Global Mapper v25.0

las-file import

jmhacker
jmhacker Global Mapper User
edited February 2009 in Technical Support
I am trying to import Lidar las files into Global Mapper anf have a few questions:

If I am answering "NO" to the question about creating a surface for the imported file, the program imports the file, and displays it as a point cloud. When I then tell the program to generate a surface later, it does not ask, if it should use ground shot points only, although the las-file contains the fields for classification of the returns.

If I answer "YES" to the initial question and tick the box "Only use ground shot points", the program hangs itself up, showing the "Loading" window with the progress bar sitting at about 50%.

If I answer "YES" to the initial question and un-tick the box "Only use ground shot points", the program imports data and generates a surface, but obviously containing all returns.

The files are about 27Mb and contains 1,000,000 points, not a lot for a lidar data sets, and they are in las-format 1.1 .

I put one of the las-files I am trying to import onto our server at www.naers.org/ARA/GM/example.zip, in case you would like to try yourself. The relevant UTM-sone is -53 (near Alice Springs/Australia).

So the questions are:

* why does the program hang itself up ?
* why is the question about using ground shot points only not being asked, when surfacing the data later ?

My best guess is that GlobalMapper somehow does not recognise the classification in the las-file.

Thanks for your help in advance.
Jorg (I am a registered use of GlobalMapper Version 10.01 - not sure, if you need my registration code to reply).

Comments

  • global_mapper
    global_mapper Administrator
    edited February 2009
    Jorg,

    I took a look and found that the program wasn't actually hanging up when you checked the option to only use ground shot points, it was just using a very slow (but very memory efficient) approach to remove the non-ground shot points. I have updated this to use a much faster approach and show you progress. I have placed a new build at http://www.globalmapper.com/global_mapper10.zip with the change for you to try. Simply download that file and extract the contents into your existing v10.xx installation folder to give it a try.

    You might also note that you can easily disable the display of various Lidar types using the Point Filter setting on the Vector Display tab of the Configuration dialog. You could use this to turn off everything but ground shot points and then generate your grid after loading as a point cloud to achieve the same results.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • jmhacker
    jmhacker Global Mapper User
    edited February 2009
    Mike,

    Many thanks for your lightning-fast reply. Yes, it works.

    Best regards,
    Jorg.