GDAL
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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