[GRASS-user] LiDAR interpolation (v.surf.bspline)

Hamish hamish_b at yahoo.com
Sun Jan 30 17:08:00 EST 2011

Carlos Grohmann wrote:
> > Also, the wiki page and man pages for v.lidar.* cite
> > examples of lidar data with two returns. How well should
> > the commands run with 4 returns? Any big changes in th
> > procedure explained in the wiki?
Markus M:
> It is possible that the lidar toolchain does not work with
> 4 return because it classifies points into first or last
> return, nothing in between. In theory, it would suffice to
> identify the first and the last return, independent of the
> number of returns, in order to get a DSM and a DTM. The lidar
> filtering toolchain should work if you could remove 2. and 3.
> returns first.

set the resolution fine enough and r.in.xyz will allow you to
deal with the 4 returns any way you like.

if you don't like the gridding aspect of it, and the lat/lon for
all 4 retuns is identical, a small python or awk script could do
the pre-processing for you in a simple and clear way. maybe you
have to pipe it through `sort -n` first (but hopefully not).



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