GDAL

Installation

Best install using standard system package manager, such as apt-get (Ubuntu), yum (Fedora), or macports (OSX).

Download

The current download page is http://download.osgeo.org/gdal/. However, web searches for the code or documentation lead to many dead links to defuncts sites. In particular, almost all links leading inside https://gdal.org/ from internet search engines are dead.

Documentation

• Web searches for "gdal documentation" are futile, but there is index to just that at https://gdal.org and wiki https://trac.osgeo.org/gdal/wiki, which also links to alternative download pages. But that wiki seems old, there is a new wiki at https://wiki.osgeo.org/wiki/Main_Page.
• The software installs without man pages and typing gdal utilities from the command line with -help gives only a brief list of options. But the following works:
  • Download the appropriate version of sources as tar.gz file and expand the file
  • install doxygen if needed, and type doxygen in the top directory of the source
  • Open html/index.html in a web browser
• Documentation was installed as described above for version 2.4.0 and version 3.0.0
• There is https://live.osgeo.org/en/quickstart/gdal_quickstart.html

How to

Subset a dataset

gdal_translate -projwin_srs '+proj=longlat +datum=WGS84 +no_defs' -projwin -120 39 -119 38 file.tif subset.tif
gdal_translate -projwin_srs '+proj=stere +lat_0=38.5 +lon_0=-119.5 +datum=WGS84 +units=km +no_defs' -projwin -50 50 50 -50 file.tif subset.tif

External links

• https://gis.stackexchange.com/questions/164853/reading-modifying-and-writing-a-geotiff-with-gdal-in-python
• https://spatialreference.org/ translation of EPSG codes and proj4 etc.
• https://medium.com/planet-stories/a-gentle-introduction-to-gdal-part-1-a3253eb96082
• https://gis.stackexchange.com/questions/33330/how-do-i-extract-a-rasters-extent-in-python
• Datum and ellipsoid are not the same thing
• How to call gdal translate from python code
• Reading raster files with GDAL
• GDAL and OGR utilities as library
• Obtain latitude and longitude from a GeoTIFF file
• Python GDAL/OGR Cookbook
• https://stackoverflow.com/questions/50191648/gis-geotiff-gdal-python-how-to-get-coordinates-from-pixel
• OSGeo Python Library
• GDAL/OGR in Python (old wiki)
• https://stackoverflow.com/questions/52777153/convert-longitude-latitude-to-pixel-values-using-gdal
• https://www.geos.ed.ac.uk/~smudd/TopoTutorials/html/tutorial_raster_conversion.html
• https://pypi.org/project/geoio/
• https://gisgeography.com/free-gis-software/
• https://qgis.org
• https://www.qgistutorials.com
• The pitfalls of Lambert conformal projection in WRF and MM5
• Map projections in WRF: it's easy to get it wrong includes also examples of maps from WRF using salem
• WGS84 NAD83 simple explanations, not technical
• https://www.codeguru.com/cpp/g-m/bitmap/viewers/article.php/c9187/2D--3D-Visualization-Techniques-for-GeoReferenced-Images.htm
• http://pyproj4.github.io/pyproj/html/api/geod.html
• https://janakiev.com/blog/gps-points-distance-python/
• https://trac.osgeo.org/gdal/ticket/4267 on stereo projection

Glossary

• WKT: Well-known text representation of coordinate reference systems or Well-known text representation of geometry, a text markup language for representing vector geometry objects
• SRS: Spatial reference system: a complete set of parameters that determine how to associate a point on a map with a point on the Earth surface (system of coordinates, map projection, and datum).
• Latitude - there is more than one because the Earth is not a sphere

See also

• How to run WRF-Fire with real data
• WPS with GeoTIFF support