mirror of https://github.com/wb2osz/direwolf.git
191 lines
7.1 KiB
C
191 lines
7.1 KiB
C
//LatLong- UTM conversion.c
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//Lat Long - UTM, UTM - Lat Long conversions
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#include <math.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "constants.h"
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#include "LatLong-UTMconversion.h"
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/*Reference ellipsoids derived from Peter H. Dana's website-
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http://www.utexas.edu/depts/grg/gcraft/notes/datum/elist.html
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Department of Geography, University of Texas at Austin
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Internet: pdana@mail.utexas.edu
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3/22/95
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Source
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Defense Mapping Agency. 1987b. DMA Technical Report: Supplement to Department of Defense World Geodetic System
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1984 Technical Report. Part I and II. Washington, DC: Defense Mapping Agency
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*/
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void LLtoUTM(int ReferenceEllipsoid, const double Lat, const double Long,
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double *UTMNorthing, double *UTMEasting, char* UTMZone)
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{
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//converts lat/long to UTM coords. Equations from USGS Bulletin 1532
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//East Longitudes are positive, West longitudes are negative.
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//North latitudes are positive, South latitudes are negative
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//Lat and Long are in decimal degrees
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//Written by Chuck Gantz- chuck.gantz@globalstar.com
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double a = ellipsoid[ReferenceEllipsoid].EquatorialRadius;
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double eccSquared = ellipsoid[ReferenceEllipsoid].eccentricitySquared;
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double k0 = 0.9996;
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double LongOrigin;
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double eccPrimeSquared;
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double N, T, C, A, M;
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//Make sure the longitude is between -180.00 .. 179.9
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double LongTemp = (Long+180)-(int)((Long+180)/360)*360-180; // -180.00 .. 179.9;
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double LatRad = Lat*deg2rad;
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double LongRad = LongTemp*deg2rad;
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double LongOriginRad;
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int ZoneNumber;
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ZoneNumber = (int)((LongTemp + 180)/6) + 1;
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if( Lat >= 56.0 && Lat < 64.0 && LongTemp >= 3.0 && LongTemp < 12.0 )
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ZoneNumber = 32;
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// Special zones for Svalbard
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if( Lat >= 72.0 && Lat < 84.0 )
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{
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if( LongTemp >= 0.0 && LongTemp < 9.0 ) ZoneNumber = 31;
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else if( LongTemp >= 9.0 && LongTemp < 21.0 ) ZoneNumber = 33;
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else if( LongTemp >= 21.0 && LongTemp < 33.0 ) ZoneNumber = 35;
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else if( LongTemp >= 33.0 && LongTemp < 42.0 ) ZoneNumber = 37;
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}
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LongOrigin = (ZoneNumber - 1)*6 - 180 + 3; //+3 puts origin in middle of zone
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LongOriginRad = LongOrigin * deg2rad;
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//compute the UTM Zone from the latitude and longitude
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sprintf(UTMZone, "%d%c", ZoneNumber, UTMLetterDesignator(Lat));
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eccPrimeSquared = (eccSquared)/(1-eccSquared);
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N = a/sqrt(1-eccSquared*sin(LatRad)*sin(LatRad));
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T = tan(LatRad)*tan(LatRad);
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C = eccPrimeSquared*cos(LatRad)*cos(LatRad);
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A = cos(LatRad)*(LongRad-LongOriginRad);
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M = a*((1 - eccSquared/4 - 3*eccSquared*eccSquared/64 - 5*eccSquared*eccSquared*eccSquared/256)*LatRad
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- (3*eccSquared/8 + 3*eccSquared*eccSquared/32 + 45*eccSquared*eccSquared*eccSquared/1024)*sin(2*LatRad)
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+ (15*eccSquared*eccSquared/256 + 45*eccSquared*eccSquared*eccSquared/1024)*sin(4*LatRad)
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- (35*eccSquared*eccSquared*eccSquared/3072)*sin(6*LatRad));
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*UTMEasting = (double)(k0*N*(A+(1-T+C)*A*A*A/6
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+ (5-18*T+T*T+72*C-58*eccPrimeSquared)*A*A*A*A*A/120)
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+ 500000.0);
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*UTMNorthing = (double)(k0*(M+N*tan(LatRad)*(A*A/2+(5-T+9*C+4*C*C)*A*A*A*A/24
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+ (61-58*T+T*T+600*C-330*eccPrimeSquared)*A*A*A*A*A*A/720)));
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if(Lat < 0)
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*UTMNorthing += 10000000.0; //10000000 meter offset for southern hemisphere
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}
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char UTMLetterDesignator(double Lat)
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{
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//This routine determines the correct UTM letter designator for the given latitude
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//returns 'Z' if latitude is outside the UTM limits of 84N to 80S
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//Written by Chuck Gantz- chuck.gantz@globalstar.com
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char LetterDesignator;
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if((84 >= Lat) && (Lat >= 72)) LetterDesignator = 'X';
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else if((72 > Lat) && (Lat >= 64)) LetterDesignator = 'W';
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else if((64 > Lat) && (Lat >= 56)) LetterDesignator = 'V';
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else if((56 > Lat) && (Lat >= 48)) LetterDesignator = 'U';
