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| (Nejsou zobrazeny 3 mezilehlé verze od stejného uživatele.) |
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| Tato stránka obsahuje ukázku zdrojového textu demonstračního programu využívající pro přístup k vektorovým datům knihovnu '''[[GDAL/OGR|OGR]]'''. Program je inspirován skriptem z [[153GIS2 2009 - 10. cvičení#1|cvičení GIS2]].
| | {{freegiswiki|OGR / Ukázka použití}} |
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| __TOC__
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| == Vypsání atributů ==
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| === C++ ===
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| <source lang="cpp">
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| #include <iostream>
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| #include "ogrsf_frmts.h"
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| using std::cout;
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| using std::cerr;
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| using std::endl;
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| int main(int argc, char **argv)
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| {
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| const char *filename;
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|
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| OGRDataSource *poDS;
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| OGRLayer *poLayer;
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| OGRFeatureDefn *poFDefn;
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| if (argc != 2) {
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| cerr << "Pouziti: " << argv[0] << " shapefile" << endl;
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| return 1;
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| }
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|
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| filename = argv[1];
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|
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| // registrovat dostupne OGR ovladace
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| OGRRegisterAll();
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| // otevrit ShapeFile pro cteni
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| poDS = OGRSFDriverRegistrar::Open(filename, FALSE);
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| if (poDS == NULL) {
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| cerr << "Otevreni '" << filename << "' selhalo." << endl;
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| return 1;
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| }
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|
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| // nacist prvni OGR vrstvu (tj. Shapefile)
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| poLayer = poDS->GetLayer(0);
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| if (poLayer == NULL) {
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| cerr << "Nelze nacist OGR vrstvu." << endl;
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| return 1;
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| }
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| // ziskat informace o vrstve
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| poFDefn = poLayer->GetLayerDefn();
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| cout << "Detekovana OGR vrstva '" << poFDefn->GetName() << "'.\n\n";
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| for(int iField = 0; iField < poFDefn->GetFieldCount(); iField++) {
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| // ziskat informace o atributovem sloupci
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| OGRFieldDefn *poFieldDefn = poFDefn->GetFieldDefn(iField);
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| cout << poFieldDefn->GetNameRef() << endl;
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| }
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| return 0;
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| }
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| </source>
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| === Python ===
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| <source lang="python">
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| import sys
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| import osgeo.ogr as ogr
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| def main():
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| if len(sys.argv) != 2:
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| print >> sys.stderr, "Pouziti: %s shapefile" % sys.argv[0]
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| return 1
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|
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| filename = sys.argv[1]
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| # otevrit ShapeFile pro cteni
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| ds = ogr.Open(filename)
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| if ds is None:
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| print >> sys.stderr, "Otevreni '%s' selhalo." % filename
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| return 1
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| # nacist prvni OGR vrstvu (tj. Shapefile)
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| lyr = ds.GetLayer(0)
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| if lyr is None:
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| print >> sys.stderr, "Nelze nacist OGR vrstvu."
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|
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| # ziskat informace o vrstve
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| feat_defn = lyr.GetLayerDefn()
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| print "Detekovana OGR vrstva '%s'.\n" % feat_defn.GetName()
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| for i in range(feat_defn.GetFieldCount()):
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| # ziskat informace o atributovem sloupci
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| field_defn = feat_defn.GetFieldDefn(i)
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| print field_defn.GetNameRef()
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|
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| return 0
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| if __name__ == "__main__":
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| sys.exit(main())
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| </source>
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| == Prostorové predikáty ==
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| === C++ ===
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| <source lang=cpp>
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| #include <iostream>
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| #include <ctime>
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| #include "ogrsf_frmts.h"
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|
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| using std::cerr;
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| using std::endl;
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| using std::cout;
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|
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| OGRDataSource *open_dsn(const char *dsn)
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| {
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| OGRDataSource *poDs;
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|
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| poDs = OGRSFDriverRegistrar::Open(dsn, FALSE);
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| if (!poDs)
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| cerr << "Otevreni " << dsn << " selhalo." << std::endl;
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|
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| return poDs;
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| }
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|
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| int compute_number(OGRLayer *poLayer1, OGRLayer *poLayer2)
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| {
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| int count, i;
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| int nfeat;
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| bool found;
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|
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| OGRFeature *poFeat1, *poFeat2;
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| OGRGeometry *poGeom1, *poGeom2;
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|
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| count = 0;
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|
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| nfeat = poLayer1->GetFeatureCount();
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|
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| /* sekvencne cti prvky z vsrtvy 1 (body) */
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| poLayer1->ResetReading();
