pointzip: Compressing PTS and PTX files as LAZ

Martin Isenburg

overview:
The pointzip.exe program can efficiently convert large 3D scans from the PTS or PTX format (produced by Leica's Cyclone and other point cloud software) into the compressed LAZ or the uncompressed LAS format. The corresponding pointUNzip.exe program can convert the compressed LAZ or the uncompressed LAS files back to the original PTS or PTX files.

When using the compressed LAZ format (which uses the LASzip compression algorithm) the reduction in file size is a factor of 5 to 15 depending on the coherency in the point order and the number of digits stored. The user has full control about the level of precision. The intensity range of -2048 to 2047 in the PTS format gets mapped to 0 4095 during compression to LAZ or LAS and back to -2048 to 2047 during decompression to PTS. Similarly, the intensity range of 0.0 to 1.0 in the PTX format gets mapped to 0 4095 in LAZ/LAS and back. This makes compression not only lossless but also produces valid and compatible LAZ or LAS files that can be imported into other software packages.

download:

  • pointzip.exe (320 KB)
  • pointUNzip.exe (304 KB)
  • example data: Inuksuk.laz (2.1 MB)

    • user feedback:

  • "Confirmed: 7GB xyzRGB PTS to 916MB LAZ and 1.95GB xyziRGB to 195MB LAZ [all rounded to mm] Great compression ratio, congrats!"
  • "Works well on larger files as well. I was able to compress a 46 GB PTS file to 3.5 GB LAZ @ mm accuracy in 73 minutes."
  • "I zipped a 3.71GB PTS file using xyziRGB parsing and mm precision. My PTS file was from a HDS7000 merged with color photography. The output file was 303MB LAZ in 5 minutes. That's a great compression rate!"
  • "A 18.3 GB PTS file compresses to 1.82 GB LAZ in 18 minutes. A 5.54 GB PTS file compresses to 0.64 GB LAZ."

    • related publications:

  • [laszip.pdf video], Martin Isenburg, LASzip: lossless compression of LiDAR data, European LiDAR Mapping Forum, November 2011.