4 http://acme.com/software/coords/
5 I (Evan Battaglia <viking@greentorch.org>) have only made some small changes such as
6 renaming functions and defining LatLon and UTM structs.
7 2004-02-10 -- I also added a function of my own -- a_coords_utm_diff() -- that I felt belonged in coords.c
8 2004-02-21 -- I also added a_coords_utm_equal().
9 2005-11-23 -- Added a_coords_dtostr() for lack of a better place.
12 /* coords.h - include file for coords routines
14 ** Copyright © 2001 by Jef Poskanzer <jef@acme.com>.
15 ** All rights reserved.
17 ** Redistribution and use in source and binary forms, with or without
18 ** modification, are permitted provided that the following conditions
20 ** 1. Redistributions of source code must retain the above copyright
21 ** notice, this list of conditions and the following disclaimer.
22 ** 2. Redistributions in binary form must reproduce the above copyright
23 ** notice, this list of conditions and the following disclaimer in the
24 ** documentation and/or other materials provided with the distribution.
26 ** THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
27 ** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 ** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 ** ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
30 ** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 ** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 ** OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 ** HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 ** OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
54 #include "degrees_converters.h"
57 * Convert a double to a string WITHOUT LOCALE.
59 * Following GPX specifications, decimal values are xsd:decimal
60 * So, they must use the period separator, not the localized one.
62 * The returned value must be freed by g_free.
64 char *a_coords_dtostr ( double d )
66 gchar *buffer = g_malloc(G_ASCII_DTOSTR_BUF_SIZE*sizeof(gchar));
67 g_ascii_dtostr (buffer, G_ASCII_DTOSTR_BUF_SIZE, (gdouble) d);
71 #define PIOVER180 0.01745329252
76 #define EquatorialRadius 6378137
77 #define EccentricitySquared 0.00669438
79 static char coords_utm_letter( double latitude );
81 int a_coords_utm_equal( const struct UTM *utm1, const struct UTM *utm2 )
83 return ( utm1->easting == utm2->easting && utm1->northing == utm2->northing && utm1->zone == utm2->zone );
86 double a_coords_utm_diff( const struct UTM *utm1, const struct UTM *utm2 )
88 static struct LatLon tmp1, tmp2;
89 if ( utm1->zone == utm2->zone ) {
90 return sqrt ( pow ( utm1->easting - utm2->easting, 2 ) + pow ( utm1->northing - utm2->northing, 2 ) );
92 a_coords_utm_to_latlon ( utm1, &tmp1 );
93 a_coords_utm_to_latlon ( utm2, &tmp2 );
94 return a_coords_latlon_diff ( &tmp1, &tmp2 );
98 double a_coords_latlon_diff ( const struct LatLon *ll1, const struct LatLon *ll2 )
100 static struct LatLon tmp1, tmp2;
102 tmp1.lat = ll1->lat * PIOVER180;
103 tmp1.lon = ll1->lon * PIOVER180;
104 tmp2.lat = ll2->lat * PIOVER180;
105 tmp2.lon = ll2->lon * PIOVER180;
106 tmp3 = EquatorialRadius * acos(sin(tmp1.lat)*sin(tmp2.lat)+cos(tmp1.lat)*cos(tmp2.lat)*cos(tmp1.lon-tmp2.lon));
107 // For very small differences we can sometimes get NaN returned
108 return isnan(tmp3)?0:tmp3;
111 void a_coords_latlon_to_utm( const struct LatLon *latlon, struct UTM *utm )
115 double lat_rad, long_rad;
116 double long_origin, long_origin_rad;
