function_historical_map.py 文件源码

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