GIS中的矢量(Vector)包括点(point)、线(polyline)和多边形(polygon)。 在本例中,我们要进行矢量化的地理特征有: 山顶(点) 河流(多段线) 湖泊(多边形) 通过GeoPackage来创建一个空间数据库(spatial database),使得上述不同类型的矢量数据保存在同一个文件中。 Digitize Peaks 创建一个新的GeoPackage Layer。选择La...
首先,使用 菜单栏→Web→OpenLayer Plugin→ OpenStreetMap,将 OSM 底图添加到 QGIS 工作区中。视乎网速,载入的速度可能会有差异。然后,通过 菜单栏→Panel→OSM place search 打开地点搜索面板,输入 Manhattan。等下方列表出现后,点按 Zoom 来缩放到所选目标区域。 图4 可以发现,地图的形状并不符合实际情况。这...
QgsMapLayerRegistry::instance()->addMapLayer(layerTemp,true,true); //设置该图层的单一渲染风格 QgsSymbolV2* symbol = QgsSymbolV2::defaultSymbol(layerTemp->geometryType());//QGis::GeometryType::Polygon symbol->setColor(QColor(100,100,160,255)); layerTemp->setRendererV2( new QgsSingleSymbolRe...
“Day trajectories from point layer” is covered by the new“Split trajectories at time intervals”which supports splitting by hour, day, month, and year. “Clip trajectories by extent”still exists but, additionally, we can now also“Clip trajectories by polygon layer” There are two new event...
Go to Layer ‣ Add Vector Layer. Browse to the downloaded ne_10m_admin_0_countries.zip file and click Open. Select the ne_10m_admin_0_countries.shp as the layer in the Select layers to add… dialog. Click on Vector ‣ Analysis Tools ‣ Point in Polygon In the pop-up window,...
完整参数列表见QgsVectorLayer文档 第二种参数使用QgsDataSourceUri，代码如下 void MainWindow::addWfs...
But since I do not really need the ridgeline as a geometry with duplicate attributes, I wonder if I can add a symbol to the polygon layer that represents the ridgeline. Not sure how to go about this using the geometry of the layer to calculate the center line of the polygon to create ...
defprocessAlgorithm(self, progress):layer =QGisLayers.getObjectFromUri(self.getParameterValue(self.INPUT)) interval = self.getParameterValue(self.INTERVAL) isPolygon = layer.geometryType() == QGis.Polygon writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(layer.pendingFields(), ...
Re: [QGIS-Developer] Fwd: [Qgis-user] Editing a multipolygon object changes type from Multipolygon to Polygon I'll just add that I have observed the same behaviour using aGeoPackage based layer. It was during a teaching session with 10-15students, so I can't remember exactly how and ...
2、创建图层 (矢量图层类:QgsVectorLayer)(栅格图层类:QgsRasterLayer) QString path = "multiPoint?"; // 几何类型,"point", "linestring", "polygon", "multipoint","multilinestring","multipolygon" path.append( QString( "crs=EPSG:4326&")); //参照坐标系 ...