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
57 #define DEG2RAD(x) ((x)*(M_PI/180))
58 #define RAD2DEG(x) ((x)*(180/M_PI))
60 #include "degrees_converters.h"
61 #include "misc/fpconv.h"
66 void a_coords_dtostr_buffer ( double d, char buffer[COORDS_STR_BUFFER_SIZE] )
68 int str_len = fpconv_dtoa(d, buffer);
69 if ( str_len < COORDS_STR_BUFFER_SIZE )
70 buffer[str_len] = '\0';
72 buffer[COORDS_STR_BUFFER_SIZE-1] = '\0';
76 * Convert a double to a string WITHOUT LOCALE.
78 * Following GPX specifications, decimal values are xsd:decimal
79 * So, they must use the period separator, not the localized one.
81 * The returned value must be freed by g_free.
83 char *a_coords_dtostr ( double d )
85 gchar *buffer = g_malloc(G_ASCII_DTOSTR_BUF_SIZE*sizeof(gchar));
86 // Note that this doesn't necessary produce the shortest string
87 //g_ascii_formatd (buffer, G_ASCII_DTOSTR_BUF_SIZE, "%.9lf", (gdouble)d);
88 // Thus use third party code:
89 a_coords_dtostr_buffer ( d, buffer );
93 #define PIOVER180 0.01745329252
98 #define EquatorialRadius 6378137
99 #define EccentricitySquared 0.00669438
101 static char coords_utm_letter( double latitude );
103 int a_coords_utm_equal( const struct UTM *utm1, const struct UTM *utm2 )
105 return ( utm1->easting == utm2->easting && utm1->northing == utm2->northing && utm1->zone == utm2->zone );
108 double a_coords_utm_diff( const struct UTM *utm1, const struct UTM *utm2 )
110 static struct LatLon tmp1, tmp2;
111 if ( utm1->zone == utm2->zone ) {
112 return sqrt ( pow ( utm1->easting - utm2->easting, 2 ) + pow ( utm1->northing - utm2->northing, 2 ) );
114 a_coords_utm_to_latlon ( utm1, &tmp1 );
115 a_coords_utm_to_latlon ( utm2, &tmp2 );
116 return a_coords_latlon_diff ( &tmp1, &tmp2 );
120 double a_coords_latlon_diff ( const struct LatLon *ll1, const struct LatLon *ll2 )
122 static struct LatLon tmp1, tmp2;
124 tmp1.lat = ll1->lat * PIOVER180;
125 tmp1.lon = ll1->lon * PIOVER180;
126 tmp2.lat = ll2->lat * PIOVER180;
127 tmp2.lon = ll2->lon * PIOVER180;
128 tmp3 = EquatorialRadius * acos(sin(tmp1.lat)*sin(tmp2.lat)+cos(tmp1.lat)*cos(tmp2.lat)*cos(tmp1.lon-tmp2.lon));
129 // For very small differences we can sometimes get NaN returned
130 return isnan(tmp3)?0:tmp3;
133 void a_coords_latlon_to_utm( const struct LatLon *latlon, struct UTM *utm )
137 double lat_rad, long_rad;
138 double long_origin, long_origin_rad;
139 double eccPrimeSquared;
140 double N, T, C, A, M;
142 double northing, easting;
144 longitude = latlon->lon;
145 latitude = latlon->lat;
147 /* We want the longitude within -180..180. */
148 if ( longitude < -180.0 )
150 if ( longitude > 180.0 )
154 lat_rad = DEG2RAD(latitude);
155 long_rad = DEG2RAD(longitude);
156 zone = (int) ( ( longitude + 180 ) / 6 ) + 1;
157 if ( latitude >= 56.0 && latitude < 64.0 &&
158 longitude >= 3.0 && longitude < 12.0 )
160 /* Special zones for Svalbard. */
161 if ( latitude >= 72.0 && latitude < 84.0 )
163 if ( longitude >= 0.0 && longitude < 9.0 ) zone = 31;
164 else if ( longitude >= 9.0 && longitude < 21.0 ) zone = 33;
165 else if ( longitude >= 21.0 && longitude < 33.0 ) zone = 35;
166 else if ( longitude >= 33.0 && longitude < 42.0 ) zone = 37;
168 long_origin = ( zone - 1 ) * 6 - 180 + 3; /* +3 puts origin in middle of zone */
169 long_origin_rad = DEG2RAD(long_origin);
170 eccPrimeSquared = EccentricitySquared / ( 1.0 - EccentricitySquared );
171 N = EquatorialRadius / sqrt( 1.0 - EccentricitySquared * sin( lat_rad ) * sin( lat_rad ) );
172 T = tan( lat_rad ) * tan( lat_rad );
173 C = eccPrimeSquared * cos( lat_rad ) * cos( lat_rad );
174 A = cos( lat_rad ) * ( long_rad - long_origin_rad );
175 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 ) );
177 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;
179 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 ) );
180 if ( latitude < 0.0 )
181 northing += 10000000.0; /* 1e7 meter offset for southern hemisphere */
183 utm->northing = northing;
184 utm->easting = easting;
186 utm->letter = coords_utm_letter( latitude );
192 static char coords_utm_letter( double latitude )
194 /* This routine determines the correct UTM letter designator for the
195 ** given latitude. It returns 'Z' if the latitude is outside the UTM
196 ** limits of 84N to 80S.
