使用GDAL/OGR讀寫矢量文件
- 2019 年 10 月 10 日
- 筆記
感覺GIS中矢量相關內容還是挺龐雜的，並且由於版本迭代的關係，使用GDAL/OGR讀寫矢量的資料也有點不太一樣。這裡總結了一個讀寫矢量的示例，實現程式碼如下：
#include <iostream> #include <gdal/ogrsf_frmts.h> using namespace std; bool ReadDXF(string filePath, vector<vector<OGRPoint>>& vertexPoint) { GDALDataset *poDS = (GDALDataset*)GDALOpenEx(filePath.c_str(), GDAL_OF_VECTOR, NULL, NULL, NULL); if (!poDS) { printf("無法讀取該文件，試檢查格式是否正確！"); return false; } if (poDS->GetLayerCount()<1) { printf("該文件的層數小於1，試檢查格式是否正確！"); return false; } OGRLayer *poLayer = poDS->GetLayer(0); //讀取層 poLayer->ResetReading(); OGRFeature *poFeature; while ((poFeature = poLayer->GetNextFeature()) != NULL) { OGRGeometry *pGeo = poFeature->GetGeometryRef(); OGRwkbGeometryType pGeoType = pGeo->getGeometryType(); if (pGeoType == wkbLineString || pGeoType == wkbLineString25D) { OGRLinearRing *pCurve = (OGRLinearRing*)pGeo; if (pCurve->getNumPoints() < 1) { continue; } vector<OGRPoint> pl; for (int i = 0; i<pCurve->getNumPoints(); i++) { OGRPoint point; pCurve->getPoint(i, &point); pl.push_back(point); } vertexPoint.push_back(pl); } //// //OGRFeatureDefn *poFDefn = poLayer->GetLayerDefn(); //int n = poFDefn->GetFieldCount(); //獲得欄位的數目，不包括前兩個欄位（FID,Shape); //for (int iField = 0; iField <n; iField++) //{ // //輸出每個欄位的值 // cout << poFeature->GetFieldAsString(iField) << " "; //} //cout << endl; OGRFeature::DestroyFeature(poFeature); } GDALClose(poDS); poDS = nullptr; return true; } bool WriteShp(string filePath, vector<vector<OGRPoint>> vertexPoint) { //創建 GDALDriver* driver = GetGDALDriverManager()->GetDriverByName("ESRI Shapefile"); if (!driver) { printf("Get Driver ESRI Shapefile Error！n"); return false; } GDALDataset* dataset = driver->Create(filePath.c_str(), 0, 0, 0, GDT_Unknown, NULL); OGRLayer* poLayer = dataset->CreateLayer("houseType", NULL, wkbPolygon, NULL); //創建屬性欄位 { // 字元串 OGRFieldDefn oField1("名稱", OFTString); oField1.SetWidth(8); if (poLayer->CreateField(&oField1) != OGRERR_NONE) { printf("Creating Name field failed.n"); return FALSE; } // 浮點數 OGRFieldDefn oField2("面積", OFTReal); oField2.SetPrecision(3); if (poLayer->CreateField(&oField2) != OGRERR_NONE) { printf("Creating Name field failed.n"); return FALSE; } // 整型 OGRFieldDefn oField3("結點數", OFTInteger); if (poLayer->CreateField(&oField3) != OGRERR_NONE) { printf("Creating Name field failed.n"); return FALSE; } } //創建特徵 for (auto& iter : vertexPoint) { OGRFeature *poFeature = new OGRFeature(poLayer->GetLayerDefn()); OGRLinearRing ogrring; int pNum = (int)iter.size(); ogrring.setNumPoints(pNum); for (int i = 0; i < iter.size(); i++) { ogrring.setPoint(i, iter[i].getX(), iter[i].getY(), iter[i].getZ()); //cout << iter[i].x() << 't' << iter[i].y() << 't' << iter[i].z() << endl; } //cout << "-----------------------------n"; OGRPolygon polygon; polygon.addRing(&ogrring); poFeature->SetGeometry(&polygon); poFeature->SetField("名稱", "多邊形"); poFeature->SetField("面積", polygon.get_Area()); poFeature->SetField("結點數", pNum); if (poLayer->CreateFeature(poFeature) != OGRERR_NONE) { printf("Failed to create feature in shapefile.n"); return false; } } //釋放 GDALClose(dataset); dataset = nullptr; //GDALDestroyDriverManager(); return true; } int main() { GDALAllRegister(); CPLSetConfigOption("GDAL_FILENAME_IS_UTF8", "NO"); //支援中文路徑 CPLSetConfigOption("SHAPE_ENCODING", ""); //解決中文亂碼問題 string filePath = "D:/2.dxf"; vector<vector<OGRPoint>> vertexPoint; if (!ReadDXF(filePath, vertexPoint)) { return 1; } string newPath = "C:/Users/charlee/Desktop/SHP/dst.shp"; WriteShp(newPath, vertexPoint); return 0; }在這個示例中，讀取一個DXF文件中的線（環）特徵，將其轉換成面，然後保存在一個SHP中。同時，還給該SHP文件寫入了相應的屬性欄位。
讀取的DXF文件：
創建並保存的SHP文件：
