[GRASS-user] How to interpolate a gps trackpoint-"cloud" into a raster DTM

GRASS GRASS user
1

Hi List,
I have two ascii files with points:

way points:
#N|E|Height|name
4416857|5359613|411|040
4416926|5359382|419|041
4416572|5358196|431|042

and track points:
#N|E|Height
4416930|5360187|407
4416921|5360166|408
4416914|5360153|409
4416900|5360127|409

I imported them with v.in.ascii to vector layers

cat tp.csv | v.in.ascii -z z=3 cat=0 out=tp_point01 columns=‘x double, y double, z double’

cat wp.csv | v.in.ascii -z z=3 cat=0 out=wp_point01 columns=‘x double, y double, z double,label_name varchar(20)’

Now first I want to interpolate them to raster files
I used
v.to.rast *p_point01 o=*p_p01_ras u=z
I couldn’t keep the label ‘name’ in way points but I don’t care.

So how to hull the outer points in one area/mask to interpolate only the inner area
( I want to integrate this area in another DTM with r.mapcalc afterwards)
I read about a command named s.hull but there are no site - ‘s.’ - commands in my version (6.2.2 cvs on Ubuntu)

And which command may the best to interpolate the model?
r.surf.???

Thx a lot for hints

Om shantih
Philipp

2

On Friday 02 November 2007, opopanax wrote:

Hi List,
I have two ascii files with points:

way points:
#N|E|Height|name
4416857|5359613|411|040
4416926|5359382|419|041
4416572|5358196|431|042

and track points:
#N|E|Height
4416930|5360187|407
4416921|5360166|408
4416914|5360153|409
4416900|5360127|409

I imported them with v.in.ascii to vector layers

cat tp.csv | v.in.ascii -z z=3 cat=0 out=tp_point01 columns='x double, y
double, z double'

cat wp.csv | v.in.ascii -z z=3 cat=0 out=wp_point01 columns='x double, y
double, z double,label_name varchar(20)'

Now first I want to interpolate them to raster files
I used
v.to.rast *p_point01 o=*p_p01_ras u=z
I couldn't keep the label 'name' in way points but I don't care.

So how to hull the outer points in one area/mask to interpolate only the
inner area
( I want to integrate this area in another DTM with r.mapcalc afterwards)
I read about a command named s.hull but there are no site - 's.' -
commands in my version (6.2.2 cvs on Ubuntu)

And which command may the best to interpolate the model?
r.surf.???

Thx a lot for hints

Om shantih
Philipp

1. import files : v.in.ascii
2. optionally merge together: v.patch
3. compute convex hull(s): v.hull
4. interpolate:
4a. set region extent and res: g.region
4b. interpolate with RST: v.surf.rst
5. patch into existing DTM: r.patch ?

Cheers,

Dylan

--
Dylan Beaudette
Soil Resource Laboratory
http://casoilresource.lawr.ucdavis.edu/
University of California at Davis
530.754.7341