[GIS] How to create Raster statistics with GDAL externally

gdalgdalinfopythonstatistics

If I want to create a GDAL PAM statistics file with the command gdalinfo -stats from a GRIB file, e.g. needed for DynamicColorMapping, GDAL only creates the statistics internally inside the sourcefile. Is it possible to force gdalinfo -stats to create the additional file (.aux.xml)?

A way to do this is programmatically with Python and to tinker with the XML, but that doesn't fit my needs.

Best Answer

As a workaround you can use command

gdalinfo -stats -hist input.tif

Selecting the histogram option triggers the creation of input.tif.aux.xml file.

EDIT

I have learned that actually there is no need to use the -hist workaround. There is a GDAL configuration option GDAL_PAM_ENABLED that forces the creation of the .aux.xml file. Usage example:

gdalinfo test.tif -stats --config GDAL_PAM_ENABLED TRUE

Related Solutions

Python GDAL – How to Generate Statistics for GTiff Files

You can use GetStatistics Method to get the stats.

eg.

stats =   ds.GetRasterBand(1).GetStatistics(0,1)

it will return (Min, Max, Mean, StdDev)

so the xml can be read:

<PAMDataset>
  <PAMRasterBand band="1">
    <Metadata>
      <MDI key="STATISTICS_MINIMUM">stats[0]</MDI>
      <MDI key="STATISTICS_MAXIMUM">stats[1]</MDI>
      <MDI key="STATISTICS_MEAN">stats[2]</MDI>
      <MDI key="STATISTICS_STDDEV">stats[3]</MDI>
    </Metadata>
  </PAMRasterBand>
</PAMDataset>

I dont know any pythonic way to create/manipulate xml file.But given the simplistic nature of the accompanying xml it should pretty trival to create one it with file I/O operations

[GIS] How to save json returned by gdalinfo in python variable

I've done this with calls to curl, here's a snippet. The trick is to use subprocess.check_output instead of os.system:

import subprocess
layer_name = subprocess.check_output("curl -s {0}/{1}?f=pjson | json -a name".format(service_url, layer_number), shell=True)

So in your case, perhaps something like (untested):

import subprocess
ret = subprocess.check_output("gdalinfo -json C:\Users\Gurminder\Documents\Git\Dump\s1a-ew-grd-hh-20160725t043517-20160725t043617-012300-01322b-001.tiff", shell=True)

Since you are getting json back, you might be able to do the following, otherwise you might just get a string back instead of json (untested):

import json
import subprocess
actual_json = json.loads(subprocess.check_output("gdalinfo -json C:\Users\Gurminder\Documents\Git\Dump\s1a-ew-grd-hh-20160725t043517-20160725t043617-012300-01322b-001.tiff", shell=True))

Best Answer

Related Solutions

Python GDAL – How to Generate Statistics for GTiff Files

[GIS] How to save json returned by gdalinfo in python variable

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