1. 2004-05-23Open Navigation Surface Working Group CHC2004 Uncertainty Workshop 1 The Open Navigation Surface Model Brian Calder Center for Coastal and Ocean Mapping & NOAA-UNH Joint Hydrographic Center

2. 2004-05-23Open Navigation Surface Working Group CHC2004 Uncertainty Workshop 2 Open Navigation Surface Community response to concerns for inter- operability of data products Intent: –Define a concrete representation of the Navigation Surface data model –Identify software technologies to support and implement the data model –Provide a free, open source code-base as a reference implementation Hosted by CCOM as a vendor-neutral third party

3. 2004-05-23Open Navigation Surface Working Group CHC2004 Uncertainty Workshop 3 Open Navigation Surface Working Group Started by e-mail solicitation of statements of interest –Technical:navsurf_dev@ccom.unh.edu –General:navsurf_general@ccom.unh.edu Core group formed by responses from: –CCOM, NOAA, NAVOCEANO –IVS, CARIS, SAIC, 7Cs First meeting held 21-23 January 2004

4. 2004-05-23Open Navigation Surface Working Group CHC2004 Uncertainty Workshop 4 Goals of the ONSWG Determine the requirements for an Open Navigation Surface data object, specifying all of the mandatory data elements. Determine suitable software technologies to implement these requirements Develop one or more source-code libraries that form a reference model for reading and writing data in this format, and provide support and guidance to potential users

5. 2004-05-23Open Navigation Surface Working Group CHC2004 Uncertainty Workshop 5 Format Requirements A new name –“Navigation Surface” means different things to different people –Adopted “Bathymetric Attributed Grid” (BAG) for the data elements used to make navigational products –Reserved “Navigation Surface” to mean a BAG which has actually been made for a specific navigational purpose Meta-Data –Meta-data to include everything of interest that has happened to the data (e.g., processing, certification for navigational use, etc.) –Meta-data to be in XML using ISO19139 encoding to ISO19115 content standards –Meta-data to be kept in the same file as the data to avoid loss in transit

6. 2004-05-23Open Navigation Surface Working Group CHC2004 Uncertainty Workshop 6 Format Requirements Mandatory Data Components –Elevations on a regular grid at a single resolution (may be different in x,y) –Associated uncertainty on a co-located grid –Special exceptions (human over-rides) Extension Data Components –Arbitrary ‘other’ data (grid or non-grid) as required by particular users –Must remain open (reviewed by ONS architecture board), non-proprietary –Procedures documented in Format Specification Document (BAG-FSD) [All grids are single-resolution node-based objects, but can be geographic or projected, and are reduced to one of a number of vertical datums; SI units are used throughout, with a right-handed coordinate system (z is positive up)]

7. 2004-05-23Open Navigation Surface Working Group CHC2004 Uncertainty Workshop 7 Format Requirements Certificates and Digital Signatures –Every BAG will be hashed to the Secure Hash Standard (FIPS 180-2) –Every BAG will be digitally signed by the Digital Signature Standard (FIPS 186-2) to ensure taper-detection and authentication –Signing a BAG requires an entry in the XML meta-data indicating who did the signing, and what the certification implies for the data. Documentation –Defined by Requirements, BAG-FSD and BAG-API –Intended to be living documents in CVS control Advisory Board –Intended to review new modifications and requests –Co-opted by invitation, defined in BAG-FSD Platform Independence

8. 2004-05-23Open Navigation Surface Working Group CHC2004 Uncertainty Workshop 8 BAG Format Outline Overall Metadata Depth Certification data Meta- data Uncertainty Meta- data Change-Tracking List Meta- data Extensions (Optional) Meta- data HDF-5 Data Object Mandatory

9. 2004-05-23Open Navigation Surface Working Group CHC2004 Uncertainty Workshop 9 Progress and Current Status Technologies Identified: –HDF-5 (1.6.1), zlib 1.1.4, szip 1.1 –libgcrypt-1.1.44, libgpg-error-0.6 –Geotrans 2.2.3 (NGA) –XML parser TBD, possibly Apache Xerces CVS Code/Documentation Repository Established –Open, but not public, access –Hosted at CCOM/JHC (brc@ccom.unh.edu) Documentation at V1.0 for BAG-FSD, BAG-API Test code built for sub-components and checked in; operation confirmed on Linux and Win32

10. 2004-05-23Open Navigation Surface Working Group CHC2004 Uncertainty Workshop 10 Summary The Open Navigation Surface is a file format specification known as BAG –Provides method for transfer of data –Provides enough flexibility for processing too The project is supported by the community for the community –Provides for open-source code-base libraries –Based on ‘standards’ where possible A BAG consists of: –Depth, Uncertainty and Change-tracking List for a single bathymetric entity –Meta-data describing the data, including processing –Certification for authentication, tamper-detection –Optional extension elements for specific purposes

11. 2004-05-23Open Navigation Surface Working Group CHC2004 Uncertainty Workshop 11 Taking Part! Membership is open to all interested parties –Consists of willingness to be involved –Send e-mail to brc@ccom.unh.edu Interact via the mailing lists: –navsurf_dev@ccom.unh.edu for technical details of development, API and format coding –navsurf_general@ccom.unh.edu for administrivia, policy and higher-level discussion –Send e-mail to brc@ccom.unh.edu to be added Contribute code, time, enthusiasm (as available)

12. 2004-05-23Open Navigation Surface Working Group CHC2004 Uncertainty Workshop 12 Thank You To: CCOM/JHC:Brian Calder, Rick Brennan, Lee Alexander CARIS:Bill Lamey IVS:Mark Paton SAIC:Shannon Byrne, Jim Case NAVO:Dave Fabre, Wade Ladner, Jan Depner NOAA:Barry Gallagher, Jack Riley, Shep Smith, Rick Brennan SevenCs:Friedhelm Moggert … and the supporting institutions for time, travel & expenses.