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The LiDAR industry is benefitting from many of the IT industry’s hardware advances–processing speed, throughput, sensor resolution and sensitivity, laser modulation, reductions in size and energy demands of components. Unfortunately, it can’t take full advantage of many software advances such as Web services, apps, and the cloud, because it lacks a framework of open communication standards.
Information technologies thrive when they can connect with other technologies in useful ways, combine data from different sources, and establish connections to both established resources and innovative new services. Thus the potential benefits of LiDAR are not being fully realized.
The Internet is the paradigmatic "open connector" of digital resources. The Web is descended from the Internet, and many families of open standards are descended from the Web’s open standards: http, xml, and WMS. Openness is the main reason for the abundance delivered by this technology family tree.
LiDAR is a 3D spatial technology. It serves humans’ needs to represent surfaces in built and natural environments, which are inherently geo-spatial. LiDAR potentially provides a valuable complement to other spatial digital technologies, but this happens only as LiDAR data is fused with other representations of spatial features and phenomena.
Almost 20 years have passed as players in other spatial technology domains have been working together to develop a platform of open spatial standards. Much of the platform is now in place. Fortunately, because of lessons learned, standards processes that have been established and the "hooks" that are provided, it could take the LiDAR industry much less time to reach the same level of open standards maturity as GIS, Earth Observation and Sensor Webs.
Current trends and events make the present time a fortuitous one for this collaboration to begin. The Internet of Things is just beginning to take off and drive new standards. The Open Geospatial Consortium (OGC) has been building a network of "Alliance Partner" organizations, many of them standards development organizations (SDOs) in market domains that are now served, or will be served by LiDAR providers. The sooner the LiDAR industry provides technical representation in appropriate SDO Technical Committees and Working Groups (not only in OGC!), the more rapidly the industry will get standards and standards-related best practices that meet the LiDAR industry’s communication requirements.
The current state of LiDAR standards: formats
A number of LiDAR data formats/ specifications are currently in use:
The US National Geospatial Program (NGP) worked with federal and private sector partners to develop a document that has become the foundation of LiDAR specifications worldwide and has been adopted widely in U.S. Federal agencies. This is the NGP LiDAR Base Specification Version 1.0 or "the v13 Spec." (http://pubs.usgs. gov/tm/11b4).
The High Resolution Elevation Format (HRE) is used by US National System for Geospatial Intelligence (NSG) partners.
The binary LAS file format, currently maintained by the ASPRS as a standard file format for airborne laser scanning, was developed to store airborne LiDAR laser points and its attributes. ASTM E57 is a standard 3D data exchange format. It has a XML component. The XML foundation is important, because it opens up the possibility of open interfaces for software that can recognize and parse LiDAR data and communicate with other software components with similar read/write capabilities. An XML encoding, however, would need to be designed for compatibility with other widely used and open XML-based spatial encoding standards (particularly GML, the OGC Geography Markup Language Encoding Standard) to provide maximum interoperability in the world of spatial processing.
A full review of the various LiDAR data formats is beyond the scope of this article, but the thing to remember is that even if there were only one format, the industry would still need a way for web services to communicate the results of a scan.
Successful LiDAR integration experiments in OGC’s 2012 OWS-9 Testbed Activity
Professionals that use point clouds would save a lot of time if they didn’t need to copy, store and process these huge files, but could simply get access to them on the cloud, via the web. If a point cloud were hosted on a high performance cloud server, the server could receive and respond to a variety of requests for information that the server could extract from specified regions in the point cloud. The information product might be a 3D surface represented as polygons, for example, or a raster-based digital terrain model. With open service interfaces, the information product might be the result of a series of processing steps–chained services–executed by servers hosted in different parts of the cloud. Some of these services would be "fusing" LiDAR-extracted data products with spatial data from other sources.
The OGC Web Services Activity Phase 9 (OWS-9) Testbed included a number of different technology "threads" One . topic area in the OWS Innovations thread, Coverage Access and Data Quality, looked at the suitability of a number of different data formats, including LiDAR HRE data, for integration into an OGC Web Services environment. The experiments included data encoded in the US NITF (National Imagery Transmission Format) and the OGC GML in JPEG 2000 for Geographic Imagery Encoding Standard. These experiments showed that LiDAR data can indeed be brought into the OGC standards framework for integration with other kinds of spatial data. More standards work remains, however.
Looking ahead
Looking at global growth of cities and upward-trending mass markets such as Virtual Reality, smart glasses, inexpensive UAVs, and indoor/outdoor urban models in the cloud, it is apparent that LiDAR will play an increasingly important role. To be valuable, however, LiDAR data needs to be fused with other kinds of data–Lat/Lon, CAD, Civil Engineering, 3D models, Building Information Models, 2D images, GIS, Virtual Reality, navigation and more. The OGC experiments show that the LiDAR industry can realize the service chaining and data fusion vision described above. This is encouraging, but LiDAR and other spatial technologies are complex, and so more testing, demonstrating and consensus-building must be accomplished before LiDAR can become an easily-integrated spatial resource.
LiDAR industry players need to evaluate LiDAR standards requirements and explore the larger standards world to see where their efforts will do the most good. New standards and new best practices for the use of existing standards need to be developed. Some of this standards work will necessarily occur in the OGC, but some of the work will necessarily occur in other SDOs.
The OGC collaborates with SDOs in domains such as CAD, Civil Engineering, 3D modeling, and Building Information Models because many spatial information applications require an integrated indoor/outdoor information environment. The LiDAR industry will surely benefit from this collaboration, but specific LiDAR industry requirements will probably not be addressed by accident. Without LiDAR industry representation, standards for Augmented Reality or indoor navigation, for example, could favor other ways of capturing information about surfaces.
The OGC’s memoranda of understanding with other SDOs are a necessary but not sufficient condition for standards coordination. It is the members of these organizations who do the actual work. Sometimes it is not enough to participate in one technical committee or working group. To bridge technologies, technology providers need to assign engineers who participate in each of two SDOs’ technical committees or working groups. These are the people who prevent standards silos and discourage the parallel emergence of competing standards that confuse and inhibit markets.
Developing interfaces and encodings in a consensus standards organization ultimately saves money for technology providers, because they can share the costs of developing technology they would otherwise develop alone, and often repeatedly, for different technology environments. Also, consensus standards organizations typically include technology user organizations as well as technology providers, and so membership provides unmatched opportunities for networking with potential customers and staying abreast of market developments.
The OGC serves as a global forum for the collaboration of developers and users of all kinds of spatial data products and services. Efficient integration of LiDAR with other spatial technologies would benefit providers of LiDAR products and services and also a broad range of other stakeholders.
Bart De Lathouwer is Director of interoperability Programs for OGC, and is responsible for planning and managing interoperability initiatives such as testbeds, pilot projects and interoperability experiments with an emphasis on activities in Europe.
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