def __init__(self, dataset, wkt, srid=None, temporary_directory=None):
super(GDALGeometryMaskMergeSource, self).__init__(dataset)
srs = None
srid = 4326
if srid is not None:
srs = osr.SpatialReference()
srs.ImportFromEPSG(srid)
# create a geometry from the given WKT
#geom = ogr.CreateGeometryFromWkt(wkt)
# create an in-memory datasource and add one single layer
ogr_mem_driver = ogr.GetDriverByName("Memory")
data_source = ogr_mem_driver.CreateDataSource("xxx")
layer = data_source.CreateLayer("poly", srs)
# create a single feature and add the given geometry
feature = ogr.Feature(layer.GetLayerDefn())
feature.SetGeometryDirectly(ogr.Geometry(wkt=str(wkt)))
layer.CreateFeature(feature)
temporary_ds = temporary_dataset(
self.dataset.RasterXSize, self.dataset.RasterYSize, 1,
temp_root=temporary_directory
)
# create a temporary raster dataset with the exact same size as the
# dataset to be masked
with temporary_ds as mask_dataset:
band = mask_dataset.GetRasterBand(1)
band.Fill(1)
mask_dataset.SetGeoTransform(self.dataset.GetGeoTransform())
mask_dataset.SetProjection(self.dataset.GetProjection())
# finally rasterize the vector layer to the mask dataset
gdal.RasterizeLayer(mask_dataset, (1,), layer, burn_values=(0,))
source_mask_band = mask_dataset.GetRasterBand(1)
self.dataset.CreateMaskBand(gdal.GMF_PER_DATASET)
band = self.dataset.GetRasterBand(1)
mask_band = band.GetMaskBand()
block_x_size, block_y_size = source_mask_band.GetBlockSize()
num_x = source_mask_band.XSize / block_x_size
num_y = source_mask_band.YSize / block_y_size
for x, y in product(range(num_x), range(num_y)):
mask_band.WriteArray(
source_mask_band.ReadAsArray(
x*block_x_size, y*block_y_size,
block_x_size, block_y_size
),
x*block_x_size, y*block_y_size
)
def __init__(self, dataset, wkt, srid=None, temporary_directory=None):
super(GDALGeometryMaskMergeSource, self).__init__(dataset)
srs = None
srid = 4326
if srid is not None:
srs = osr.SpatialReference()
srs.ImportFromEPSG(srid)
# create a geometry from the given WKT
#geom = ogr.CreateGeometryFromWkt(wkt)
# create an in-memory datasource and add one single layer
ogr_mem_driver = ogr.GetDriverByName("Memory")
data_source = ogr_mem_driver.CreateDataSource("xxx")
layer = data_source.CreateLayer("poly", srs)
# create a single feature and add the given geometry
feature = ogr.Feature(layer.GetLayerDefn())
feature.SetGeometryDirectly(ogr.Geometry(wkt=str(wkt)))
layer.CreateFeature(feature)
temporary_ds = temporary_dataset(self.dataset.RasterXSize,
self.dataset.RasterYSize,
1,
temp_root=temporary_directory)
# create a temporary raster dataset with the exact same size as the
# dataset to be masked
with temporary_ds as mask_dataset:
band = mask_dataset.GetRasterBand(1)
band.Fill(1)
mask_dataset.SetGeoTransform(self.dataset.GetGeoTransform())
mask_dataset.SetProjection(self.dataset.GetProjection())
# finally rasterize the vector layer to the mask dataset
gdal.RasterizeLayer(mask_dataset, (1, ), layer, burn_values=(0, ))
source_mask_band = mask_dataset.GetRasterBand(1)
self.dataset.CreateMaskBand(gdal.GMF_PER_DATASET)
band = self.dataset.GetRasterBand(1)
mask_band = band.GetMaskBand()
block_x_size, block_y_size = source_mask_band.GetBlockSize()
num_x = source_mask_band.XSize / block_x_size
num_y = source_mask_band.YSize / block_y_size
for x, y in product(range(num_x), range(num_y)):
mask_band.WriteArray(
source_mask_band.ReadAsArray(x * block_x_size,
y * block_y_size,
block_x_size, block_y_size),
x * block_x_size, y * block_y_size)
def generate_footprint_wkt(ds, simplification_factor=2):
""" Generate a fooptrint from a raster, using black/no-data as exclusion
"""
