[GRASS-user] v.in.lidar finds 0 points in GRASS 7

Michael_Moore2 · February 20, 2014, 1:24am

Hello,

I think I’m doing something wrong with importing lidar data in GRASS 7.

My data is a laz file from the state of Minnesota.

The complicating factor is that the EPSG code is set incorrectly – EPSG:32715 / UTM 15 S instead of EPSG:26715/UTM 15 N. My region is set to the correct 26715.

I am using the GUI, but the command that it generates is

v.in.lidar -p -o --overwrite input=/data/3542-27-22.laz output=test

The output is:

Over-riding projection check
Importing 0 points…
Building topology for vector map test@stuporglue…
Registering primitives…
0 primitives registered
0 vertices registered
Building areas…
0 areas built
0 isles built
Attaching islands…
Attaching centroids…
Number of nodes: 0
Number of primitives: 0
Number of points: 0
Number of lines: 0
Number of boundaries: 0
Number of centroids: 0
Number of areas: 0
Number of isles: 0
0 points imported

lasinfo reports 12588100 points.

I’d be happy to get this imported either through the command line or the GUI, but my goal is to understand enough about GRASS to script the creation of a state-wide DSM from LiDAR data.

Thanks,
Michael Moore

Markus_Metz · February 20, 2014, 7:38am

On Thu, Feb 20, 2014 at 2:24 AM, Michael Moore <stuporglue@gmail.com> wrote:

Hello,

I think I'm doing something wrong with importing lidar data in GRASS 7.

My data is a laz file from the state of Minnesota.

The complicating factor is that the EPSG code is set incorrectly --
EPSG:32715 / UTM 15 S instead of EPSG:26715/UTM 15 N. My region is set to
the correct 26715.

I am using the GUI, but the command that it generates is

v.in.lidar -p -o --overwrite input=/data/3542-27-22.laz output=test

The output is:

Over-riding projection check
Importing 0 points...
Building topology for vector map <test@stuporglue>...
Registering primitives...
0 primitives registered
0 vertices registered
Building areas...
0 areas built
0 isles built
Attaching islands...
Attaching centroids...
Number of nodes: 0
Number of primitives: 0
Number of points: 0
Number of lines: 0
Number of boundaries: 0
Number of centroids: 0
Number of areas: 0
Number of isles: 0
0 points imported

lasinfo reports 12588100 points.

v.in.lidar imports only valid points. How many valid points does lasinfo report?

Markus M

I'd be happy to get this imported either through the command line or the
GUI, but my goal is to understand enough about GRASS to script the creation
of a state-wide DSM from LiDAR data.

Thanks,
Michael Moore

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Markus_Metz · February 20, 2014, 8:57pm

On Thu, Feb 20, 2014 at 2:24 AM, Michael Moore <stuporglue@gmail.com> wrote:

Hello,

I think I'm doing something wrong with importing lidar data in GRASS 7.

My data is a laz file from the state of Minnesota.

The complicating factor is that the EPSG code is set incorrectly --
EPSG:32715 / UTM 15 S instead of EPSG:26715/UTM 15 N. My region is set to
the correct 26715.

I am using the GUI, but the command that it generates is

v.in.lidar -p -o --overwrite input=/data/3542-27-22.laz output=test

The output is:

Over-riding projection check

Something is wrong here:

Importing 0 points...

because I get

Importing 12588100 points...
100%
12588100 points imported

If you compiled GRASS 7 from source, you could go to vector/v.in.lidar and run
make clean
make

and check for any errors or warnings

Building topology for vector map <test@stuporglue>...
Registering primitives...
0 primitives registered
0 vertices registered
Building areas...
0 areas built
0 isles built
Attaching islands...
Attaching centroids...
Number of nodes: 0
Number of primitives: 0
Number of points: 0
Number of lines: 0
Number of boundaries: 0
Number of centroids: 0
Number of areas: 0
Number of isles: 0
0 points imported

lasinfo reports 12588100 points.

I'd be happy to get this imported either through the command line or the
GUI, but my goal is to understand enough about GRASS to script the creation
of a state-wide DSM from LiDAR data.

You can also use r.in.lidar method=min or first convert the .laz file
with las2txt, then use r.in.xyz method=min. With the r.in.* modules,
the region should be set first, taking particular care about the
resolution. Something like

# set the region extents to the lidar point cloud extents
g.region n= s= e= w=
# align the region again to the target resolution
g.region res=<target_resolution> -a

HTH,

Markus M

Thanks,
Michael Moore

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