Tutorial: Introduction to GDAL

4.1. Convert raster formats

gdal_translate's primary function is to change between image formats. The basic syntax is:

gdal_translate -of FORMAT inputFile outputFile

All supported formats can be found here.

Now we are going to convert the DEM from geoTiff to SAGA format. SAGA is a GIS which has its own -gdal-supported- binary format with the .sdat extension.

1. Execute the following command:
gdal_translate -of SAGA dem_rd.tif dem_rd.sdat

Some formats need more arguments. PCRaster for examples needs a specification of the data type (boolean, nominal, scalar, etc.). Let's convert the same data to PCRaster format.

2. Execute the following command:
gdal_translate -of PCRaster -ot Float32 -mo "VS_SCALAR" dem_rd.tif dem_rd.map

To convert to PCRaster format you need to know the data type of the raster. In the example above the DEM is continuous data, so the data type is scalar. If the layer was discrete (classes) then the data type was nominal.

Data Type	-of	-mo
Boolean	Byte	"VS_BOOLEAN"
Nominal	Int32	"VS_NOMINAL"
Ordinal	Int32	"VS_ORDINAL"
Scalar	Float32 or Float64	"VS_SCALAR"
Direction	Float32 or Float64	"VS_DIRECTION"
LDD	Int32	"VS_LDD"