# create an empty boolean array initialized as 'False' to store where
# values exist as a mask array.
nodata_map = np.zeros((ds.RasterYSize, ds.RasterXSize), dtype=np.bool)
for idx in range(1, ds.RasterCount + 1):
band = ds.GetRasterBand(idx)
raster_data = band.ReadAsArray()
nodata = band.GetNoDataValue()
if nodata is None:
nodata = 0
# apply the output to the map
nodata_map |= (raster_data != nodata)
# create a temporary in-memory dataset and write the nodata mask
# into its single band
with temporary_dataset(ds.RasterXSize + 2, ds.RasterYSize + 2, 1,
gdal.GDT_Byte) as tmp_ds:
copy_projection(ds, tmp_ds)
tmp_band = tmp_ds.GetRasterBand(1)
tmp_band.WriteArray(nodata_map.astype(np.uint8))
# create an OGR in memory layer to hold the created polygon
sr = osr.SpatialReference()
sr.ImportFromWkt(ds.GetProjectionRef())
ogr_ds = ogr.GetDriverByName('Memory').CreateDataSource('out')
layer = ogr_ds.CreateLayer('poly', sr.sr, ogr.wkbPolygon)
fd = ogr.FieldDefn('DN', ogr.OFTInteger)
layer.CreateField(fd)
# polygonize the mask band and store the result in the OGR layer
gdal.Polygonize(tmp_band, tmp_band, layer, 0)
if layer.GetFeatureCount() != 1:
# if there is more than one polygon, compute the minimum bounding polygon
geometry = ogr.Geometry(ogr.wkbPolygon)
while True:
feature = layer.GetNextFeature()
if not feature:
break
geometry = geometry.Union(feature.GetGeometryRef())
# TODO: improve this for a better minimum bounding polygon
geometry = geometry.ConvexHull()
else:
# obtain geometry from the first (and only) layer
feature = layer.GetNextFeature()
geometry = feature.GetGeometryRef()
if geometry.GetGeometryType() not in (ogr.wkbPolygon, ogr.wkbMultiPolygon):
raise RuntimeError("Error during poligonization. Wrong geometry "
"type.")
# check if reprojection to latlon is necessary
if not sr.IsGeographic():
dst_sr = osr.SpatialReference()
dst_sr.ImportFromEPSG(4326)
try:
geometry.TransformTo(dst_sr.sr)
except RuntimeError:
geometry.Transform(osr.CoordinateTransformation(sr.sr, dst_sr.sr))
gt = ds.GetGeoTransform()
resolution = min(abs(gt[1]), abs(gt[5]))
simplification_value = simplification_factor * resolution
# simplify the polygon. the tolerance value is *really* vague
try:
# SimplifyPreserveTopology() available since OGR 1.9.0
geometry = geometry.SimplifyPreserveTopology(simplification_value)
except AttributeError:
# use GeoDjango bindings if OGR is too old
geometry = ogr.CreateGeometryFromWkt(
GEOSGeometry(geometry.ExportToWkt()).simplify(
simplification_value, True).wkt)
return geometry.ExportToWkt()
def generate_footprint_wkt(ds, simplification_factor=2):
""" Generate a fooptrint from a raster, using black/no-data as exclusion
"""
# create an empty boolean array initialized as 'False' to store where
# values exist as a mask array.
nodata_map = np.zeros((ds.RasterYSize, ds.RasterXSize), dtype=np.bool)
for idx in range(1, ds.RasterCount + 1):
band = ds.GetRasterBand(idx)
raster_data = band.ReadAsArray()
nodata = band.GetNoDataValue()
if nodata is None:
nodata = 0
# apply the output to the map
nodata_map |= (raster_data != nodata)
# create a temporary in-memory dataset and write the nodata mask
# into its single band
with temporary_dataset(ds.RasterXSize + 2, ds.RasterYSize + 2, 1,
gdal.GDT_Byte) as tmp_ds:
copy_projection(ds, tmp_ds)
tmp_band = tmp_ds.GetRasterBand(1)
tmp_band.WriteArray(nodata_map.astype(np.uint8))
# create an OGR in memory layer to hold the created polygon
sr = osr.SpatialReference()
sr.ImportFromWkt(ds.GetProjectionRef())
ogr_ds = ogr.GetDriverByName('Memory').CreateDataSource('out')
layer = ogr_ds.CreateLayer('poly', sr.sr, ogr.wkbPolygon)
fd = ogr.FieldDefn('DN', ogr.OFTInteger)
layer.CreateField(fd)
# polygonize the mask band and store the result in the OGR layer
gdal.Polygonize(tmp_band, tmp_band, layer, 0)
if layer.GetFeatureCount() != 1:
# if there is more than one polygon, compute the minimum bounding polygon
geometry = ogr.Geometry(ogr.wkbPolygon)
while True:
feature = layer.GetNextFeature()
if not feature:
break
geometry = geometry.Union(feature.GetGeometryRef())
# TODO: improve this for a better minimum bounding polygon
geometry = geometry.ConvexHull()
else:
# obtain geometry from the first (and only) layer
feature = layer.GetNextFeature()
geometry = feature.GetGeometryRef()
if geometry.GetGeometryType() not in (ogr.wkbPolygon, ogr.wkbMultiPolygon):
raise RuntimeError("Error during poligonization. Wrong geometry "
"type.")
# check if reprojection to latlon is necessary
if not sr.IsGeographic():
dst_sr = osr.SpatialReference()
dst_sr.ImportFromEPSG(4326)
try:
geometry.TransformTo(dst_sr.sr)
except RuntimeError:
geometry.Transform(osr.CoordinateTransformation(sr.sr, dst_sr.sr))
gt = ds.GetGeoTransform()
resolution = min(abs(gt[1]), abs(gt[5]))
simplification_value = simplification_factor * resolution
# simplify the polygon. the tolerance value is *really* vague
try:
# SimplifyPreserveTopology() available since OGR 1.9.0
geometry = geometry.SimplifyPreserveTopology(simplification_value)
except AttributeError:
# use GeoDjango bindings if OGR is too old
geometry = ogr.CreateGeometryFromWkt(
GEOSGeometry(
geometry.ExportToWkt()
).simplify(simplification_value, True).wkt
)
return geometry.ExportToWkt()
