def RasterToPoly(raster_file_path, out_vec_path, DelBG=False):
inraster = gdal.Open(raster_file_path) # 读取路径中的栅格数据
inband = inraster.GetRasterBand(1) # 这个波段就是最后想要转为矢量的波段，如果是单波段数据的话那就都是1
prj = osr.SpatialReference()
prj.ImportFromWkt(inraster.GetProjection()) # 读取栅格数据的投影信息，用来为后面生成的矢量做准备
raster_file = os.path.basename(raster_file_path)
raster_name, _ = os.path.splitext(raster_file)
shp_file_path = os.path.join(out_vec_path, raster_name + '.shp')
drv = ogr.GetDriverByName("ESRI Shapefile")
if os.path.exists(shp_file_path):
drv.DeleteDataSource(shp_file_path)
Polygon = drv.CreateDataSource(shp_file_path) # 创建一个目标文件
Poly_layer = Polygon.CreateLayer(
shp_file_path[:-4], srs=prj,
geom_type=ogr.wkbMultiPolygon) # 对shp文件创建一个图层，定义为多个面类
newField = ogr.FieldDefn(
'Value', ogr.OFTReal) # 给目标shp文件添加一个字段，用来存储原始栅格的pixel value
Poly_layer.CreateField(newField)
gdal.FPolygonize(inband, None, Poly_layer, 0,
['8CONNECTED=8']) # 核心函数，执行的就是栅格转矢量操作
Polygon.SyncToDisk()
Polygon = None
if DelBG:
deleteBackground(shp_file_path, 0) # 删除背景
def polygonize_1(is_int_polygonize=True):
src_ds = gdal.Open('data/polygonize_in.grd')
src_band = src_ds.GetRasterBand(1)
# Create a memory OGR datasource to put results in.
mem_drv = ogr.GetDriverByName('Memory')
mem_ds = mem_drv.CreateDataSource('out')
mem_layer = mem_ds.CreateLayer('poly', None, ogr.wkbPolygon)
fd = ogr.FieldDefn('DN', ogr.OFTInteger)
mem_layer.CreateField(fd)
# run the algorithm.
if is_int_polygonize:
result = gdal.Polygonize(src_band, src_band.GetMaskBand(), mem_layer,
0)
else:
result = gdal.FPolygonize(src_band, src_band.GetMaskBand(), mem_layer,
0)
if result != 0:
gdaltest.post_reason('Polygonize failed')
return 'fail'
# Confirm we get the set of expected features in the output layer.
expected_feature_number = 13
if mem_layer.GetFeatureCount() != expected_feature_number:
gdaltest.post_reason(
'GetFeatureCount() returned %d instead of %d' %
(mem_layer.GetFeatureCount(), expected_feature_number))
return 'fail'
expect = [107, 123, 115, 115, 140, 148, 123, 140, 156, 100, 101, 102, 103]
tr = ogrtest.check_features_against_list(mem_layer, 'DN', expect)
# check at least one geometry.
if tr:
mem_layer.SetAttributeFilter('dn = 156')
feat_read = mem_layer.GetNextFeature()
if ogrtest.check_feature_geometry(
feat_read,
'POLYGON ((440720 3751200,440720 3751020,440900 3751020,440900 3751200,440720 3751200),(440780 3751140,440840 3751140,440840 3751080,440780 3751080,440780 3751140))'
) != 0:
tr = 0
feat_read.Destroy()
if tr:
return 'success'
else:
return 'fail'
dst_layer.CreateField(fd)
dst_field = 0
else:
if dst_fieldname is not None:
dst_field = dst_layer.GetLayerDefn().GetFieldIndex(dst_fieldname)
if dst_field < 0:
print("Warning: cannot find field '%s' in layer '%s'" % (dst_fieldname, dst_layername))
# =============================================================================
# Invoke algorithm.
# =============================================================================
if quiet_flag:
prog_func = None
else:
prog_func = gdal.TermProgress_nocb
# result = None
if int_flag:
result = gdal.Polygonize(srcband, maskband, dst_layer, dst_field, options,
callback=prog_func)
else:
result = gdal.FPolygonize(srcband, maskband, dst_layer, dst_field, options,
callback=prog_func)
srcband = None
src_ds = None
dst_ds = None
mask_ds = None