blast2dem overflow?

[Mattias Nyström]

I tried to create a DEM using blast2dem with the following commandline:

D:\_Laserdata\>blast2dem -cores 7 -use_tile_bb -keep_class 1 4 -step 1 -elevation -merged -i *.las -o 140914_chm.tif -odir chm -verbose

I then get the following message. The FATAL ERROR, can that be because of too large dataset? The tif-file created is empty...

WARNING: no tiling information. ignoring '-use_tile_bb'. maybe '-use_orig_bb' ...?

terrain finalization (using 2d quadtree) to level 11 with empty 0.

have bounding box. first pass not needed.

second pass: populating finalization counter grid ...

second pass: done. created 2074972 leaf grid cells and stored 2074972 sprinkle points

spfinalizer: needed 720.496 seconds

created parent grid cells (new total is 2773062 cells)

third pass: using finalization grid to spatially finalize 2137260907 points...

output precision is float ...

lower left x unspecified. setting it to 414100.

lower left y unspecified. setting it to 6.47789e+006.

ncols was unspecified. we set it to 9948.

nrows was unspecified. we set it to 9375.

FATAL ERROR: vertex not in hash. need pre-order mesh

third pass: done. stored at most -1968121012 chunked points (plus 2074972 sprinkle points)

spfinalizer: needed 4110.91 seconds

duplicate_points 118480586

spdelaunay2d: needed 4110.67 seconds

read 2137260907 points. produced TIN with 2018780321 vertices and -257406718 triangles

took 4835.42 sec to create 'chm\140914_chm.tif'.

[Martin Isenburg]

Hello,

currently the max point limit for BLAST is 2 billion points and you
seem to be slightly above that limit. Looks like I need to remove that
limit soon. It always seemed that 2 billion points would be enough for
a long time ... (-:

Martin @rapidlasso

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[Mattias Nyström]

Thanks for your reply. This is a rather small area (15 km2), but very the ALS is very dense. Looking forward for a "unlimited" version :)

//Mattias

[Jon Moe]

Hi Martin,

did you get around to make the limit higher for blast2dem? I think that I'm still bumping in to this issue with 2.3 billion points total in the project. (no files with more that 5 million points)

blast2dem -i *.laz -rgb -step 5 -odir rgb -o rgb_5x5.png -merged -scale_rgb_down 

I tried using the tiled files with las2dem, but would get 1m white stripes between the tiles that mess with my later workflow.

Jon

[Martin Isenburg]

Hello Jon,

I have not yet. Also because its just so much more efficient to use a tile-based workflow. If you get white stripes between the tiles you are probably not doing the tile processing correctly with buffers:

http://rapidlasso.com/2015/08/07/use-buffers-when-processing-lidar-in-tiles/

Also I notice that you use a step size of 5 meters. How dense are your points? Maybe you can simply downsample your input points to a resolution that is more suitable for producing rasters of 5 meter pixels size:

blast2dem -i *.laz ^

                 -merged ^

                 -thin_with_grid 2.5 ^

                 -step 5 ^

                 -rgb -scale_rgb_down ^

                 -odir rgb -o rgb_5x5.png

or

lasthin -i *.laz ^

           -merged ^

           -step 2.5 ^

           -central ^

           -o temp.laz

blast2dem -i temp.laz ^

                  -step 5 ^

                  -rgb -scale_rgb_down ^

                  -odir rgb -o rgb_5x5.png

Regards,

Martin @rapidlasso

PS: Want to meet rapidlasso GmbH in person and talk LiDAR, photogrammetry points and LAStools? See our upcoming event schedule here: http://rapidlasso.com/events