NAME¶
gdal_polygonize - gdal_polygonize.py produces a polygon feature layer from a
raster
SYNOPSIS¶
gdal_polygonize.py [-8] [-nomask] [-mask filename] raster_file [-b band]
[-q] [-f ogr_format] out_file [layer] [fieldname]
DESCRIPTION¶
This utility creates vector polygons for all connected regions of pixels in the
raster sharing a common pixel value. Each polygon is created with an attribute
indicating the pixel value of that polygon. A raster mask may also be provided
to determine which pixels are eligible for processing.
The utility will create the output vector datasource if it does not already
exist, defaulting to GML format.
The utility is based on the GDALPolygonize() function which has additional
details on the algorithm.
- -8:
- (GDAL >= 1.10) Use 8 connectedness. Default is 4 connectedness.
- -nomask:
- Do not use the default validity mask for the input band (such as nodata,
or alpha masks).
- -mask filename:
- Use the first band of the specified file as a validity mask (zero is
invalid, non-zero is valid).
- raster_file
- The source raster file from which polygons are derived.
- -b band:
- The band on raster_file to build the polygons from.
- -f ogr_format
- Select the output format of the file to be created. Default is GML.
- out_file
- The destination vector file to which the polygons will be written.
- layer
- The name of the layer created to hold the polygon features.
- fieldname
- The name of the field to create (defaults to 'DN').
- -q:
- The script runs in quiet mode. The progress monitor is supressed and
routine messages are not displayed.
AUTHORS¶
Frank Warmerdam warmerdam@pobox.com