What is the LAS Format?
The LAS file format is a public file format for the interchange of 3-dimensional point cloud data data between data users. Although developed primarily for exchange of lidar point cloud data this format supports the exchange of any 3-dimensional x,y,z tuplet. This binary file format is a alternative to proprietary systems or a generic ASCII file interchange system used by many companies. The problem with proprietary systems is obvious in that data cannot be easily taken from one system to another. There are two major problems with the ASCII file interchange. The first problem is performance because the reading and interpretation of ASCII elevation data can be very slow and the file size can be extremely large even for small amounts of data. The second problem is that all information specific to the lidar data is lost. The LAS file format is a binary file format that maintains information specific to the lidar nature of the data while not being overly complex.
The LAS 1.4 Specification was approved by the ASPRS Board on November 14 2011 and is the most recent approved version of the document. To download a copy of LAS 1.4 go to ASPRS LAS 1.4 Format Specification November 14 2011
[Update: July 26 2013] The lidar mapping community now has the ability to customize the LAS file format to meet their application-specific needs. The mechanism that makes this possible is the LAS Domain Profile which is a derivative of the base LAS v1.4 specification that adds (but does not remove or alter existing) point classes and attributes. For example the Topo-Bathy Lidar Domain Profile adds point classification values for bathymetric point (e.g. seafloor or riverbed; also known as submerged topography) water surface derived water surface submerged object IHO S-57 object and bottom-not-found depth. Extra Byte Variable Length Records (EXTRA_BYTES or Extra Byte VLRs) are added for pseudo-reflectance uncertainty water column depth figure of merit and processing specific flags. We anticipate the release of additional domain profiles in the future; proposed additional domain profiles should be provided utilizing the LAS Domain Profile Description Template.
Work on LAS 2.0 was previously suspended but will be restarted in the Spring of 2012.
To download copies of superseded ASPRS LAS specifications go to:
Superseded ASPRS LAS 1.3 Format Specification October 24 2010 (PDF)
Superseded ASPRS LAS 1.2 Format Specification September 2 2008 (PDF)
Superseded ASPRS LAS 1.1 Format Standard May 7 2005 (PDF)
Superseded ASPRS LAS 1.0 Format Standard May 9 2003 (PDF)
Go to www.lasformat.org to register for a unique LAS key.