Often I get asked about the difference between las2dem.exe and blastdem.exe – the latter being part of the BLAST extension of LAStools. In the academic video from 2006 below, I outline the core technology details behind BLAST, which can seamlessly compute gigantic Delaunay Triangulations from billions of LiDAR points – using very little main memory. The blast2dem.exe module does not store the gigantic TINs that BLAST produces, but immediately rasters the finalized triangles streaming out of BLAST into equally massive DEMs. This avoids to ever having to store such huge triangulations – that are only needed temporarily – to disk. Currently blast2dem.exe can “only” process up to 2 billion points per file – a limitation that shall be lifted soon.
April 26, 2012
rapidlasso consulting, Sommerhausen, Germany
Here is a video of my talk at ELMF 2011 on “LASzip: lossless compression of LiDAR data”.
Airborne or mobile laser scanning technology (LiDAR) collects billions of xyz points that are typically stored in the LAS(er) format. LASzip is a lossless compressor to turn large LAS into smaller LAZ files. Encoding and decoding speeds are 1 to 4 millions points per second and compressed files are only 7 to 25 percent of the original size.Compression and decompression happen on-the-fly in a streaming manner and random-access is supported. A reference implementation unencumbered by patents or intellectual property concerns is freely available with an LGPL-license here.