appended to the output line (separated by a space). 
version  print version and exit. 
h  print usage and exit. 
help  print full documentation and exit. 
inputfile infile  read input from the file infile instead of from standard input; a file name of  stands for standard input. 
inputstring instring  read input from the string instring instead of from standard input. All occurrences of the line separator character (default is a semicolon) in instring are converted to newlines before the reading begins. 
lineseparator linesep  set the line separator character to linesep. By default this is a semicolon. 
outputfile outfile  write output to the file outfile instead of to standard output; a file name of  stands for standard output. 
Example (the area of the 100km MGRS square 18SWK)
Planimeter <<EOF 18n 500000 4400000 18n 600000 4400000 18n 600000 4500000 18n 500000 4500000 EOF => 4 400139.53295860 10007388597.1913The following code takes the output from gdalinfo and reports the area covered by the data (assuming the edges of the image are geodesics).
#! /bin/sh egrep ^((UpperLower) (LeftRight)Center)  sed e s/d /d/g e "s/ //g"  tr s (),\r\t  awk { if ($1 $2 == "UpperLeft") ul = $6 " " $5; else if ($1 $2 == "LowerLeft") ll = $6 " " $5; else if ($1 $2 == "UpperRight") ur = $6 " " $5; else if ($1 $2 == "LowerRight") lr = $6 " " $5; else if ($1 == "Center") { printf "%s\n%s\n%s\n%s\n\n", ul, ll, lr, ur; ul = ll = ur = lr = ""; } }  Planimeter  cut f3 d
GeoConvert(1), GeodSolve(1).An online version of this utility is availbable at <http://geographiclib.sourceforge.net/cgibin/Planimeter>.
The algorithm for the area of geodesic polygon is given in Section 6 of C. F. F. Karney, Algorithms for geodesics, J. Geodesy 87, 4355 (2013); DOI <https://dx.doi.org/10.1007/s001900120578z>; addenda: <http://geographiclib.sourceforge.net/geodaddenda.html>.
Planimeter was written by Charles Karney.
Planimeter was added to GeographicLib, <http://geographiclib.sourceforge.net>, in version 1.4.
GeographicLib 1.46  PLANIMETER (1)  20160214 
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