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else if((48 > Lat) && (Lat >= 40)) LetterDesignator = 'T';
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else if((40 > Lat) && (Lat >= 32)) LetterDesignator = 'S';
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else if((32 > Lat) && (Lat >= 24)) LetterDesignator = 'R';
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else if((24 > Lat) && (Lat >= 16)) LetterDesignator = 'Q';
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else if((16 > Lat) && (Lat >= 8)) LetterDesignator = 'P';
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else if(( 8 > Lat) && (Lat >= 0)) LetterDesignator = 'N';
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else if(( 0 > Lat) && (Lat >= -8)) LetterDesignator = 'M';
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else if((-8> Lat) && (Lat >= -16)) LetterDesignator = 'L';
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else if((-16 > Lat) && (Lat >= -24)) LetterDesignator = 'K';
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else if((-24 > Lat) && (Lat >= -32)) LetterDesignator = 'J';
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else if((-32 > Lat) && (Lat >= -40)) LetterDesignator = 'H';
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else if((-40 > Lat) && (Lat >= -48)) LetterDesignator = 'G';
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else if((-48 > Lat) && (Lat >= -56)) LetterDesignator = 'F';
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else if((-56 > Lat) && (Lat >= -64)) LetterDesignator = 'E';
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else if((-64 > Lat) && (Lat >= -72)) LetterDesignator = 'D';
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else if((-72 > Lat) && (Lat >= -80)) LetterDesignator = 'C';
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else LetterDesignator = 'Z'; //This is here as an error flag to show that the Latitude is outside the UTM limits
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return LetterDesignator;
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}
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void UTMtoLL(int ReferenceEllipsoid, const double UTMNorthing, const double UTMEasting, const char* UTMZone,
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double *Lat, double *Long )
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{
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//converts UTM coords to lat/long. Equations from USGS Bulletin 1532
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//East Longitudes are positive, West longitudes are negative.
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//North latitudes are positive, South latitudes are negative
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//Lat and Long are in decimal degrees.
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//Written by Chuck Gantz- chuck.gantz@globalstar.com
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double k0 = 0.9996;
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double a = ellipsoid[ReferenceEllipsoid].EquatorialRadius;
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double eccSquared = ellipsoid[ReferenceEllipsoid].eccentricitySquared;
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double eccPrimeSquared;
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double e1 = (1-sqrt(1-eccSquared))/(1+sqrt(1-eccSquared));
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double N1, T1, C1, R1, D, M;
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double LongOrigin;
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double mu, phi1, phi1Rad;
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double x, y;
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int ZoneNumber;
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char* ZoneLetter;
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int NorthernHemisphere; //1 for northern hemispher, 0 for southern
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x = UTMEasting - 500000.0; //remove 500,000 meter offset for longitude
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y = UTMNorthing;
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ZoneNumber = strtoul(UTMZone, &ZoneLetter, 10);
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if (*ZoneLetter == '\0')
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{
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NorthernHemisphere = 1; //no letter - assume northern hemisphere
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}
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else if((*ZoneLetter >= 'N' && *ZoneLetter <= 'X') ||
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(*ZoneLetter >= 'n' && *ZoneLetter <= 'x'))
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{
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NorthernHemisphere = 1; //point is in northern hemisphere
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}
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else
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{
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NorthernHemisphere = 0; //point is in southern hemisphere
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y -= 10000000.0; //remove 10,000,000 meter offset used for southern hemisphere
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}
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LongOrigin = (ZoneNumber - 1)*6 - 180 + 3; //+3 puts origin in middle of zone
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eccPrimeSquared = (eccSquared)/(1-eccSquared);
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M = y / k0;
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mu = M/(a*(1-eccSquared/4-3*eccSquared*eccSquared/64-5*eccSquared*eccSquared*eccSquared/256));
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phi1Rad = mu + (3*e1/2-27*e1*e1*e1/32)*sin(2*mu)
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+ (21*e1*e1/16-55*e1*e1*e1*e1/32)*sin(4*mu)
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+(151*e1*e1*e1/96)*sin(6*mu);
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phi1 = phi1Rad*rad2deg;
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N1 = a/sqrt(1-eccSquared*sin(phi1Rad)*sin(phi1Rad));
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T1 = tan(phi1Rad)*tan(phi1Rad);
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C1 = eccPrimeSquared*cos(phi1Rad)*cos(phi1Rad);
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R1 = a*(1-eccSquared)/pow(1-eccSquared*sin(phi1Rad)*sin(phi1Rad), 1.5);
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D = x/(N1*k0);
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*Lat = phi1Rad - (N1*tan(phi1Rad)/R1)*(D*D/2-(5+3*T1+10*C1-4*C1*C1-9*eccPrimeSquared)*D*D*D*D/24
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+(61+90*T1+298*C1+45*T1*T1-252*eccPrimeSquared-3*C1*C1)*D*D*D*D*D*D/720);
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*Lat = *Lat * rad2deg;
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*Long = (D-(1+2*T1+C1)*D*D*D/6+(5-2*C1+28*T1-3*C1*C1+8*eccPrimeSquared+24*T1*T1)
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*D*D*D*D*D/120)/cos(phi1Rad);
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*Long = LongOrigin + *Long * rad2deg;
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}
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