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

[Even Rouault]

To report to https://github.com/qgis/QGIS/issues

Le 20/02/2023 à 18:48, Mike Stanton via QGIS-User a écrit :
>
> 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> 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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