## DESCRIPTION

Converts one 3D raster map into several 2D raster maps (depends on depths). If the 2D and 3D region settings are different, the 3D resolution will be adjusted to the 2D resolution (the depths are not touched). The user can force r3.to.rast to use the 2D resolution of the input 3D raster map for the output maps, independently from the current region settings.

How r3.to.rast works

### Map type conversions

Type of resulting 2D raster maps is determined by the type of the input 3D raster, i.e. 3D raster of type DCELL (double) will result in DCELL 2D rasters. A specific type for 2D rasters can be requested using the type option.

The type option is especially advantageous when the 3D raster map stores categories (which need to be stored as floating point numbers) and the 2D raster map should be also categorical, i.e. use integers. The type is set to `CELL` in this case.

### Modifying the values

The values in the 3D raster map can be modified prior to storing in the 2D raster map. The values can be scaled using the option multiply and a constant value can be added using the option add. The new value is computed using the following equation:

    y = ax + b

where x is the original value, a is the value of multiply option, b is the value of add option, and y is the new value. When multiply is not provided, the value of a is 1. When add is not provided, the value of b is 0.

## NOTES

Every slice of the 3D raster map is copied to one 2D raster map. The maps are named like output_slicenumber. Slices are counted from bottom to the top, so the bottom slice has number 1.

The number of slices is equal to the number of depths.

To round floating point values to integers when using `type=CELL`, the add option should be set to 0.5.

## SEE ALSO

r3.cross.rast, r3.out.vtk, r3.out.ascii, g.region

## AUTHOR

Sören Gebbert Vaclav Petras, NCSU GeoForAll Lab

Last changed: $Date$