198 if ( latitude <= 84.0 && latitude >= 72.0 ) return 'X';
199 else if ( latitude < 72.0 && latitude >= 64.0 ) return 'W';
200 else if ( latitude < 64.0 && latitude >= 56.0 ) return 'V';
201 else if ( latitude < 56.0 && latitude >= 48.0 ) return 'U';
202 else if ( latitude < 48.0 && latitude >= 40.0 ) return 'T';
203 else if ( latitude < 40.0 && latitude >= 32.0 ) return 'S';
204 else if ( latitude < 32.0 && latitude >= 24.0 ) return 'R';
205 else if ( latitude < 24.0 && latitude >= 16.0 ) return 'Q';
206 else if ( latitude < 16.0 && latitude >= 8.0 ) return 'P';
207 else if ( latitude < 8.0 && latitude >= 0.0 ) return 'N';
208 else if ( latitude < 0.0 && latitude >= -8.0 ) return 'M';
209 else if ( latitude < -8.0 && latitude >= -16.0 ) return 'L';
210 else if ( latitude < -16.0 && latitude >= -24.0 ) return 'K';
211 else if ( latitude < -24.0 && latitude >= -32.0 ) return 'J';
212 else if ( latitude < -32.0 && latitude >= -40.0 ) return 'H';
213 else if ( latitude < -40.0 && latitude >= -48.0 ) return 'G';
214 else if ( latitude < -48.0 && latitude >= -56.0 ) return 'F';
215 else if ( latitude < -56.0 && latitude >= -64.0 ) return 'E';
216 else if ( latitude < -64.0 && latitude >= -72.0 ) return 'D';
217 else if ( latitude < -72.0 && latitude >= -80.0 ) return 'C';
223 void a_coords_utm_to_latlon( const struct UTM *utm, struct LatLon *latlon )
225 double northing, easting;
229 double eccPrimeSquared;
231 double N1, T1, C1, R1, D, M;
234 double latitude, longitude;
236 northing = utm->northing;
237 easting = utm->easting;
239 letter[0] = utm->letter;
242 x = easting - 500000.0; /* remove 500000 meter offset */
244 if ( ( *letter - 'N' ) < 0 ) {
245 /* southern hemisphere */
246 y -= 10000000.0; /* remove 1e7 meter offset */
249 long_origin = ( zone - 1 ) * 6 - 180 + 3; /* +3 puts origin in middle of zone */
250 eccPrimeSquared = EccentricitySquared / ( 1.0 - EccentricitySquared );
251 e1 = ( 1.0 - sqrt( 1.0 - EccentricitySquared ) ) / ( 1.0 + sqrt( 1.0 - EccentricitySquared ) );
253 mu = M / ( EquatorialRadius * ( 1.0 - EccentricitySquared / 4 - 3 * EccentricitySquared * EccentricitySquared / 64 - 5 * EccentricitySquared * EccentricitySquared * EccentricitySquared / 256 ) );
254 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 );
255 N1 = EquatorialRadius / sqrt( 1.0 - EccentricitySquared * sin( phi1_rad ) * sin( phi1_rad ) );
256 T1 = tan( phi1_rad ) * tan( phi1_rad );
257 C1 = eccPrimeSquared * cos( phi1_rad ) * cos( phi1_rad );
258 R1 = EquatorialRadius * ( 1.0 - EccentricitySquared ) / pow( 1.0 - EccentricitySquared * sin( phi1_rad ) * sin( phi1_rad ), 1.5 );
260 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 );
261 latitude = RAD2DEG(latitude);
262 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 );
263 longitude = long_origin + RAD2DEG(longitude);
267 latlon->lat = latitude;
268 latlon->lon = longitude;
272 void a_coords_latlon_to_string ( const struct LatLon *latlon,
276 g_return_if_fail ( latlon != NULL );
278 vik_degree_format_t format = a_vik_get_degree_format ();
281 case VIK_DEGREE_FORMAT_DDD:
282 *lat = convert_lat_dec_to_ddd ( latlon->lat );
283 *lon = convert_lon_dec_to_ddd ( latlon->lon );
285 case VIK_DEGREE_FORMAT_DMM:
286 *lat = convert_lat_dec_to_dmm ( latlon->lat );
287 *lon = convert_lon_dec_to_dmm ( latlon->lon );
289 case VIK_DEGREE_FORMAT_DMS:
290 *lat = convert_lat_dec_to_dms ( latlon->lat );
291 *lon = convert_lon_dec_to_dms ( latlon->lon );
293 case VIK_DEGREE_FORMAT_RAW:
294 *lat = g_strdup_printf ( "%.6f", latlon->lat );
295 *lon = g_strdup_printf ( "%.6f", latlon->lon );
298 g_critical("Houston, we've had a problem. format=%d", format);
301 *lat = convert_lat_dec_to_ddd ( latlon->lat );
302 *lon = convert_lon_dec_to_ddd ( latlon->lon );