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 process(self, input_filename, output_filename, geo_reference=None, generate_metadata=True, merge_with=None, original_footprint=None): # open the dataset and create an In-Memory Dataset as copy # to perform optimizations ds = create_mem_copy(gdal.Open(input_filename)) gt = ds.GetGeoTransform() footprint_wkt = None if not geo_reference: if gt == (0.0, 1.0, 0.0, 0.0, 0.0, 1.0): if ds.GetGCPCount() > 0: geo_reference = InternalGCPs() else: raise ValueError("No geospatial reference for " "unreferenced dataset given.") if geo_reference: logger.debug("Applying geo reference '%s'." % type(geo_reference).__name__) # footprint is always in EPSG:4326 ds, footprint_wkt = geo_reference.apply(ds) # apply optimizations for optimization in self.get_optimizations(ds): logger.debug("Applying optimization '%s'." % type(optimization).__name__) try: new_ds = optimization(ds) if new_ds is not ds: # cleanup afterwards cleanup_temp(ds) ds = new_ds except: cleanup_temp(ds) raise # generate the footprint from the dataset if not footprint_wkt: logger.debug("Generating footprint.") footprint_wkt = self._generate_footprint_wkt(ds) # check that footprint is inside of extent of generated image # regenerate otherwise else: tmp_extent = getExtentFromRectifiedDS(ds) tmp_bbox = Polygon.from_bbox( (tmp_extent[0], tmp_extent[1], tmp_extent[2], tmp_extent[3])) # transform image bbox to EPSG:4326 if necessary proj = ds.GetProjection() srs = osr.SpatialReference() try: srs.ImportFromWkt(proj) srs.AutoIdentifyEPSG() ptype = "PROJCS" if srs.IsProjected() else "GEOGCS" srid = int(srs.GetAuthorityCode(ptype)) if srid != '4326': out_srs = osr.SpatialReference() out_srs.ImportFromEPSG(4326) transform = osr.CoordinateTransformation(srs, out_srs) tmp_bbox2 = ogr.CreateGeometryFromWkt(tmp_bbox.wkt) tmp_bbox2.Transform(transform) tmp_bbox = GEOSGeometry(tmp_bbox2.ExportToWkt()) except (RuntimeError, TypeError), e: logger.warn("Projection: %s" % proj) logger.warn("Failed to identify projection's EPSG code." "%s: %s" % (type(e).__name__, str(e))) tmp_footprint = GEOSGeometry(footprint_wkt) if not tmp_bbox.contains(tmp_footprint): logger.debug("Re-generating footprint because not inside of " "generated image.") footprint_wkt = tmp_footprint.intersection(tmp_bbox).wkt
def _generate_footprint_wkt(self, ds): """ Generate a footprint 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 = numpy.zeros((ds.RasterYSize, ds.RasterXSize), dtype=numpy.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 tmp_ds = create_mem(ds.RasterXSize + 2, ds.RasterYSize + 2, 1, gdal.GDT_Byte) copy_projection(ds, tmp_ds) tmp_band = tmp_ds.GetRasterBand(1) tmp_band.WriteArray(nodata_map.astype(numpy.uint8)) # Remove unwanted small areas of nodata # www.gdal.org/gdal__alg_8h.html#a33309c0a316b223bd33ae5753cc7f616 no_pixels = tmp_ds.RasterXSize * tmp_ds.RasterYSize threshold = 4 max_threshold = (no_pixels / 16) if self.sieve_max_threshold > 0: max_threshold = self.sieve_max_threshold while threshold <= max_threshold and threshold < 2147483647: gdal.SieveFilter(tmp_band, None, tmp_band, threshold, 4) threshold *= 4 #for debugging: #gdal.GetDriverByName('GTiff').CreateCopy('/tmp/test.tif', tmp_ds) # 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, 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) tmp_ds = None if layer.GetFeatureCount() > 1: # if there is more than one polygon, compute the minimum # bounding polygon logger.debug("Merging %s features in footprint." % layer.GetFeatureCount()) # union all features in one multi-polygon geometry = ogr.Geometry(ogr.wkbMultiPolygon) while True: feature = layer.GetNextFeature() if not feature: break geometry.AddGeometry(feature.GetGeometryRef()) geometry = geometry.UnionCascaded() # TODO: improve this for a better minimum bounding polygon geometry = geometry.ConvexHull() elif layer.GetFeatureCount() < 1: # there was an error during polygonization raise RuntimeError("Error during polygonization. No feature " "obtained.") else: # obtain geometry from the first (and only) layer feature = layer.GetNextFeature() geometry = feature.GetGeometryRef() if geometry.GetGeometryType() != ogr.wkbPolygon: raise RuntimeError( "Error during polygonization. Wrong geometry " "type: %s" % ogr.GeometryTypeToName(geometry.GetGeometryType())) # check if reprojection to latlon is necessary if not sr.IsGeographic(): dst_sr = osr.SpatialReference() dst_sr.ImportFromEPSG(4326) try: geometry.TransformTo(dst_sr) except RuntimeError: geometry.Transform(osr.CoordinateTransformation(sr, dst_sr)) gt = ds.GetGeoTransform() resolution = min(abs(gt[1]), abs(gt[5])) simplification_value = self.simplification_factor * resolution #for debugging: #geometry.GetGeometryRef(0).GetPointCount() # 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 __init__(self, src, dst): self.fwd = osr.CoordinateTransformation(src, dst) self.bwd = osr.CoordinateTransformation(dst, src)