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
45 #include "degrees_converters.h"
48 * Convert a double to a string WITHOUT LOCALE.
50 * Following GPX specifications, decimal values are xsd:decimal
51 * So, they must use the period separator, not the localized one.
53 * The returned value must be freed by g_free.
55 char *a_coords_dtostr ( double d )
57 gchar *buffer = g_malloc(G_ASCII_DTOSTR_BUF_SIZE*sizeof(gchar));
58 g_ascii_dtostr (buffer, G_ASCII_DTOSTR_BUF_SIZE, (gdouble) d);
62 #define PIOVER180 0.01745329252
67 #define EquatorialRadius 6378137
68 #define EccentricitySquared 0.00669438
70 static char coords_utm_letter( double latitude );
72 int a_coords_utm_equal( const struct UTM *utm1, const struct UTM *utm2 )
74 return ( utm1->easting == utm2->easting && utm1->northing == utm2->northing && utm1->zone == utm2->zone );
77 double a_coords_utm_diff( const struct UTM *utm1, const struct UTM *utm2 )
79 static struct LatLon tmp1, tmp2;
80 if ( utm1->zone == utm2->zone ) {
81 return sqrt ( pow ( utm1->easting - utm2->easting, 2 ) + pow ( utm1->northing - utm2->northing, 2 ) );
83 a_coords_utm_to_latlon ( utm1, &tmp1 );
84 a_coords_utm_to_latlon ( utm2, &tmp2 );
85 return a_coords_latlon_diff ( &tmp1, &tmp2 );
89 double a_coords_latlon_diff ( const struct LatLon *ll1, const struct LatLon *ll2 )
91 static struct LatLon tmp1, tmp2;
92 tmp1.lat = ll1->lat * PIOVER180;
93 tmp1.lon = ll1->lon * PIOVER180;
94 tmp2.lat = ll2->lat * PIOVER180;
95 tmp2.lon = ll2->lon * PIOVER180;
96 return EquatorialRadius * acos(sin(tmp1.lat)*sin(tmp2.lat)+cos(tmp1.lat)*cos(tmp2.lat)*cos(tmp1.lon-tmp2.lon));
99 void a_coords_latlon_to_utm( const struct LatLon *latlon, struct UTM *utm )
103 double lat_rad, long_rad;
104 double long_origin, long_origin_rad;
105 double eccPrimeSquared;
106 double N, T, C, A, M;
108 double northing, easting;
110 longitude = latlon->lon;
111 latitude = latlon->lat;
113 /* We want the longitude within -180..180. */
114 if ( longitude < -180.0 )
116 if ( longitude > 180.0 )
120 lat_rad = latitude * M_PI / 180.0;
121 long_rad = longitude * M_PI / 180.0;
122 zone = (int) ( ( longitude + 180 ) / 6 ) + 1;
123 if ( latitude >= 56.0 && latitude < 64.0 &&
124 longitude >= 3.0 && longitude < 12.0 )
126 /* Special zones for Svalbard. */
127 if ( latitude >= 72.0 && latitude < 84.0 )
129 if ( longitude >= 0.0 && longitude < 9.0 ) zone = 31;
130 else if ( longitude >= 9.0 && longitude < 21.0 ) zone = 33;
131 else if ( longitude >= 21.0 && longitude < 33.0 ) zone = 35;
132 else if ( longitude >= 33.0 && longitude < 42.0 ) zone = 37;
134 long_origin = ( zone - 1 ) * 6 - 180 + 3; /* +3 puts origin in middle of zone */
135 long_origin_rad = long_origin * M_PI / 180.0;
136 eccPrimeSquared = EccentricitySquared / ( 1.0 - EccentricitySquared );
137 N = EquatorialRadius / sqrt( 1.0 - EccentricitySquared * sin( lat_rad ) * sin( lat_rad ) );
138 T = tan( lat_rad ) * tan( lat_rad );
139 C = eccPrimeSquared * cos( lat_rad ) * cos( lat_rad );
140 A = cos( lat_rad ) * ( long_rad - long_origin_rad );
141 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 ) );
143 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;
145 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 ) );
146 if ( latitude < 0.0 )
147 northing += 10000000.0; /* 1e7 meter offset for southern hemisphere */
149 utm->northing = northing;
150 utm->easting = easting;
152 utm->letter = coords_utm_letter( latitude );
158 static char coords_utm_letter( double latitude )
160 /* This routine determines the correct UTM letter designator for the
161 ** given latitude. It returns 'Z' if the latitude is outside the UTM
162 ** limits of 84N to 80S.