117 double eccPrimeSquared;
118 double N, T, C, A, M;
120 double northing, easting;
122 longitude = latlon->lon;
123 latitude = latlon->lat;
125 /* We want the longitude within -180..180. */
126 if ( longitude < -180.0 )
128 if ( longitude > 180.0 )
132 lat_rad = DEG2RAD(latitude);
133 long_rad = DEG2RAD(longitude);
134 zone = (int) ( ( longitude + 180 ) / 6 ) + 1;
135 if ( latitude >= 56.0 && latitude < 64.0 &&
136 longitude >= 3.0 && longitude < 12.0 )
138 /* Special zones for Svalbard. */
139 if ( latitude >= 72.0 && latitude < 84.0 )
141 if ( longitude >= 0.0 && longitude < 9.0 ) zone = 31;
142 else if ( longitude >= 9.0 && longitude < 21.0 ) zone = 33;
143 else if ( longitude >= 21.0 && longitude < 33.0 ) zone = 35;
144 else if ( longitude >= 33.0 && longitude < 42.0 ) zone = 37;
146 long_origin = ( zone - 1 ) * 6 - 180 + 3; /* +3 puts origin in middle of zone */
147 long_origin_rad = DEG2RAD(long_origin);
148 eccPrimeSquared = EccentricitySquared / ( 1.0 - EccentricitySquared );
149 N = EquatorialRadius / sqrt( 1.0 - EccentricitySquared * sin( lat_rad ) * sin( lat_rad ) );
150 T = tan( lat_rad ) * tan( lat_rad );
151 C = eccPrimeSquared * cos( lat_rad ) * cos( lat_rad );
152 A = cos( lat_rad ) * ( long_rad - long_origin_rad );
153 M = EquatorialRadius * ( ( 1.0 - EccentricitySquared / 4 - 3 * EccentricitySquared * EccentricitySquared / 64 - 5 * EccentricitySquared * EccentricitySquared * EccentricitySquared / 256 ) * lat_rad - ( 3 * EccentricitySquared / 8 + 3 * EccentricitySquared * EccentricitySquared / 32 + 45 * EccentricitySquared * EccentricitySquared * EccentricitySquared / 1024 ) * sin( 2 * lat_rad ) + ( 15 * EccentricitySquared * EccentricitySquared / 256 + 45 * EccentricitySquared * EccentricitySquared * EccentricitySquared / 1024 ) * sin( 4 * lat_rad ) - ( 35 * EccentricitySquared * EccentricitySquared * EccentricitySquared / 3072 ) * sin( 6 * lat_rad ) );
155 K0 * N * ( A + ( 1 - T + C ) * A * A * A / 6 + ( 5 - 18 * T + T * T + 72 * C - 58 * eccPrimeSquared ) * A * A * A * A * A / 120 ) + 500000.0;
157 K0 * ( M + N * tan( lat_rad ) * ( A * A / 2 + ( 5 - T + 9 * C + 4 * C * C ) * A * A * A * A / 24 + ( 61 - 58 * T + T * T + 600 * C - 330 * eccPrimeSquared ) * A * A * A * A * A * A / 720 ) );
158 if ( latitude < 0.0 )
159 northing += 10000000.0; /* 1e7 meter offset for southern hemisphere */
161 utm->northing = northing;
162 utm->easting = easting;
164 utm->letter = coords_utm_letter( latitude );
170 static char coords_utm_letter( double latitude )
172 /* This routine determines the correct UTM letter designator for the
173 ** given latitude. It returns 'Z' if the latitude is outside the UTM
174 ** limits of 84N to 80S.
176 if ( latitude <= 84.0 && latitude >= 72.0 ) return 'X';
177 else if ( latitude < 72.0 && latitude >= 64.0 ) return 'W';
178 else if ( latitude < 64.0 && latitude >= 56.0 ) return 'V';
179 else if ( latitude < 56.0 && latitude >= 48.0 ) return 'U';
180 else if ( latitude < 48.0 && latitude >= 40.0 ) return 'T';
181 else if ( latitude < 40.0 && latitude >= 32.0 ) return 'S';
182 else if ( latitude < 32.0 && latitude >= 24.0 ) return 'R';
183 else if ( latitude < 24.0 && latitude >= 16.0 ) return 'Q';
184 else if ( latitude < 16.0 && latitude >= 8.0 ) return 'P';
185 else if ( latitude < 8.0 && latitude >= 0.0 ) return 'N';
186 else if ( latitude < 0.0 && latitude >= -8.0 ) return 'M';
