GDAL: the definitive FREE GIS software

This field is growing and there are a lot of GIS software applications out there to choose from but I am learning that many of you really don’t understand how powerful GDAL/OGR and the FWTools suite really is. When duty calls and I need to do some heavy reprojecting, import/export, compression, etc…I usually always go to GDAL and FWTools to get the job done.

The following utility programs are distributed with GDAL and are among the most powerful command line GIS applications available today. I for one have beaten gdalwarp to death! I will include all that it can do in later posts. Until then, here is the list of what is included in the FWTools installer for Windows and Linux.

• gdalinfo – report information about a file.
• gdal_translate – Copy a raster file, with control of output format.
• gdaladdo – Add overviews to a file.
• gdalwarp – Warp an image into a new coordinate system.
• gdaltindex – Build a MapServer raster tileindex.
• gdalbuildvrt – Build a VRT from a list of datasets.
• gdal_contour – Contours from DEM.
• gdaldem – Tools to analyze and visualize DEMs.
• rgb2pct.py – Convert a 24bit RGB image to 8bit paletted.
• pct2rgb.py – Convert an 8bit paletted image to 24bit RGB.
• gdal_merge.py – Build a quick mosaic from a set of images.
• gdal2tiles.py – Create a TMS tile structure, KML and simple web viewer.
• gdal_rasterize – Rasterize vectors into raster file.
• gdaltransform – Transform coordinates.
• nearblack – Convert nearly black/white borders to exact value.
• gdal_retile.py – Retiles a set of tiles and/or build tiled pyramid levels.
• gdal_grid – Create raster from the scattered data.
• gdal_proximity.py – Compute a raster proximity map.
• gdal_polygonize.py – Generate polygons from raster.
• gdal_sieve.py – Raster Sieve filter.
• gdal_fillnodata.py – Interpolate in nodata regions.
• gdal-config – Get options required to build software using GDAL.

Note that a lot of these apps are python scripts than can be run just about anywhere. I have done quite a bit of processing with FWTools apps, especially gdalwarp, gdal_translate and then gdal_contour. If you have a project that requires some serious processing power, check some of these out. You won’t be disappointed…Note: Most FOSS GIS applications available today use GDAL and OGR on the back end in some way, shape or form. See the list here!

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