164 if ( latitude <= 84.0 && latitude >= 72.0 ) return 'X';
165 else if ( latitude < 72.0 && latitude >= 64.0 ) return 'W';
166 else if ( latitude < 64.0 && latitude >= 56.0 ) return 'V';
167 else if ( latitude < 56.0 && latitude >= 48.0 ) return 'U';
168 else if ( latitude < 48.0 && latitude >= 40.0 ) return 'T';
169 else if ( latitude < 40.0 && latitude >= 32.0 ) return 'S';
170 else if ( latitude < 32.0 && latitude >= 24.0 ) return 'R';
171 else if ( latitude < 24.0 && latitude >= 16.0 ) return 'Q';
172 else if ( latitude < 16.0 && latitude >= 8.0 ) return 'P';
173 else if ( latitude < 8.0 && latitude >= 0.0 ) return 'N';
174 else if ( latitude < 0.0 && latitude >= -8.0 ) return 'M';
175 else if ( latitude < -8.0 && latitude >= -16.0 ) return 'L';
176 else if ( latitude < -16.0 && latitude >= -24.0 ) return 'K';
177 else if ( latitude < -24.0 && latitude >= -32.0 ) return 'J';
178 else if ( latitude < -32.0 && latitude >= -40.0 ) return 'H';
179 else if ( latitude < -40.0 && latitude >= -48.0 ) return 'G';
180 else if ( latitude < -48.0 && latitude >= -56.0 ) return 'F';
181 else if ( latitude < -56.0 && latitude >= -64.0 ) return 'E';
182 else if ( latitude < -64.0 && latitude >= -72.0 ) return 'D';
183 else if ( latitude < -72.0 && latitude >= -80.0 ) return 'C';
189 void a_coords_utm_to_latlon( const struct UTM *utm, struct LatLon *latlon )
191 double northing, easting;
195 double eccPrimeSquared;
197 double N1, T1, C1, R1, D, M;
200 int northernHemisphere; /* 1 for northern hemisphere, 0 for southern */
201 double latitude, longitude;
203 northing = utm->northing;
204 easting = utm->easting;
206 letter[0] = utm->letter;
209 x = easting - 500000.0; /* remove 500000 meter offset */
211 if ( ( *letter - 'N' ) >= 0 )
212 northernHemisphere = 1; /* northern hemisphere */
215 northernHemisphere = 0; /* southern hemisphere */
216 y -= 10000000.0; /* remove 1e7 meter offset */
218 long_origin = ( zone - 1 ) * 6 - 180 + 3; /* +3 puts origin in middle of zone */
219 eccPrimeSquared = EccentricitySquared / ( 1.0 - EccentricitySquared );
220 e1 = ( 1.0 - sqrt( 1.0 - EccentricitySquared ) ) / ( 1.0 + sqrt( 1.0 - EccentricitySquared ) );
222 mu = M / ( EquatorialRadius * ( 1.0 - EccentricitySquared / 4 - 3 * EccentricitySquared * EccentricitySquared / 64 - 5 * EccentricitySquared * EccentricitySquared * EccentricitySquared / 256 ) );
223 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 );
224 N1 = EquatorialRadius / sqrt( 1.0 - EccentricitySquared * sin( phi1_rad ) * sin( phi1_rad ) );
225 T1 = tan( phi1_rad ) * tan( phi1_rad );
226 C1 = eccPrimeSquared * cos( phi1_rad ) * cos( phi1_rad );
227 R1 = EquatorialRadius * ( 1.0 - EccentricitySquared ) / pow( 1.0 - EccentricitySquared * sin( phi1_rad ) * sin( phi1_rad ), 1.5 );
229 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 );
230 latitude = latitude * 180.0 / M_PI;
231 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 );
232 longitude = long_origin + longitude * 180.0 / M_PI;
236 latlon->lat = latitude;
237 latlon->lon = longitude;
241 void a_coords_latlon_to_string ( const struct LatLon *latlon,
245 g_return_if_fail ( latlon != NULL );
247 vik_degree_format_t format = a_vik_get_degree_format ();
250 case VIK_DEGREE_FORMAT_DDD:
251 *lat = convert_lat_dec_to_ddd ( latlon->lat );
252 *lon = convert_lon_dec_to_ddd ( latlon->lon );
254 case VIK_DEGREE_FORMAT_DMM:
255 *lat = convert_lat_dec_to_dmm ( latlon->lat );
256 *lon = convert_lon_dec_to_dmm ( latlon->lon );
258 case VIK_DEGREE_FORMAT_DMS:
259 *lat = convert_lat_dec_to_dms ( latlon->lat );
260 *lon = convert_lon_dec_to_dms ( latlon->lon );
263 g_critical("Houston, we've had a problem. format=%d", format);