The Nav Surface and BAGs
Another aspect of the data processing-related research conducted at the Center involves rethinking of the final output products of a hydrographic survey. The standard chart product of selected soundings and contours does not do justice to the information content of high-resolution multibeam and sidescan sonar data. We are working on a series of new products that will better serve the mariner as well as many other constituencies. In this context, Cmdr. Shep Smith of NOAA developed the concept of the Navigation Surface as part of his thesis work when he was a student here at CCOM. The Navigation Surface is a database that maintains bathymetric data sets at full resolution and a rule base for producing a series of derived products. This single database can be the source for hydrographic (safety of navigation) products as well as products for fisheries habitat or other studies that require full-resolution data. The combination of CUBE and the Navigation Surface set the stage for another research effort, The Chart of the Future.
In support of the adoption of CUBE and the Navigation Surface into NOAA and NAVO processing protocols, the Center organized and hosted two workshops with industry, government and academic researchers to define and maintain an open format for Navigation Surface products that will ensure interoperability amongst the various vendors and agencies. In 2004, the first workshop defined the specifications for the Bathymetric Attributed Grid (BAG) Object, and obtained the commitment of many of those attending (NOAA, NAVO, CARIS, IVS, SAIC, 7C's) to provide source code and adopt the approach. Cross platform libraries for digital signatures have been built and tested and an example certificate construction and management scheme (based on HASP network dongles) has been implemented. In 2005, a DLL version of the Open Navigation Surface (ONS) library was created along with a Visual Basic support application to allow demonstration of the security principles of the ONS project in a graphical context. A second meeting of the Open Navigation Surface Working Group (ONSWG) took place in July 2005 resulting in a build-out of the source tree for the BAG and the linking of stand-alone applications to read and write BAG-format files. In addition, this meeting adopted the digital signature system for BAGs (which supports simple XML files) using both private and public keys, with encryption and thus avoiding the need for hardware tokens. The BAG library was demonstrated at the 2005 Shallow Survey Conference in Plymouth, England with trial integrations into IVS Fledermaus, CARIS HIPS, and SAIC SABER software packages. ESRI expressed interest in integrating the BAG format into their software and NOAA OCS recommended the BAG as the transmission form of data from OCS to NGDC. A website for the ONSWG has been established at www.opennavsurf.org.
Under the direction of Brian Calder, CCOM took the lead in the ONS development, providing code development, documentation and a File Specification Document for the ONS project. Calder chaired several ONS working group meetings to generate the code-base for a beta-test Candidate Release (CR) and Full Release (FR), established SubVersion software management environment, and updated a project website to support this. The CR/FR process was completed with full source-code being released in April 2006 and the initial version 1.0.1 in May 2006. Calder presented work on ONS to the IHO Technical Standards Maintenance and Development (TSMAD) working group; the BAG has been proposed for adoption as part of the IHO S-100 suite of standards for hydrographic products (i.e., the successor to S-57). Calder continues to work with David Parker of the UKHO on the development of the IHO S100 Hydrographic Data Product Standard (HDPS) and on the definition of an initial metadata strawman to be used for the upcoming UKHO bathymetric database and the S100 HDPS.
As a focal point for the broad interest in CUBE and the Navigation Surface amongst government agencies and the private sector, the Center is fulfilling one of its prime mandates of serving as a national center of focus for ocean mapping activities. In bringing these groups together, we have facilitated efficient and collaborative research efforts that meet a national need.