[GRASS-user] Having problems with v.in.ogr

GRASS GRASS user
1

Hi

I am having issues importing a shapefile using v.in.ogr

Using basic command v.in.ogr dsn=shapefile layer=shapefile name output=elev

getting the following areas for every entry

GRASS_INFO_WARNING(29…,50…): Area size 6.5e-11, area not imported.
…
[warning sign] area size 6.5e-11, area not imported
…

THe shapefile was generated by a Greenstar 2 GPS receiver (John Deere).

There are many columns in the shapefile (30).

How can i limit the number of columns i read in, and how to set which column is the elevation column (or is ELEVATION okay)?

I am assuming it has something to do with the way the shapefile was genereated and the precision/length of the numeric fields in the database???

Please can ayone help with this?

Also what is a good .dbf viewer for KDE?

Thanks,
Ed

2

Edward Tomlinson wrote:

I am having issues importing a shapefile using v.in.ogr

Using basic command v.in.ogr dsn=shapefile layer=shapefile name
output=elev

getting the following areas for every entry

GRASS_INFO_WARNING(29..,50..): Area size 6.5e-11, area not imported.
...
[warning sign] area size 6.5e-11, area not imported
...

Reduce v.in.ogr's min_area option.

  min_area Minimum size of area to be imported (square units).
             Smaller areas and islands are ignored. Should be
             greater than snap^2
             default: 0.0001

THe shapefile was generated by a Greenstar 2 GPS receiver (John
Deere).

could you make a small sample available somewhere?

There are many columns in the shapefile (30).

How can i limit the number of columns i read in,

you can't during import, but you can later with v.db.dropcol

and how to set which column is the elevation column (or is ELEVATION
okay)?

I am not sure if there is a vector tool to change a 2D vector + numeric
column into a 3D vector directly.
v.out.ascii + "v.in.ascii z=" would probably do it.

but most GRASS DEM creation tools will let you specify a 2D vector + elev
column name instead of needing a 3D vector as the input.

I am assuming it has something to do with the way the shapefile was
genereated and the precision/length of the numeric fields in the
database???

As long as the datafile is not corrupt you /should/ be able to work with
whatever is in it.

Also what is a good .dbf viewer for KDE?

Don't know about KDE, but "dbview -bt" is nice from the command line, and
OpenOffice is probably ok if there are less than a few tens of thousands of
entries.

Hamish

3

Hi Hamish,

Yes, changing the default grid size fixed my problem. I initially read it as square meters (or assumed), however when i looked at it again i realised my mistake. I have been away most of last week so have not had a chance to progress any further with DEM creation.

As far as making the shapefile available it is around 5mb in size. Also i dont really have any where to put it except one of the commercial sites. However i can still make a copy available if you like.

Thanks,
Ed

On 04/07/07, Hamish <hamish_nospam@yahoo.com> wrote:

Edward Tomlinson wrote:

I am having issues importing a shapefile using v.in.ogr

Using basic command v.in.ogr dsn=shapefile layer=shapefile name
output=elev

getting the following areas for every entry

GRASS_INFO_WARNING(29…,50…): Area size 6.5e-11, area not imported.
…
[warning sign] area size 6.5e-11, area not imported
…

Reduce v.in.ogr’s min_area option.

min_area Minimum size of area to be imported (square units).
Smaller areas and islands are ignored. Should be
greater than snap^2
default: 0.0001

THe shapefile was generated by a Greenstar 2 GPS receiver (John
Deere).

could you make a small sample available somewhere?

There are many columns in the shapefile (30).

How can i limit the number of columns i read in,

you can’t during import, but you can later with v.db.dropcol

and how to set which column is the elevation column (or is ELEVATION
okay)?

I am not sure if there is a vector tool to change a 2D vector + numeric
column into a 3D vector directly.
v.out.ascii + “v.in.ascii z=” would probably do it.

but most GRASS DEM creation tools will let you specify a 2D vector + elev
column name instead of needing a 3D vector as the input.

I am assuming it has something to do with the way the shapefile was
genereated and the precision/length of the numeric fields in the
database???

As long as the datafile is not corrupt you /should/ be able to work with
whatever is in it.

Also what is a good .dbf viewer for KDE?

Don’t know about KDE, but “dbview -bt” is nice from the command line, and
OpenOffice is probably ok if there are less than a few tens of thousands of
entries.

Hamish