LIDAR Format Letter

=Open Letter for the need for Open Standards in LiDAR= March 2015.

We, the undersigned, are concerned that the current situation, where there is a defacto industry standard for storing LIDAR data, is being threatened by ESRI's introduction and promotion of an alternative closed format.

This is of concern as it reduces interoperability between applications and organisations, and introduces vendor lock-in.This has also wider implications in Geo education, various government policies on Open Standards, Procurement etc.

We request that:
 * 1) The OGC initiate the formalisation of an open standard for storing LIDAR data, and OGC sponsors prioritise a LIDAR standard in sponsorship priorities.
 * 2) Users and sponsors of LIDAR data, and the LAS Working Group (LWG) which is part of ASPRS, publicly state their preference for the use of an open format over closed when selecting software and services.
 * 3) ESRI join efforts to support agreement around an open LIDAR format.

=Signed= Name, Affiliation(s), Optional comment on interest in Open LIDAR format


 * 1) Suchith Anand, Geo for All , committed to Open Principles in Geo Education and Policy.
 * 2) Cameron Shorter, GeoSpatial Manager at LISAsoft, Co-coordinator of OSGeo-Live, Contributor to numerous OGC testbeds, technical lead on a number of previous Australian and New Zealand Open Government initiatives.

=Background=

About LIDAR
LIDAR (Light Detection and Ranging) is a form of high precision range detection much like a radar system that uses laser light as the electromagnetic emission. One of LIDAR systems’ products is a “point cloud” data product that can be conceptualized as a series of point measurements representing distance from the sensor to a returned emission. A common storage format for these point cloud data is the LAS format.

To date, [March 2015] there has been a common format for storing LIDAR data, the “LAS” format, and an open source library, libLAS, that can read and write the format. Rather than write their own format support, most vendors have simply used libLAS, and the LAS format has become an industry standard.

LAS limitations
Quoting Paul Ramsey:


 * LAS format is not without its drawbacks:


 * While it is a binary format and does not waste any space unnecessarily, neither does it apply any compression to the data it stores. That’s not good for archival use.
 * Also, LAS stores points in scan order, so accessing any particular chunk of points involves reading the whole file. That’s not good for random access.
 * Clearly there is a little more work to be done. Can LAS be improved? In fact, it already has been:
 * An open source compression library LASzip can apply 20:1 lossless compression to LAS files, making them great for archival purposes.
 * Other LAS users have experimented with re-ordering points in a LAS or LASzip file to allow random access to internal chunks of the LIDAR point cloud.
 * Basically, making LAS smaller and faster is not rocket science, and if the work were incorporated into libLAS then the whole LIDAR community could leverage it together, and the user community would only have one file type to interchange.

Closed "Optimized LAS" format from ESRI
ESRI has announced the release of an Optimized LAS format which is claimed to provide faster access and smaller file sizes. ESRI has also released a free tool which is claimed to convert LAS files to and from Optimized LAS.

However, the Optimized LAS format is not published, or available under an open license, which provides both technical as well as legal barriers to other applications reading and/or writing to this proprietary format. This creates a vendor lock-in scenario which is contrary to the principles of the Open Geospatial Consortium, the OSGeo Foundation, and many government IT procurement policies.

OGCs efforts so far to enable Open standards in LiDAR
Carl Reed provided the following information on OGC's efforts so far to work towards enabling Open Standards in LiDAR.
 * "Over the last 8 or so years, the OGC approached ASPRS at least twice regarding LAS and working with ASPRS to bring LAS into the OGC for consideration as both a Best Practice and an OGC standard. There was an OGC member Rock Pearsall who worked hard to try to make this work. Rick worked for NGA, was active in the OGC, and was also the Standards Committee chair at ASPRS. Rick and Carl tried and failed. These attempts go back to at least 2007.http://www.asprs.org/a/society/divisions/ppd/ppd_meetings/2007springppdreport.pdf. More recently,  Carl Reed had an email dialogue with Lewis Graham about bringing LAS into the OGC as an OGC Best Practice. Carl thought progress was being made, but then for some reason all communication stopped."

=Importance of Standards=

The importance of Open Standards is described is most government IT policies. For instance, the United Kingdom policy states:
 * … Government assets should be interoperable and open for re-use in order to maximise return on investment, avoid technological or supplier lock-in, reduce operational risk in ICT projects and provide responsive services for citizens and business. This should also lower barriers to entry for more diverse sources of IT services, including citizens and SMEs.


 * TBD: Is there an OGC reference we can add here?


 * TBD: Explain why standards are important to education, preferably by referencing an education policy or similar.

=See Also=
 * 1) Paul Ramsey provides background to LAS vs Optimised LAS, http://boundlessgeo.com/2014/01/lidar-format-wars/
 * 2) Running commentary by Martin Isenburg, author of LibLAS, http://rapidlasso.com/2015/02/22/lidar-las-asprs-esri-and-the-laz-clone/
 * 3) ESRI Announces "Optimised LAS", http://blog.lidarnews.com/esri-announces-las-compression/
 * 4) ESRI description of "Optimised LAS", http://www.lidarnews.com/content/view/10214
 * 5) Discussion background on this topic at Geo for All list, http://lists.osgeo.org/pipermail/ica-osgeo-labs/2015-March/001225.html