[GRASS-dev] Memory use in v.in.lidar for points with attributes

[Moritz Lennert]

On 22/07/16 16:05, Newcomb, Doug wrote:
> Hi Folks,
> My goal is to import a LiDAR point cloud from an LAS file with 152
> million points.  I would like to use v.lidar.mcc to extract bare earth
> points from the point cloud for generating a DEM  However, v.lidar.mcc
> requires that the point layer have an attribute table

Are you sure ? The example in the v.lidar.mcc man page says:

v.in.lidar -tr input=points.las output=points
v.lidar.mcc points ground=ground_points nonground=non_ground_points

the -t in v.in.lidar means "Do not create attribute table".

 > rather than just
 > the raw x,y,z points without topography.

Do you mean topology ?

Attribute table and topology are two seperate issues.

>
> So using v.in.lidar, I am importing  the lidar points as normal points,
> and the memory usage is steadily climbing.  Less than 1/4 of the points
> are imported and memory usage is at 5GB . This on a Windows 7 64 bit
> system with GRASS 7.2 svn
>
> I'm suspecting this is not the expected behavior.

I would say that it is expected. YMMMV with different database backends, 
but attribute handling can be memory-heavy.

What does v.in.lidar -t give you ?

If some attribute really need to be conserver, maybe this a good case to 
test Vaclav's additions to v.in.lidar, storing attributes as cat values, 
instead of attributes in a table:

https://lists.osgeo.org/pipermail/grass-dev/2015-September/076490.html
https://trac.osgeo.org/grass/changeset/66343

Moritz