n Location intelligence

LOCATION INTELLIGENCE

DATA PROVENANCE IS ESSENTIAL IN ASCERTAINING CORRECT GEOSPATIAL INFORMATION.

The ‘belt and braces’ approach to navigation: ‘Never rely on a single positioning source on its own’ and ‘How to get your position very precise and completely wrong’ are two major learning points from my professional career in the geospatial industry to date. The premise of these learning points can be summed up in another learning point from military intelligence practice: information is not intelligence until it is processed and validated against other information and other sources. When it comes to geospatial information, data provenance facilitates validation and is vital in order to add user confidence to the process of turning information into intelligence.

FEATURE

Gary Delaney Geospatial forensic analyst, Global Position Intelligence (GPI) Nowadays, we hear a lot about ‘location intelligence’, but very little about what makes the spatial data intelligent in the first place, i.e., its provenance. When available, this information can be used to determine suitability for purpose and confirm the kind of intelligence that can be reliably determined from the information. Geospatial data provenance is well understood in professional navigation practice, where information accuracy is a real-time and safetycritical consideration. As someone who has navigated ships in confined situations, taught navigation to Master Mariners, worked on precise geodetic projects, and prepared geospatial evidence for legal cases, I can assure that informed ownership of the provenance of geospatial data is what convinces a jury and keeps ships, aircraft and human beings safe. It also prevents disputes and saves on cost. It is what turns information into location intelligence, including in landbased geographic and geodetic applications.

Foundation stone Geospatial data provenance should be the foundation stone of all geographic information systems (GIS). Metadata carries a lot of information, but rarely the source, accuracy and currency of the geospatial data it is related to. I designed and ran the first professional Electronic Chart Display and Information System (ECDIS) course in Ireland in 2003. ECDIS and SP57 electronic charts and standards, which have evolved considerably since then, have ensured that the same data provenance remains an inherent part of chart information, now in electronic form. This facilitates confident integration with real-time location systems and with the navigator’s professional interaction to turn ECDIS information into real-time navigation intelligence for critical decision-making. It is true, though, that the intelligence determined from marine and air information systems may not always be perfect if provenance data is not specified correctly to survive the passage of time. A major finding of my dissertation for my Masters in 1997 was the misidentification of the horizontal datum published on most charts of Irish waters at the time as an “Ordnance Survey of Ireland Datum”, suggesting a relationship to the OSI and one of their published transformations, when in fact it was a British Admiralty datum based on a Second World War Office False Origin (WOFO) Spheroid – the correct interpretation of which had been lost in time and across national administrations. In this case, while provenance data had existed, it had been left open to misinterpretation due to the passage of time. For this reason, since my conversion to predominantly landlubber geospatial pursuits in 1998, the above axioms and the WOFO revelation have guided my approach. Too often I have been told that a GPS was producing co-ordinates that were “hundreds of kilometres in the wrong location”: the difference between Irish Grid and Irish Transverse Mercator (ITM) co-ordinates mistakenly plotted on mapping with the opposite co-ordinate reference system (CRS). Too often have I heard allegations of height/elevation errors of 56 metres or 2.5 metres, both of which are respectively the rough differences between two different ellipsoid heights and two different orthometric heights. And nowadays we have the differences between the OSGM 02 and the OSGNM 15 Geoid models to contend with also. These can be the cause of much argument in court when road sections don’t precisely meet as intended, when contracts are disputed or when two neighbours dispute the correct location of their common boundary. Unlike the marine/air navigation examples, they are not real time and not safety critical but the cost and disruption can be substantial. I recently provided geodetic technical input into a proposal to provide a Middle East national oil management company with the solution to decades of failure to maintain the provenance of its own key geospatial information. That failure was not only incurring substantial cost on an ongoing basis, but is now costing close to US$2 million to put the resulting issues right. “ INFORMATION IS NOT INTELLIGENCE UNTIL IT IS PROCESSED AND VALIDATED AGAINST OTHER INFORMATION AND OTHER SOURCES.

In maritime law, the geospatial definition of boundaries and related baselines is critical to national governance. For all these reasons, geospatial data exchanged without the full details of the source, accuracy, CRS and vertical references used is unforgivable in this technological age where doing this is easily facilitated.

Precision versus accuracy Nowadays, the widespread use of GPS/Global Navigation Satellite System (GNSS) as the source of geographic information means that there are other not-so-obvious issues that must also be identified and recorded as part of geospatial data provenance. This raises the spectre of precision versus accuracy. You can express a latitude and longitude derived from a mobile phone to as many decimal places as you wish, but that does not specify the position accuracy and, therefore, pretentious precision could belie the suitability of the data for any location intelligence that may be determined from it. Where high-accuracy GNSS survey systems are used to determine geolocation, then there are also other data provenance considerations because of modern practice. The move from hard nail ground-based primary geodetic control to control based on the ongoing network adjustment of the location of the phase centres of GNSS antennas dictates that any co-ordinates or elevations calculated must now also include provenance data. Failure to record this information frequently results in disagreements. Like is not compared with like and too much is expected of data that may be expressed with high precision or even given the term ‘precise’ but has an unsuitably low accuracy probability. The introduction of Eircodes in Ireland is one of the most significant geospatial infrastructure projects undertaken in recent years. It has introduced the idea of geospatial accuracy to the general public. Some issues reported, however, have raised questions about the provenance of the source data and related processes used to generate and deliver the code. There are many other issues to be considered when it comes to geospatial data provenance. It is definitely worthy of further research. From my perspective, much can be learned from marine and aeronautical practice, where geospatial data provenance is critical to safety. There is no doubt that geospatial data needs very specific data provenance information to support the determination of reliable and appropriate location intelligence from it.