187 else if ( latitude < -8.0 && latitude >= -16.0 ) return 'L';
188 else if ( latitude < -16.0 && latitude >= -24.0 ) return 'K';
189 else if ( latitude < -24.0 && latitude >= -32.0 ) return 'J';
190 else if ( latitude < -32.0 && latitude >= -40.0 ) return 'H';
191 else if ( latitude < -40.0 && latitude >= -48.0 ) return 'G';
192 else if ( latitude < -48.0 && latitude >= -56.0 ) return 'F';
193 else if ( latitude < -56.0 && latitude >= -64.0 ) return 'E';
194 else if ( latitude < -64.0 && latitude >= -72.0 ) return 'D';
195 else if ( latitude < -72.0 && latitude >= -80.0 ) return 'C';
201 void a_coords_utm_to_latlon( const struct UTM *utm, struct LatLon *latlon )
203 double northing, easting;
207 double eccPrimeSquared;
209 double N1, T1, C1, R1, D, M;
212 int northernHemisphere; /* 1 for northern hemisphere, 0 for southern */
213 double latitude, longitude;
215 northing = utm->northing;
216 easting = utm->easting;
218 letter[0] = utm->letter;
221 x = easting - 500000.0; /* remove 500000 meter offset */
223 if ( ( *letter - 'N' ) >= 0 )
224 northernHemisphere = 1; /* northern hemisphere */
227 northernHemisphere = 0; /* southern hemisphere */
228 y -= 10000000.0; /* remove 1e7 meter offset */
230 long_origin = ( zone - 1 ) * 6 - 180 + 3; /* +3 puts origin in middle of zone */
231 eccPrimeSquared = EccentricitySquared / ( 1.0 - EccentricitySquared );
232 e1 = ( 1.0 - sqrt( 1.0 - EccentricitySquared ) ) / ( 1.0 + sqrt( 1.0 - EccentricitySquared ) );
234 mu = M / ( EquatorialRadius * ( 1.0 - EccentricitySquared / 4 - 3 * EccentricitySquared * EccentricitySquared / 64 - 5 * EccentricitySquared * EccentricitySquared * EccentricitySquared / 256 ) );
235 phi1_rad = mu + ( 3 * e1 / 2 - 27 * e1 * e1 * e1 / 32 )* sin( 2 * mu ) + ( 21 * e1 * e1 / 16 - 55 * e1 * e1 * e1 * e1 / 32 ) * sin( 4 * mu ) + ( 151 * e1 * e1 * e1 / 96 ) * sin( 6 *mu );
236 N1 = EquatorialRadius / sqrt( 1.0 - EccentricitySquared * sin( phi1_rad ) * sin( phi1_rad ) );
237 T1 = tan( phi1_rad ) * tan( phi1_rad );
238 C1 = eccPrimeSquared * cos( phi1_rad ) * cos( phi1_rad );
239 R1 = EquatorialRadius * ( 1.0 - EccentricitySquared ) / pow( 1.0 - EccentricitySquared * sin( phi1_rad ) * sin( phi1_rad ), 1.5 );
241 latitude = phi1_rad - ( N1 * tan( phi1_rad ) / R1 ) * ( D * D / 2 -( 5 + 3 * T1 + 10 * C1 - 4 * C1 * C1 - 9 * eccPrimeSquared ) * D * D * D * D / 24 + ( 61 + 90 * T1 + 298 * C1 + 45 * T1 * T1 - 252 * eccPrimeSquared - 3 * C1 * C1 ) * D * D * D * D * D * D / 720 );
242 latitude = RAD2DEG(latitude);
243 longitude = ( D - ( 1 + 2 * T1 + C1 ) * D * D * D / 6 + ( 5 - 2 * C1 + 28 * T1 - 3 * C1 * C1 + 8 * eccPrimeSquared + 24 * T1 * T1 ) * D * D * D * D * D / 120 ) / cos( phi1_rad );
244 longitude = long_origin + RAD2DEG(longitude);
248 latlon->lat = latitude;
249 latlon->lon = longitude;
253 void a_coords_latlon_to_string ( const struct LatLon *latlon,
257 g_return_if_fail ( latlon != NULL );
259 vik_degree_format_t format = a_vik_get_degree_format ();
262 case VIK_DEGREE_FORMAT_DDD:
263 *lat = convert_lat_dec_to_ddd ( latlon->lat );
264 *lon = convert_lon_dec_to_ddd ( latlon->lon );
266 case VIK_DEGREE_FORMAT_DMM:
267 *lat = convert_lat_dec_to_dmm ( latlon->lat );
268 *lon = convert_lon_dec_to_dmm ( latlon->lon );
270 case VIK_DEGREE_FORMAT_DMS:
271 *lat = convert_lat_dec_to_dms ( latlon->lat );
272 *lon = convert_lon_dec_to_dms ( latlon->lon );
275 g_critical("Houston, we've had a problem. format=%d", format);