Rasters

The input and outputfiles of WaTEM/SEDEM are based on geospatial rasters. Every raster is defined with a cell size (e.g. 20x20m or 20x50m) and a number of rows and columns. Geospatial rasters are placed within a reference system (e.g. WGS84 or EPSG:31370) to situate these rasters in the right location.

Format

All input and output rasters are Idrisi-rasters or Saga-rasters and should have the same amount of columns, rows and cell size. If one of the input rasters has a different spatial extent, the model will raise an exception and will stop the execution.

Idrisi- and Saga-rasters are the native file format of respectivily Idrisi GIS and SAGA GIS, but can be opened, edited and saved with almost every GIS-package like QGIS or SAGA-GIS, with the aid of the GDAL library.

Both file formats contain a binary dump of the rasterdata (.rst and .sdat) and an ascii metadata file (.rdc and .sgrid). Saga-rasters can also have a .prj-file containing information on the projection of the raster.

To switch between these two raster formats, use the Saga grids-option.

Raster Coordinates

The origin of the raster coordinatesytem in WaTEM/SEDEM lies in the upper left rastercell. This cell has the raster coordinates (1,1).