Extracting descriptive information from a LiDAR cl

问题:

I have .las (lidar data) file, now I wanted to know the size of it, for example how long it's width and height in kilometers.

How is it possible to retrieve these kind of info?

回答1:

tl;dr: install libLAS and run lasinfo myfile.las.

Lasfile headers, in general, shouldn't be trusted since they may not agree with the true data bounds. A more robust approach is to calculate the spatial extents of the data by reading the points themselves. Here's a few free and open-source ways to calculate the true bounds of a lasfile:

• libLAS, via lasinfo mylasfile.las
  • libLAS can also be compiled with LASzip support to read .laz files
• PDAL, via pdal info myfile.las
  • PDAL can also be configured to read other types of pointcloud files, including compressed .laz and more
• If you want to inspect the lasfile's extents (and other properties) programically with Python, you can use laspy

Many of these software projects are available via package managers for your system:

• Windows: OSGeo4W includes libLAS, LASzip, and PDAL
• Ubuntu: sudo apt-get install liblas-bin will install lasinfo on Ubuntu 14.04, 12.04, and others
• OSX: brew install pdal liblas using Homebrew
• laspy can be installed via pip install laspy

回答2:

You best bet is to use a specific software to find out the extent of this lidar file.

Another way you can probably do it is to look at the header section of the file (if you have the raw file), which must state the extent as well.

Otherwise, talk to the data provider (if you can´t find out the extent any other way). He probably has the software and knows the extension of your dataset.

George

回答3:

You can use the lasinfo utility from lastools which will return the .las header information (including the extent):

http://www.cs.unc.edu/~isenburg/lastools/

The lasinfo module in SAGA GIS will provide the same information:

http://www.saga-gis.org/

回答4:

With Fusion, an option is the command line Catalog to retrieve descriptive statistics.

Suppose Fusion is installed under the directory c:\fusionand the las file is stored in c:\lidar\point_cloud.las. Write and run:

c:\fusion\catalog c:\lidar\point_cloud.las c:\lidar\point_cloud

An output example is:

Add switches to obtain more information or to adapt the command to specific needs (e.g.; switch 'coverage' will show nominal coverage area of the entire lidar cloud).