gdallocationinfo

Raster query tool

Synopsis

Usage: gdallocationinfo [--help] [--help-general]
                        [-xml] [-lifonly] [-valonly]
                        [-E] [-field_sep <sep>] [-ignore_extra_input]
                        [-b <band>]... [-overview <overview_level>]
                        [-l_srs <srs_def>] [-geoloc] [-wgs84]
                        [-oo <NAME>=<VALUE>]... <srcfile> [<x> <y>]

Description

The gdallocationinfo utility provide a mechanism to query information about a pixel given its location in one of a variety of coordinate systems. Several reporting options are provided.

--help: Show this help message and exit

--help-general: Gives a brief usage message for the generic GDAL commandline options and exit.

-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 (i.e. for identifying impacted file from VRT).

-valonly: The only output is the pixel values of the selected pixel on each of the selected bands. By default, the value of each band is output on a separate line, unless -field_sep is specified.

-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.

-oo <NAME>=<VALUE>: Dataset open option (format specific)

-ignore_extra_input: New in version 3.9.

Set this flag to avoid extra non-numeric content at end of input lines to be appended to the output lines in -valonly mode (requires -field_sep to be also defined), or as a dedicated field in default or -xml modes.

-E: New in version 3.9.

Enable Echo mode, where input coordinates are prepended to the output lines in -valonly mode.

-field_sep <sep>: New in version 3.9.

Defines the field separator, used in -valonly mode, to separate different values. It defaults to the new-line character, which means that when querying a raster with several bands, the output will contain one value per line, which may make it hard to recognize which value belongs to which set of input x,y points when several ones are provided. Defining the field separator is also needed

<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:

The location of the pixel in pixel/line space.
The result of a LocationInfo metadata query against the datasource. This is implemented for VRT files which will report the file(s) used to satisfy requests for that pixel, and by the MBTiles driver.
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 command line, or read from stdin. More than one coordinate pair can be supplied when reading coordinates from stdin. By default integer 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.

Examples

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>

Reading location from stdin.

$ cat coordinates.txt
443020 3748359
441197 3749005
443852 3747743

$ cat coordinates.txt | gdallocationinfo -geoloc utmsmall.tif
Report:
  Location: (38P,49L)
  Band 1:
    Value: 214
Report:
  Location: (7P,38L)
  Band 1:
    Value: 107
Report:
  Location: (52P,59L)
  Band 1:
    Value: 148

$ cat coordinates.txt | gdallocationinfo -geoloc -valonly -E -field_sep , utmsmall.tif
443020,3748359,214
441197,3749005,107
443852,3747743,148