[Qgis-user] Two LAZ file possible issues iwth some new data we received to processs

[Mike Stanton]

Hi Nicolas, thank you for the well researched and detailed answer.  I was running on the latest build and it had a the new feature for Cloud Optimization COPC.  That feature doubled the number of open files for the process and I dropped back to 3.22 to get my processing done. It appears that during the indexing process  of 3.28 the COPC files are left open even after moving on to another LAZ file.  The 3.22 level did not create the COPC files and everything worked out for the images.

From: Nicolas Cadieux <njacadieux.gitlab at gmail.com>
Sent: Friday, February 17, 2023 7:20 AM
To: Mike Stanton <mfstanton at geospan.com>
Cc: qgis-user at lists.osgeo.org
Subject: Re: [Qgis-user] Two LAZ file possible issues iwth some new data we received to processs

Hi,

I did run into this layer number limite in the past.  If you check the user list or if you Google “QGIS, maximum amount of layers… “ you will find multiple post. The issue, at the time was caused by limites in the OS.  (Windows 7 at the time), OSX had and easy work around.  Same thing for the various flavours of  Linux.

At the time, I either combined files when using QGIS or opened them in Saga that did not have this problem. I believe this was  because Saga, at least back then, loaded all the file into memory and did not keep a handle on the files once is was open.

This is the type of thing that got me into learning Python so that I could create loops and speed up operations on LiDAR data.

It’s normal (or at least expected)  for large batches of file to have bugs in them like missing crs in headers.  File transfers can be difficult to handle.  Talk with the provider to see if they have the same issue.  If you know a bit of Python, I could send you a script that reads the LiDAR header directly.

LasPy is a good little library for this https://laspy.readthedocs.io/en/latest/intro.html#header

You could find tools in WhiteboxTools also.
Nicolas Cadieux
https://gitlab.com/njacadieux


Le 16 févr. 2023 à 17:50, Mike Stanton via QGIS-User <qgis-user at lists.osgeo.org<mailto:qgis-user at lists.osgeo.org>> a écrit :

I have LAZ files  for a square mile of the local area where my office is and when it is loaded under QGIS I hit two problems. It is a bit over 2000 files and I seem to have hit a capacity limit where it stops processing the images at about 200 files.  The message being output for the files is “Failed to Calculate Statistics of the Point Cloud of XXXXXXXXXXXX.LAZ”.   Breaking it into smaller pieces gets the project around the scale limits of the product because the doing only the rejected files gets me more files processed, but it is not convenient considering I expect to be processing a lot more of these files.

The other problem is that QGIS tells me I don’t have a CRS for the images and the image has a field that says “No CRS Found” in the log file and what I have is data in the header that says “COMPD_CS [“Projected”, PROJCS “UTM 15N”, GEOGCS [WGS84 …. “  but the strings have unpaired square brackets round the relevant text. Is this what may be causing the error to occur?
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