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| author | Frank Warmerdam <warmerdam@pobox.com> | 1999-03-18 16:34:52 +0000 |
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| committer | Frank Warmerdam <warmerdam@pobox.com> | 1999-03-18 16:34:52 +0000 |
| commit | 565a4bd035b9d4a83955808efef20f1d8dfa24cf (patch) | |
| tree | 75785fc897708023f1ccdaf40079afcbaaf0fd3a /man/man1/geod.1 | |
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diff --git a/man/man1/geod.1 b/man/man1/geod.1 new file mode 100644 index 00000000..36f32717 --- /dev/null +++ b/man/man1/geod.1 @@ -0,0 +1,202 @@ +.\" @(#)geod.1 - 1.1 +.nr LL 5.5i +.ad b +.hy 1 +.TH GEOD 1 "94/10/29 Rel. 4, Ver. BETA" "GIE" +.SH NAME +geod \- direct geodesic computations +.br +invgeod \- inverse geodesic computations +.SH SYNOPSIS +.B geod +[ +.B \-afFIlptwW +[ +.I args +] ] [ +.B +args +] +file[s] +.br +.B invgeod +[ +.B \-afFIlptwW +[ +.I args +] ] [ +.B +args +] +file[s] +.SH DESCRIPTION +.I Geod +(direct) and +.I invgeod +(inverse) +perform geodesic (\(``Great Circle\('') computations for determining +latitude, longitude and back azimuth of a terminus point +given a initial point latitude, longitude, azimuth and distance (direct) or +the forward and back azimuths and distance between an initial and +terminus point latitudes and longitudes (inverse). +.PP +The following runline control parameters can appear in any order: +.TP +.B \-I +Specifies that the inverse geodesic computation is to be performed. +May be used with execution of +.B goed +as an alternative to +.B invgeod +execution. +.TP +.B \-a +Latitude and longitudes of the initial and terminal points, +forward and back azimuths and distance are output. +.TP +.BI \-t "a" +.I A +specifies a character employed as the first character to denote +a control line to be passed through without processing. +.TP +.BI \-le +Gives a listing of all the ellipsoids that may be selected with the +.B +ellps= +option. +.TP +.BI \-lu +Gives a listing of all the units that may be selected with the +.B +units= +option. +.TP +.BI \-[f|F] " format" +.I Format +is a +.I printf +format string to control the output form of the geographic coordinate values +(\fBf\fR) or distance value (\fBF\fR). +The default mode is DMS for geographic coordinates and "%.3f" for distance. +.TP +.BI \-[w|W] n +.I N +is the number of significant fractional digits to employ for +seconds output (when the option is not specified, +.B \-w3 +is assumed). +When +.B \-W +is employed the fields will be constant width with leading zeroes. +.TP +.B \-p +This option causes the azimuthal values to be output as unsigned +numbers between 0 and 360\(de. +.PP +The +.B +args +run-line arguments are associated with geodetic parameters +for specifying the ellipsoidal or sphere to use. +See +.B proj +documentation for full list of these parameters and contrl. +The options are processed in left to right order +from the run line. +Reentry of an option is ignored with the first occurance assumed to +be the desired value. +.PP +One or more +.I files +(processed in left to right order) +specify the source of data to be transformed. +A \- will specify the location of processing standard input. +If no files are specified, the input is assumed to be from +.I stdin. +.PP +For direct determinations input data must be in latitude, +longitude, azimuth and distance order and output will be +latitude, longitude and back azimuth of the terminus point. +Latitude, longitude of the initial and terminus point are +input for the inverse mode and respective forward and back +azimuth from the initial and terminus points are output along +with the distance between the points. +.PP +Input geographic coordinates +(latitude and longitude) and azimuthal data must be in DMS format and input +distance data must be in units consistent with the ellipsoid +major axis or sphere radius units. +Output geographic coordinates will be in DMS +(if the +.B \-f +switch is not employed) to 0.001" +with trailing, zero-valued minute-second fields deleted. +Output distance data will be in the same units as the ellipsoid or +sphere radius. +.PP +The Earth's ellipsoidal figure may be selected in the same +manner as program +.B proj +by using +.B "+ellps=, +a=, +es=," +etc. +.PP +.I Geod +may also be used to determine intermediate points along either +a geodesic line between two points or along an arc of specified distance +from a geographic point. +In both cases an initial point must be specified with +.BI +lat_1= lat +and +.BI +lon_1= lon +parameters and either a terminus point +.BI +lat_2= lat +and +.BI +lon_2= lon +or a distance and azimuth from the initial point with +.BI +S= distance +and +.BI +A= azimuth +must be specified. +.PP +If points along a geodesic are to be determined then either +.BI +n_S= integer +specifying the number of intermediate points and/or +.BI +del_S= distance +specifying the incremental distance between points must be specified. +.PP +To determine points along an arc equidistant from the initial point both +.BI +del_A= angle +and +.BI +n_A= integer +must be specified which determine the respective angular increments +and number of points to be determined. +.RE +.SH EXAMPLE +The following script determines the geodesic azimuths and distance in +U.S. stature miles from Boston, MA, to Portland, OR: +.RS 5 + \f(CWgeod +ellps=clrk66 <<EOF -I +units=us-mi + 42d15'N 71d07'W 45d31'N 123d41'W + EOF\fR +.RE +which gives the results: +.RS 5 + \f(CW-66d31'50.141" 75d39'13.083" 2587.504 +.RE +where the first two values are the +azimuth from Boston to Portland, the back azimuth from Portland to +Boston followed by the distance. +.PP +An example of forward geodesic use is to use the Boston location and determine +Portland's location by azimuth and distance: +.RS 5 + \f(CWgeod +ellps=clrk66 <<EOF +units=us-mi + 42d15'N 71d07'W -66d31'50.141" 2587.504 + EOF\fR +.RE +which gives: +.RS 5 + \f(CW45d31'0.003"N 123d40'59.985"W 75d39'13.094"\fR +.RE +Note: lack of precision in the distance value compromises +the precision of the Portland location. +.SH SEE ALSO +Thomas, P.D., 1970, +.I "Spheroidal Geodesics, Reference Systems & Local Geometry:" +U.S. Naval Oceanographic Office, S-138. |
