The "Thin LiDAR Line of DEATH!!!"

[kdjacob]

I'm relatively new to CloudCompare.

I'm running CC 2.13.2 on a MacBook with Apple Silicon M1. Attachment 0 is a screenshot with more exact info on my build.

Attachment 0.jpg (31.51 KiB) Viewed 7192 times

I've been successfully downloading .laz files from two sites: NOAA and USGS (see links below).

The .laz files from USGS load beautifully into CC but the files from NOAA result in the "Thin Line of Death" (Attachment 1).

Attachment 1.jpg (41.55 KiB) Viewed 7192 times

There are multiple threads about this issue from others, and it seems from reading other threads that the NOAA files are doing this because of their spherical coordinates when CC wants cartesian coordinates. In Attachment 2 it looks to me like the X and Y are in degrees and Z is a length, which probably confirms the source of the problem.

Attachment 2.jpg (139.62 KiB) Viewed 7192 times

I've tried a number of ways to convert the NOAA files into something that uses a cartesian CRM -- like converting to UTM in QGIS -- but nothing I've tried has worked.

In Attachment 3 and Attachment 4 I show the results of running two files (one from NOAA and the other from USGS) through LAStools lasinfo, in case that information might be helpful.

I would appreciate any advice on how I might go about fixing this problem?

Thanks,

Ken


USGS Site: https://apps.nationalmap.gov/lidar-explorer/#/
NOAA Site: https://coast.noaa.gov/dataviewer/#/lidar/search/

[daniel]

It's probably because the coordinate system is not a Cartesian one. It's probably a geographic CS with X and Y being angles while Z is metric and has a very different scale.

[kdjacob]

Hi Daniel,

Yes, that appears to be the issue.

Are there workarounds you can suggest?

And given the source (NOAA) isn't this an issue encountered by many users?

I put this in as a "bug" in Github but that may be a mischaracterization if there's an obvious workaround.

Ken

[daniel]

I guess you can use GDAL to convert the points from one coordinate system to the other? (or any GIS).

[kdjacob]

I've recently added to my post in Github with the hope that someone can help fix this problem.

These standard point cloud files from NOAA are unusable at this point.

(Tried changing coordinate systems in QGIS but that program doesn't like these files either.)

Strange.

Ken

[Pointdump]

Hi Ken,
Have you tried las2las in lastools?
Dave