LIDAR Format Letter

Open Letter for the need for Open Standards in LiDAR

March 2015.

We, the undersigned, are concerned that the current interoperability between LiDAR applications, through use of the open "LAS" format, is being threatened by ESRI's introduction and promotion of an alternative "Optimised LAS" closed format. This is of concern as it reduces interoperability between applications and organisations, and introduces vendor lock-in.

We request that:

1. The OGC initiate the formalisation of an open standard for storing LIDAR data, and OGC sponsors prioritise the development of this LIDAR standard.
2. ESRI support the OGC in their mission "to advance the development and use of international standards and supporting services that promote geospatial interoperability." In particular, join the OGC in developing of an Open Standard for use of LIDAR data. This might include proposing ESRI's "Optimised LAS" as an Open Standard, and removing technical and legal hurdles to use of "Optimised LAS" as an Open Standard. A simple test to determine if "Optimised LAS" can be used as an Open Standard would be if "Optimised LAS" can legally be implemented by Open Source software such as LibLAS or LASzip.
3. 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.

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. This libLAS library has been incorporated within many LIDAR applications, allowing read/write access to the common "LAS" format, and with resulting interoperability between these applications.

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. OGC member Rick Pearsall 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."

There is current interest by the OGC in pursuing point cloud encoding standards, including a member-initiated mechanism to extend LAS data with OGC-standard XML content. The OGC invites interested members who wish to work on this effort to please contact Scott Simmons (Executive Director, Standards Program E-mail : ssimmons@opengeospatial.org ) to register their interest and discuss details. OGC will also be holding an ad hoc session at our next Technical Committee meeting in Boulder, CO, USA in early June to bring together all interested from all sectors (government, industry, academia) for this and plan next steps.

Attempted community engagement in development of Optimised LAS

TBD: Martin Isenburg (and possibly OGC members?) to add history in the development of the Optimised LAS format.

• Highlight community attempts to work collaboratively with ESRI. How did the community reach out? How did ESRI respond?
• It might make sense to merge the "OGC efforts" section and this section under one "History" heading.

Value 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.

The value of Open Standards have been described in numerous national studies on the effects of standards on economic growth.

... the national studies demonstrate that standards have a positive influence on economic growth due to the resulting improved diffusion of knowledge. The contribution of standards to the growth rate in each country is equivalent to 0.9% in Germany, 0.8% in 0.3% in the UK and 0.2% in Canada.

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. Earlier comment from Martin Isenburg, http://rapidlasso.com/2014/11/06/keeping-esri-honest/
4. ESRI Announces "Optimised LAS", http://blog.lidarnews.com/esri-announces-las-compression/
5. ESRI description of "Optimised LAS", http://www.lidarnews.com/content/view/10214
6. Discussion background on this topic at Geo for All list , http://lists.osgeo.org/pipermail/ica-osgeo-labs/2015-March/001225.html