I have been using the LIDAR .laz data for several months. I have found that it is susceptible to transmission errors. Sometimes, I have had 3 out of 4 files which were transmitted that were corrupted. I use las2txt.exe to transform the laz data files to xyz triplets. After 'gridding' the xyz data...the resulting maps were corrupted up to 75% of their coverage.
At first, I thought that the original LIDAR data files might have been corrupt or that las2txt was generating errors. But after running las2txt over several additional files and
it translated the data perfectly...I knew that las2txt was running correctly!
I then had the files retransmitted to me...this time the translation...gridding...mapping worked as it should. Looking at the first transmission file size compared to the second try...the files were of different sizes.
So, if you get what appears to be bad LIDAR maps. Go back and have the same files downloaded to your site and try again.
The file sizes were nearly the same, so you won't be able to tell if there is a problem until you look at the finished map.
Is anyone else having this problem?
The only thing that seems likely to me if the files were close to the correct size is the Ascii/Binary switch on command line ftp which in Windows (and nothing else that I know of) defaults to A. Most other ftp clients are clever enough to guess correctly on the file type, or they just use Binary and don't worry about line termination character differences.
Otherwise, the transmission protocols tend to be robust enough to make errors extremely uncommon.
If anyone else is seeing this I'd be interested in checking our logs for the downloaded file to see if there is anything unusual there.
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