[GRASS-user] r.los

[Maciej Sieczka]

Michael Barton wrote:
> GRASS has 2 routines specially designed to interpolate raster maps from
> contours.

...

> 2. Use v.surf.rst: More sophisticated and complicated module, but will read
> your vector contours directly. Check the manual for details.

v.surf.rst is not designed for elevation contours lines input. It
*might* work well with contours, but in general it prefers homogenous
points input, like LIDAR or SRTM. In case of elavation contour lines,
which have irregular distribution by nature, RST produces curvature
artifacts. Also, as v.surf.rst uses segmentation to preserve memory,
any clustered input tends to lead to "stairy" artifacts at segments'
joins. Both side effects are possible to minimise bu adjusting tension,
smoothing and other parameters, but success is not guaranteed.

Maciek