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

Markus Metz markus.metz.giswork at googlemail.com
Sun Dec 18 06:12:07 EST 2011

On Fri, Dec 16, 2011 at 7:03 AM, Micha Silver <micha at 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 at 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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