Python osgeo.gdal 模块，Polygonize() 实例源码

def createGeoJSONFromRaster(geoJsonFileName, array2d, geom, proj,
                            layerName="BuildingID",
                            fieldName="BuildingID"):

    memdrv = gdal.GetDriverByName('MEM')
    src_ds = memdrv.Create('', array2d.shape[1], array2d.shape[0], 1)
    src_ds.SetGeoTransform(geom)
    src_ds.SetProjection(proj)
    band = src_ds.GetRasterBand(1)
    band.WriteArray(array2d)

    dst_layername = "BuildingID"
    drv = ogr.GetDriverByName("geojson")
    dst_ds = drv.CreateDataSource(geoJsonFileName)
    dst_layer = dst_ds.CreateLayer(layerName, srs=None)

    fd = ogr.FieldDefn(fieldName, ogr.OFTInteger)
    dst_layer.CreateField(fd)
    dst_field = 1

    gdal.Polygonize(band, None, dst_layer, dst_field, [], callback=None)

    return

def polygonize(self,rasterTemp,outShp):

            sourceRaster = gdal.Open(rasterTemp)
            band = sourceRaster.GetRasterBand(1)
            driver = ogr.GetDriverByName("ESRI Shapefile")
            # If shapefile already exist, delete it
            if os.path.exists(outShp):
                driver.DeleteDataSource(outShp)

            outDatasource = driver.CreateDataSource(outShp)            
            # get proj from raster            
            srs = osr.SpatialReference()
            srs.ImportFromWkt( sourceRaster.GetProjectionRef() )
            # create layer with proj
            outLayer = outDatasource.CreateLayer(outShp,srs)
            # Add class column (1,2...) to shapefile

            newField = ogr.FieldDefn('Class', ogr.OFTInteger)
            outLayer.CreateField(newField)

            gdal.Polygonize(band, None,outLayer, 0,[],callback=None)  

            outDatasource.Destroy()
            sourceRaster=None
            band=None


            ioShpFile = ogr.Open(outShp, update = 1)


            lyr = ioShpFile.GetLayerByIndex(0)

            lyr.ResetReading()    

            for i in lyr:
                lyr.SetFeature(i)
            # if area is less than inMinSize or if it isn't forest, remove polygon 
                if i.GetField('Class')!=1:
                    lyr.DeleteFeature(i.GetFID())        
            ioShpFile.Destroy()

            return outShp