# Free surface output¶

## Introduction¶

Velocities and ground deformations can be imaged as a surface representation, in a file that can be opened in ParaView. Threads or nodes can be dedicated to write this output (see Asynchronous Output), but it is usually not necessary. The output to enabled in the Output namelist:

&Output
SurfaceOutput = 1
SurfaceOutputRefinement = 1
SurfaceOutputInterval = 0.5
/


If SurfaceOutputRefinement = 0, one triangle is outputted for each mesh cell. The unknowns are evaluated at the center of each cell. SurfaceOutputRefinement = 1 subdivides each triangle, into 4 subtriangles. Higher SurfaceOutputRefinement would further subdivide each subtriangle.

## variables¶

u, v, w: ground velocities, x y and z components
U, V, W: ground displacements, x y and z components