= [wiki:FAQ] - Coordinate Systems and Projections =

== What are ''Well Known Text'' projections, and how do I use them? ==

''OpenGIS Well Known Text'' is a textual format for defining coordinate systems. It is loosely based on the [http://www.epsg.org/ EPSG] coordinate systems model. While GDAL itself just passes these definitions around as text strings, there is also an [http://www.gdal.org/ogr/classOGRSpatialReference.html OGRSpatialReference] class in ''gdal/ogr'' for manipulating them and a linkage to [http://proj.maptools.org/ PROJ.4] for transforming between coordinate systems. The OGRSpatialReference, and PROJ.4 linkaged (but not PROJ.4 itself) is linked into the GDAL shared library by default. More documentation on WKT and OGRSpatialReference can be found in the [http://www.gdal.org/ogr/osr_tutorial.html OGR Projections Tutorial].

== Can I reproject rasters with GDAL? ==

Yes, you can use the gdalwarp utility program or programmatically use the [http://www.gdal.org/classGDALWarpOperation.html GDALWarpOperation] class described in the [http://www.gdal.org/warptut.html GDAL Warp API Tutorial].