gdallocationinfo (1) - Linux Man Pages
gdallocationinfo - gdallocationinfo raster query tool
Usage: gdallocationinfo [--help-general] [-xml] [-lifonly] [-valonly] [-b band]* [-overview overview_level] [-l_srs srs_def] [-geoloc] [-wgs84] srcfile [x y]
The gdallocationinfo utility provide a mechanism to query information about a pixel given it's location in one of a variety of coordinate systems. Several reporting options are provided.
- The output report will be XML formatted for convenient post processing.
- The only output is filenames production from the LocationInfo request against the database (ie. for identifying impacted file from VRT).
- The only output is the pixel values of the selected pixel on each of the selected bands.
- -b band:
- Selects a band to query. Multiple bands can be listed. By default all bands are queried.
- -overview overview_level:
- Query the (overview_level)th overview (overview_level=1 is the 1st overview), instead of the base band. Note that the x,y location (if the coordinate system is pixel/line) must still be given with respect to the base band.
- -l_srs srs def:
- The coordinate system of the input x, y location.
- Indicates input x,y points are in the georeferencing system of the image.
- Indicates input x,y points are WGS84 long, lat.
- The source GDAL raster datasource name.
- X location of target pixel. By default the coordinate system is pixel/line unless -l_srs, -wgs84 or -geoloc supplied.
- Y location of target pixel. By default the coordinate system is pixel/line unless -l_srs, -wgs84 or -geoloc supplied.
This utility is intended to provide a variety of information about a pixel. Currently it reports three things:
- The location of the pixel in pixel/line space.
- The result of a LocationInfo metadata query against the datasource - currently this is only implemented for VRT files which will report the file(s) used to satisfy requests for that pixel.
- The raster pixel value of that pixel for all or a subset of the bands.
- The unscaled pixel value if a Scale and/or Offset apply to the band.
The pixel selected is requested by x/y coordinate on the commandline, or read from stdin. More than one coordinate pair can be supplied when reading coordinatesis from stdin. By default pixel/line coordinates are expected. However with use of the -geoloc, -wgs84, or -l_srs switches it is possible to specify the location in other coordinate systems.
The default report is in a human readable text format. It is possible to instead request xml output with the -xml switch.
For scripting purposes, the -valonly and -lifonly switches are provided to restrict output to the actual pixel values, or the LocationInfo files identified for the pixel.
Simple example reporting on pixel (256,256) on the file utm.tif.
$ gdallocationinfo utm.tif 256 256 Report: Location: (256P,256L) Band 1: Value: 115
Query a VRT file providing the location in WGS84, and getting the result in xml.
$ gdallocationinfo -xml -wgs84 utm.vrt -117.5 33.75 <Report pixel="217" line="282"> <BandReport band="1"> <LocationInfo> <File>utm.tif</File> </LocationInfo> <Value>16</Value> </BandReport> </Report>
Frank Warmerdam warmerdam [at] pobox.com