gdal_polygonize.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# ******************************************************************************
#  $Id$
#
#  Project:  GDAL Python Interface
#  Purpose:  Application for converting raster data to a vector polygon layer.
#  Author:   Frank Warmerdam, warmerdam@pobox.com
#
# ******************************************************************************
#  Copyright (c) 2008, Frank Warmerdam
#  Copyright (c) 2009-2013, Even Rouault <even dot rouault at spatialys.com>
#
#  Permission is hereby granted, free of charge, to any person obtaining a
#  copy of this software and associated documentation files (the "Software"),
#  to deal in the Software without restriction, including without limitation
#  the rights to use, copy, modify, merge, publish, distribute, sublicense,
#  and/or sell copies of the Software, and to permit persons to whom the
#  Software is furnished to do so, subject to the following conditions:
#
#  The above copyright notice and this permission notice shall be included
#  in all copies or substantial portions of the Software.
#
#  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
#  OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
#  THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
#  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
#  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
#  DEALINGS IN THE SOFTWARE.
# ******************************************************************************

import os.path
import sys

from osgeo import gdal
from osgeo import ogr


def Usage():
    print("""
gdal_polygonize [-8] [-nomask] [-mask filename] raster_file [-b band|mask]
                [-q] [-f ogr_format] out_file [layer] [fieldname]
""")
    sys.exit(1)


def DoesDriverHandleExtension(drv, ext):
    exts = drv.GetMetadataItem(gdal.DMD_EXTENSIONS)
    return exts is not None and exts.lower().find(ext.lower()) >= 0


def GetExtension(filename):
    ext = os.path.splitext(filename)[1]
    if ext.startswith('.'):
        ext = ext[1:]
    return ext


def GetOutputDriversFor(filename):
    drv_list = []
    ext = GetExtension(filename)
    for i in range(gdal.GetDriverCount()):
        drv = gdal.GetDriver(i)
        if (drv.GetMetadataItem(gdal.DCAP_CREATE) is not None or
            drv.GetMetadataItem(gdal.DCAP_CREATECOPY) is not None) and \
           drv.GetMetadataItem(gdal.DCAP_VECTOR) is not None:
            if ext and DoesDriverHandleExtension(drv, ext):
                drv_list.append(drv.ShortName)
            else:
                prefix = drv.GetMetadataItem(gdal.DMD_CONNECTION_PREFIX)
                if prefix is not None and filename.lower().startswith(prefix.lower()):
                    drv_list.append(drv.ShortName)

    return drv_list


def GetOutputDriverFor(filename):
    drv_list = GetOutputDriversFor(filename)
    ext = GetExtension(filename)
    if not drv_list:
        if not ext:
            return 'ESRI Shapefile'
        else:
            raise Exception("Cannot guess driver for %s" % filename)
    elif len(drv_list) > 1:
        print("Several drivers matching %s extension. Using %s" % (ext if ext else '', drv_list[0]))
    return drv_list[0]

# =============================================================================
# 	Mainline
# =============================================================================


frmt = None
options = []
quiet_flag = 0
src_filename = None
src_band_n = 1

dst_filename = None
dst_layername = None
dst_fieldname = None
dst_field = -1

mask = 'default'

gdal.AllRegister()
argv = gdal.GeneralCmdLineProcessor(sys.argv)
if argv is None:
    sys.exit(0)

# Parse command line arguments.
i = 1
while i < len(argv):
    arg = argv[i]

    if arg == '-f' or arg == '-of':
        i = i + 1
        frmt = argv[i]

    elif arg == '-q' or arg == '-quiet':
        quiet_flag = 1

    elif arg == '-8':
        options.append('8CONNECTED=8')

    elif arg == '-nomask':
        mask = 'none'

    elif arg == '-mask':
        i = i + 1
        mask = argv[i]

    elif arg == '-b':
        i = i + 1
        if argv[i].startswith('mask'):
            src_band_n = argv[i]
        else:
            src_band_n = int(argv[i])

    elif src_filename is None:
        src_filename = argv[i]

    elif dst_filename is None:
        dst_filename = argv[i]

    elif dst_layername is None:
        dst_layername = argv[i]

    elif dst_fieldname is None:
        dst_fieldname = argv[i]

    else:
        Usage()

    i = i + 1

if src_filename is None or dst_filename is None:
    Usage()

if frmt is None:
    frmt = GetOutputDriverFor(dst_filename)

if dst_layername is None:
    dst_layername = 'out'

# =============================================================================
# 	Verify we have next gen bindings with the polygonize method.
# =============================================================================
try:
    gdal.Polygonize
except AttributeError:
    print('')
    print('gdal.Polygonize() not available.  You are likely using "old gen"')
    print('bindings or an older version of the next gen bindings.')
    print('')
    sys.exit(1)

# =============================================================================
# Open source file
# =============================================================================

src_ds = gdal.Open(src_filename)

if src_ds is None:
    print('Unable to open %s' % src_filename)
    sys.exit(1)

if src_band_n == 'mask':
    srcband = src_ds.GetRasterBand(1).GetMaskBand()
    # Workaround the fact that most source bands have no dataset attached
    options.append('DATASET_FOR_GEOREF=' + src_filename)
elif isinstance(src_band_n, str) and src_band_n.startswith('mask,'):
    srcband = src_ds.GetRasterBand(int(src_band_n[len('mask,'):])).GetMaskBand()
    # Workaround the fact that most source bands have no dataset attached
    options.append('DATASET_FOR_GEOREF=' + src_filename)
else:
    srcband = src_ds.GetRasterBand(src_band_n)

if mask == 'default':
    maskband = srcband.GetMaskBand()
elif mask == 'none':
    maskband = None
else:
    mask_ds = gdal.Open(mask)
    maskband = mask_ds.GetRasterBand(1)

# =============================================================================
#       Try opening the destination file as an existing file.
# =============================================================================

try:
    gdal.PushErrorHandler('CPLQuietErrorHandler')
    dst_ds = ogr.Open(dst_filename, update=1)
    gdal.PopErrorHandler()
except:
    dst_ds = None

# =============================================================================
# 	Create output file.
# =============================================================================
if dst_ds is None:
    drv = ogr.GetDriverByName(frmt)
    if not quiet_flag:
        print('Creating output %s of format %s.' % (dst_filename, frmt))
    dst_ds = drv.CreateDataSource(dst_filename)

# =============================================================================
#       Find or create destination layer.
# =============================================================================
try:
    dst_layer = dst_ds.GetLayerByName(dst_layername)
except:
    dst_layer = None

if dst_layer is None:

    srs = src_ds.GetSpatialRef()
    dst_layer = dst_ds.CreateLayer(dst_layername, geom_type=ogr.wkbPolygon, srs=srs)

    if dst_fieldname is None:
        dst_fieldname = 'DN'

    fd = ogr.FieldDefn(dst_fieldname, ogr.OFTInteger)
    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 = gdal.Polygonize(srcband, maskband, dst_layer, dst_field, options,
                         callback=prog_func)

srcband = None
src_ds = None
dst_ds = None
mask_ds = None