[GRASS-user] LIDAR tools and topology (unable to open ... on level 2)

GRASS GRASS user
1

I find that after running each of the v.lidar.* the resulting vector lacks topology, so I can't view the categories:

i.e. (after v.lidar.correct):

GRASS 6.4.2RC1 (ITM):~/GIS/DEM/LIDAR_EinYahav > v.category south_correct opt=report
ERROR: Unable to open vector map <south_correct@EinYahav_LIDAR> on level 2.
        Try to rebuild vector topology by v.build.

So I run v.build, and then I get the vector with 4 different layers, each with a different number of cat values (different max category).

Is this what is supposed to happen? Should I add a v.build step between each of the v.lidar.* stages?

Thanks,

Micha

2

On Fri, Dec 16, 2011 at 7:03 AM, Micha Silver <micha@arava.co.il> wrote:

I find that after running each of the v.lidar.* the resulting vector lacks
topology, so I can't view the categories:

i.e. (after v.lidar.correct):

GRASS 6.4.2RC1 (ITM):~/GIS/DEM/LIDAR_EinYahav > v.category south_correct
opt=report
ERROR: Unable to open vector map <south_correct@EinYahav_LIDAR> on level 2.
Try to rebuild vector topology by v.build.

Oops. v.category should not really need topology.

So I run v.build, and then I get the vector with 4 different layers, each
with a different number of cat values (different max category).

Is this what is supposed to happen? Should I add a v.build step between each
of the v.lidar.* stages?

The v.lidar.* tools (as well as the v.surf.* tools) are supposed to
work with massive point data for which topology is not needed. Most
vector modules do require topology, however, so if you want to use
those, you need to build topology, but I would not do that by default
for point data.

Markus M

Thanks,

Micha

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3

On Sun, Dec 18, 2011 at 12:12 PM, Markus Metz
<markus.metz.giswork@googlemail.com> wrote:

On Fri, Dec 16, 2011 at 7:03 AM, Micha Silver <micha@arava.co.il> wrote:

I find that after running each of the v.lidar.* the resulting vector lacks
topology, so I can't view the categories:

i.e. (after v.lidar.correct):

GRASS 6.4.2RC1 (ITM):~/GIS/DEM/LIDAR_EinYahav > v.category south_correct
opt=report
ERROR: Unable to open vector map <south_correct@EinYahav_LIDAR> on level 2.
Try to rebuild vector topology by v.build.

Oops. v.category should not really need topology.

For the record: MarkusM has fixed this in trunk in
http://trac.osgeo.org/grass/changeset/49959

Markus