73 lines
2.4 KiB
C++
73 lines
2.4 KiB
C++
/*
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EXAMPLE osmium_tiles
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Convert WGS84 longitude and latitude to Mercator coordinates and tile
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coordinates.
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DEMONSTRATES USE OF:
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* the Location and Coordinates classes
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* the Mercator projection function
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* the Tile class
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LICENSE
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The code in this example file is released into the Public Domain.
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*/
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#include <cstdlib> // for std::exit, std::atoi, std::atof
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#include <iostream> // for std::cout, std::cerr
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// The Location contains a longitude and latitude and is usually used inside
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// a node to store its location in the world.
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#include <osmium/osm/location.hpp>
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// Needed for the Mercator projection function. Osmium supports the Mercator
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// projection out of the box, or pretty much any projection using the Proj.4
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// library (with the osmium::geom::Projection class).
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#include <osmium/geom/mercator_projection.hpp>
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// The Tile class handles tile coordinates and zoom levels.
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#include <osmium/geom/tile.hpp>
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int main(int argc, char* argv[]) {
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if (argc != 4) {
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std::cerr << "Usage: " << argv[0] << " ZOOM LON LAT\n";
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std::exit(1);
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}
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const int zoom = std::atoi(argv[1]);
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if (zoom < 0 || zoom > 30) {
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std::cerr << "ERROR: Zoom must be between 0 and 30\n";
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std::exit(1);
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}
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const double lon = std::atof(argv[2]);
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const double lat = std::atof(argv[3]);
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// Create location from WGS84 coordinates. In Osmium the order of
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// coordinate values is always x/longitude first, then y/latitude.
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const osmium::Location location{lon, lat};
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std::cout << "WGS84: lon=" << lon << " lat=" << lat << "\n";
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// A location can store some invalid locations, ie locations outside the
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// -180 to 180 and -90 to 90 degree range. This function checks for that.
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if (!location.valid()) {
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std::cerr << "ERROR: Location is invalid\n";
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std::exit(1);
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}
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// Project the coordinates using a helper function. You can also use the
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// osmium::geom::MercatorProjection class.
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const osmium::geom::Coordinates c = osmium::geom::lonlat_to_mercator(location);
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std::cout << "Mercator: x=" << c.x << " y=" << c.y << "\n";
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// Create a tile at this location. This will also internally use the
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// Mercator projection and then calculate the tile coordinates.
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const osmium::geom::Tile tile{uint32_t(zoom), location};
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std::cout << "Tile: zoom=" << tile.z << " x=" << tile.x << " y=" << tile.y << "\n";
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}
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