[GRASS-user] v.in.ascii error: G_realloc

GRASS GRASS user
1

>> Hi,
>> thanks Markus for your help. v.in.ascii is working fine now.
>> But now I have problems with the created vector file. I think because

of

the
>> missing topology.
>>
>> If I want to use the created vector file for example with v.patch I

get

the
>> error:
>>
>> Cannot open old vector dtm1107_32@Solothurn on level 2
>>
>> The same error if I use g.region vect=dtm1107_32
>
>Only a couple of commands work without topology (to allow
>working with large number of points). Would be good if
>someone documents that in the Wiki.
>
>> Another example: If I use v.surf.rst I get the error:
>>
>> Vector is not 3D
Ok I regarded too much on the -b Flag and forgot furthermore the -z flag
>
>Maybe you forgot the -z setting in v.in.ascii to import as 3D?
>
>Markus

But what can I do with g.region and v.patch?

Looks like programming...

I do need these functions!

What do you exactly want to do with 11 Mpoints? Lidar?

I have about 50 tiles with geodetic points. These geodetic points should be
transformed into a Digital terrain model (DTM) by v.surf.rst. If somebody
wants a DTM for a defined extract of the area the DTM should be calculated
exactly for this area. Everything should be automated by a PHP-Script. I
thought about first identifing the needed tiles then patch these tiles with
v.patch, setting the region to the defined extract (g.region) and as last
point transform the points by v.surf.rst into a DTM.
Hope I could make clear what I want to do?!.It's not that easy for me in
English.

greets

Michael

ciao
Markus

Any suggestions?

Greets

Michael

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--
Markus Neteler <neteler itc it> http://mpa.itc.it/markus/
ITC-irst - Centro per la Ricerca Scientifica e Tecnologica
MPBA - Predictive Models for Biol. & Environ. Data Analysis
Via Sommarive, 18 - 38050 Povo (Trento), Italy

2

Praktikant/in2 ARP napisa?(a):

I have about 50 tiles with geodetic points. These geodetic points should be
transformed into a Digital terrain model (DTM) by v.surf.rst.

Can you patch those 50 tiles points outside Grass?

If they are only plain text files, formatted like

x1 y1 z1
x2 y2 z2
x3 y3 z3
...

it will be very easy on Unix:

cat patch49 >> patch50
cat patch48 >> patch50
cat patch47 >> patch50
...

and so forth till they all are in a one file, the "patch50".

Now import that huge patch50 as 3D, not building topology (v.in.ascii -zb).

Set the region *manually* to cover the whole vector patch50 ('g.region
vect=' will not work with topologyless vector as you know, so you must
use 'g.region n= s= e= w= res=' explicitely).

Interpoloate dem out of your 3D points (v.surf.rst layer=0).

If somebody wants a DTM for a defined extract of the area the DTM should be calculated
exactly for this area. Everything should be automated by a PHP-Script. I
thought about first identifing the needed tiles then patch these tiles with
v.patch, setting the region to the defined extract (g.region) and as last
point transform the points by v.surf.rst into a DTM.

It will be not optimal at all to interpolate new dem each time a subset
is required. Better interploate full dem only once (as I described
above) and only adjust region settings as needed, for each query your
PHP script gets, with g.region, then use 'r.mapcalc current_subset=dem'
to extract that particular subset from the whole dem. Easier and much
faster.

Best,
Maciek