[GRASS-user] Using v.surf.rst

GRASS GRASS user
1

I’m very new to GRASS and an experienced programmer.

My goal is to import isolines (elevation lines) as well as elevation points from another mapping program into GRASS and then interpolate a raster based on the vector data and then export as a DEM file.

To that end I have reviewed

http://grass.osgeo.org/grass64/manuals/html64_user/v.in.ascii.html

http://grass.osgeo.org/grass64/manuals/html64_user/v.surf.rst.html

I think I understand the principals but am getting stuck on several details.

As a simple test I attempted to create an ASCII file with X Y Z coordinates:

myFile.txt

593493|4914730|123

591950|4923000|222

589860|4922000|232

590400|4922820|143

593549|4925500|442

600375|4925235|342

import with

v.in.ascii –z input=myFile.txt output=secondTry z=3

I get v.in.ascii complete (no error messages)

and then

run v.surf.rst input=secondTry@PERMANENT elev=secondTryRaster

This yields the error

some points outside of region – will ignore…

there are points outside specified 2D/3D region–ignored 6 points

ERROR2: zero points in the given region!

ERROR: Input failed

Keeping in mind I’m completely new to GRASS (and don’t understand a lot of the jargon), can you explain what I’m doing wrong?

Also, can you recommend a tutorial that covers this type of conversion oriented toward beginners?

Thanks!

Eric

After importing the data points, I do not see anything at all visually in GRASS GIS Map Display.

2

Hello Eric

there are points outside specified 2D/3D region--ignored 6 points

ERROR2: zero points in the given region!

ERROR: Input failed

Keeping in mind I’m completely new to GRASS (and don’t understand a
lot of the jargon), can you explain what I’m doing wrong?

Probably, you aren't defining the working "region". See command
g.region.

Example: g.region -a vect=secondTry@PERMANENT res=10 -p

This command will define the working region by the spatial extent of
"secondTry", defining and aligning a 10 meters resolution with the
region extent and printing the result.

Also, can you recommend a tutorial that covers this type of conversion
oriented toward beginners?

I strongly suggest the book OPEN SOURCE GIS - A GRASS GIS Approach, 3rd
edition.

Luís Ferreira

3

Eric pisze:

I’m very new to GRASS and an experienced programmer.

My goal is to import isolines (elevation lines) as well as elevation points from another mapping program into GRASS and then interpolate a raster based on the vector data and then export as a DEM file.

To that end I have reviewed

http://grass.osgeo.org/grass64/manuals/html64_user/v.in.ascii.html

http://grass.osgeo.org/grass64/manuals/html64_user/v.surf.rst.html

I think I understand the principals but am getting stuck on several details.

As a simple test I attempted to create an ASCII file with X Y Z coordinates:

myFile.txt

593493|4914730|123

591950|4923000|222

589860|4922000|232

590400|4922820|143

593549|4925500|442

600375|4925235|342

import with

v.in.ascii –z input=myFile.txt output=secondTry z=3

I get v.in.ascii complete (no error messages)

and then

run v.surf.rst input=secondTry@PERMANENT elev=secondTryRaster

This yields the error

some points outside of region -- will ignore...

there are points outside specified 2D/3D region--ignored 6 points

ERROR2: zero points in the given region!

ERROR: Input failed

Keeping in mind I’m completely new to GRASS (and don’t understand a lot of the jargon), can you explain what I’m doing wrong?

Also, can you recommend a tutorial that covers this type of conversion oriented toward beginners?

Thanks!

Eric

After importing the data points, I do not see anything at all visually in GRASS GIS Map Display.

------------------------------------------------------------------------

_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
  

It simply menas that data are outside your region

try:

g.region vect=secondTry

HTH
J.

4

Awesome! Importing the points worked.

My real source data is defined as a combination of points (which I can now import) and 2D splines (representing the isolines) that may or may not form a closed shape, like this:

|2D Smooth Polygon:
| Height 2885
| smoothing method: Cubic B-Spline
| node 1 at 564.51807,742.19873
| node 2 at 249.51805,570.15057
| node 3 at 578.43365,137.50000
| node 4 at 919.99994,451.23495
| node 5 at 708.73486,742.19879
| node 6 at 541.74695,727.01807

I can easily reformat the data.

How do I import a spline like this into GRASS in preparation for v.surf.rst (or other vector to raster methods)?

Thanks!

Eric