NAME¶
gdallocationinfo - gdallocationinfo raster query tool
SYNOPSIS¶
Usage: gdallocationinfo [--help-general] [-xml] [-lifonly] [-valonly]
[-b band]* [-overview overview_level]
[-l_srs srs_def] [-geoloc] [-wgs84]
srcfile [x y]
DESCRIPTION¶
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.
- -xml:
- The output report will be XML formatted for convenient post
processing.
- -lifonly:
- The only output is filenames production from the LocationInfo request
against the database (ie. for identifying impacted file from VRT).
- -valonly:
- 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.
- -geoloc:
- Indicates input x,y points are in the georeferencing system of the
image.
- -wgs84:
- Indicates input x,y points are WGS84 long, lat.
- srcfile:
- The source GDAL raster datasource name.
- x:
- X location of target pixel. By default the coordinate system is pixel/line
unless -l_srs, -wgs84 or -geoloc supplied.
- y:
- 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.
It is anticipated that additional reporting capabilities will be added to
gdallocationinfo in the future.
EXAMPLE¶
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>
AUTHORS¶
Frank Warmerdam warmerdam@pobox.com