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| i = 0;
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| while(true) {
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| cerr << "\r" << i << "/" << nfeat;
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| poFeat1 = poLayer1->GetNextFeature();
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| if (!poFeat1)
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| break;
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| poGeom1 = poFeat1->GetGeometryRef();
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| if (!poGeom1 || poGeom1->getGeometryType() != wkbPoint)
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| continue;
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|
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| /* sekvencne cti prvky z vrstvy 2 (polygony) */
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| found = false;
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| poLayer2->ResetReading();
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| poLayer2->SetSpatialFilter(poGeom1);
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| while (!found) {
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| poFeat2 = poLayer2->GetNextFeature();
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| if (!poFeat2)
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| break;
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| poGeom2 = poFeat2->GetGeometryRef();
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| if (!poGeom2 || poGeom2->getGeometryType() != wkbPolygon)
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| continue;
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|
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| if (poGeom1->Within(poGeom2)) {
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| found = true;
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| }
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|
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| OGRFeature::DestroyFeature(poFeat2);
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| }
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| if (found)
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| count++;
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|
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| OGRFeature::DestroyFeature(poFeat1);
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| i++;
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| }
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| cerr << "\r";
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|
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| return count;
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| }
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|
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| int main(int argc, char **argv)
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| {
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| const char *dsn1, *dsn2, *relation;
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| const char *pszDriverName = "SQLite";
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| char **papszLCO;
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| time_t start;
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| OGRSFDriver *poDriver;
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| OGRDataSource *poDs1, *poDs2, *poDsSL;
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| OGRLayer *poLayer1, *poLayer2;
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|
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| if (argc != 3) {
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| cerr << "Pouziti: " << argv[0]
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| << " <bodova vrstva> <polygonova vrstva>" << endl;
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| return 1;
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| }
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|
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| dsn1 = argv[1];
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| dsn2 = argv[2];
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| relation = argv[3];
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|
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| // registrovat dostupne OGR ovladace
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| OGRRegisterAll();
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|
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| cout << "Nacitam data..." << endl;
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| // otevrit dsn1, dsn2 pro cteni
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| poDs1 = open_dsn(dsn1);
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| poDs2 = open_dsn(dsn2);
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| if (!poDs1 || !poDs2) {
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| return 1;
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| }
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|
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| // nacist prvni OGR vrstvu
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| poLayer1 = poDs1->GetLayer(0);
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| poLayer2 = poDs2->GetLayer(0);
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| if (!poLayer1 || !poLayer2 ) {
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| cerr << "Nelze nacist OGR vrstvu." << endl;
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| return 1;
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| }
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| // konverze dat do databaze SpatiaLite
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| cout << "Ukladam data do databaze SpatiaLite..." << endl;
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| poDriver = OGRSFDriverRegistrar::GetRegistrar()->GetDriverByName(pszDriverName);
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| if (!poDriver) {
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| cerr << "Driver " << pszDriverName << " neni dostupny" << endl;
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| return 1;
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| }
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| poDsSL = poDriver->Open("tmp.sqlite", TRUE);
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| if (!poDsSL) {
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| char **papszDSCO = NULL;
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| papszDSCO = CSLSetNameValue(papszDSCO, "SPATIALITE", "YES");
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| poDsSL = poDriver->CreateDataSource("tmp.sqlite", papszDSCO);
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| }
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| papszLCO = NULL;
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| papszLCO = CSLSetNameValue(papszLCO, "OVERWRITE", "YES");
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| poLayer1 = poDsSL->CopyLayer(poLayer1, "points", papszLCO);
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| poLayer2 = poDsSL->CopyLayer(poLayer2, "polygons", papszLCO);
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| cout << "Analyzuji data..." << endl;
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| start = time(NULL);
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| cout << "Pocet bodu: " << compute_number(poLayer1, poLayer2)
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| << "/" << poLayer1->GetFeatureCount() << endl;
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| cout << "Cas vypoctu: " << time(NULL) - start << " sec" << endl;
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| OGRDataSource::DestroyDataSource(poDsSL);
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| OGRDataSource::DestroyDataSource(poDs1);
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| OGRDataSource::DestroyDataSource(poDs2);
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| return 0;
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| }
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| </source>
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| == Související články ==
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| * [[Programování s knihovnou GDAL]]
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| * [[153GIS2 - 10. cvičení - GRASS GIS|Ukázka skriptů pro GRASS GIS]]
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| == Externí odkazy ==
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| * [http://gdal.osgeo.org/ogr/hierarchy.html OGR API]
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| * [http://gdal.osgeo.org/ogr/ogr_apitut.html OGR API Tutorial]
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| * [http://gdal.osgeo.org/ogr/ogr_arch.html OGR Architecture]
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| * [http://grass.fsv.cvut.cz/gwiki/V%C3%BDm%C4%9Bnn%C3%BD_form%C3%A1t_ISKN#Python Ukázka skriptu pro zpracování katastrálních dat ve formátu VFK]
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| {{GFOSS}}
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| {{Programování}}
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| {{C++}}
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| {{Python}}
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