199 lines
4.6 KiB
C++
199 lines
4.6 KiB
C++
/*
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* (c) 2002-2016 Hannes Krueger
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* This file is part of the GPLIGC/ogie package
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>
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*
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*/
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#include "projection.h"
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#include <string>
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#include <iostream>
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#include <cmath>
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#include <cstdlib>
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//const std::string rcsid_projection_cpp =
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// "$Id: projection.cpp 3 2014-07-31 09:59:20Z kruegerh $";
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//const std::string rcsid_projection_h = PROJECTION_H;
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Projection::Projection()
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{
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sphere_radius = 6371.0;
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// this is 1 in km on a great circle
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degree_dist = (2 * M_PI * sphere_radius) / 360.0;
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// this is the default
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projection = PROJ_PSEUDO_CYL_NO1;
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// 9999 is the "not set"-flag
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center_lat = 9999;
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center_lon = 9999;
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}
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void
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Projection::get_xy(float lat, float lon, float &x, float &y)
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{
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//std::cout << "ENTERING proj::get_xy" << std::flush;
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//std::cout << "ENTERING proj::get_xy" << center_lat << " " << center_lon << std::endl << std::flush;
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if (center_lat == 9999 || center_lon == 9999) {
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std::
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cerr << "Projection class: get_xy: center isn't set!"
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<< std::endl;
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return;
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}
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if (lat > 90)
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lat = 90;
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if (lat < -90)
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lat = -90;
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// This pseudo cylindrical projection has true lengths on meridians and latitude circles...
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if (projection == PROJ_PSEUDO_CYL_NO1) {
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float latdiff = center_lat - lat;
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float londiff = center_lon - lon;
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y = latdiff * degree_dist;
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x = londiff * degree_dist * cos((M_PI / 180.0) * lat);
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return;
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}
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// This cylindrical projection has true lengths on meridian only
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if (projection == PROJ_CYL_NO1) {
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y = (center_lat - lat) * degree_dist;
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x = (center_lon - lon) * degree_dist;
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return;
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}
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// platt(?) (Flaechentreu)
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if (projection == PROJ_CYL_PLATT) {
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float aequatdist_center =
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sin(center_lat * (M_PI / 180.0)) * sphere_radius;
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float aequatdist_point =
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sin(lat * (M_PI / 180.0)) * sphere_radius;
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y = aequatdist_center - aequatdist_point;
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x = (center_lon - lon) * degree_dist;
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return;
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}
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if (projection == PROJ_CYL_MERCATOR) {
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x = sphere_radius * (center_lon * (M_PI / 180.0) -
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lon * (M_PI / 180.0));
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//x = (center_lon - lon) * degree_dist;
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//std::cout << x << std::endl;
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float sign = 1.0;
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if (lat < 0)
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sign = -1.0;
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float aequatdist_point =
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-sign * sphere_radius *
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log(tan
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((M_PI / 4.0) +
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((fabs(lat) * (M_PI / 180.0)) / 2.0)));
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float sign_c = 1.0;
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if (center_lat < 0)
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sign_c = -1.0;
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float aequatdist_center =
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-sign_c * sphere_radius *
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log(tan
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((M_PI / 4.0) +
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((fabs(center_lat) * (M_PI / 180.0)) / 2.0)));
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y = -(aequatdist_center - aequatdist_point);
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return;
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}
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std::cerr << "No valid projection....." << std::endl;
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exit(1);
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}
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void Projection::get_latlon(float x, float y, float &lat, float &lon)
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{
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if (center_lat == 9999 || center_lon == 9999) {
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std::
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cerr <<
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"Projection class: get_latlon: center isn't set!" <<
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std::endl;
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return;
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}
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// this is 1 in km on a great circle
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degree_dist = (2 * M_PI * sphere_radius) / 360.0;
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if (projection == PROJ_PSEUDO_CYL_NO1) {
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lat = center_lat + (y / degree_dist);
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lon =
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center_lon +
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(x / (degree_dist * cos((M_PI / 180.0) * lat)));
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return;
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}
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if (projection == PROJ_CYL_NO1) {
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lat = center_lat + (y / degree_dist);
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lon = center_lon + (x / degree_dist);
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return;
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}
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if (projection == PROJ_CYL_PLATT) {
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lon = center_lon + (x / degree_dist);
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float aequatdist_center =
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sin(center_lat * (M_PI / 180.0)) * sphere_radius;
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lat =
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asin((y +
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aequatdist_center) / sphere_radius) / (M_PI /
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180.0);
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return;
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}
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if (projection == PROJ_CYL_MERCATOR) {
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lon = center_lon + (x / degree_dist);
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float sign_c = 1.0;
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if (center_lat < 0)
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sign_c = -1.0;
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float aequatdist_center =
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-sign_c * sphere_radius *
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log(tan
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((M_PI / 4.0) +
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((fabs(center_lat) * (M_PI / 180.0)) / 2.0)));
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float northing = aequatdist_center - y;
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lat =
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-(2.0 * atan(exp(northing / sphere_radius)) -
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(M_PI / 2.0)) / (M_PI / 180.0);
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return;
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}
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std::cerr << "No valid projection....." << std::endl;
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exit(1);
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}
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