Geoid Models or Tripods: Which is More Important? - 06/07/2016


What skills should we be teaching young surveyors? Why is addressing so important? Should we really disturb the beast that is the Land Registry? And how can we raise the levels of global tenure? In this issue GW tries to provide some answers to these challenging questions.

Gordon Johnston in his Chair’s column (page 09) poses an interesting question. Will young surveyors always need to know how to level a tripod? He raises this somewhat startling question in the context of the RICS review of core competencies for the APC, the test of professional competence for chartered surveyors. Perhaps students don’t need to know that but surely they should get the education to realise that, if one far off day the batteries having all failed and someone reaches for an ancient T2 and tripod in the back of the store to send them off to survey, it needs a level platform to take readings from. Just as they should be aware of the limitations of optical instruments.

The future is one of many paths but at the root of most surveying is geodesy. It is probably more important for a newly graduated surveyor to understand the significance of transformations and geoid models and how they might affect a client’s navigation or positioning system, than the procedure for levelling a tripod. Equally important is an ability to explain geodetical transformations in relatively simple language to a client. OSTN and OSGM are the transformations that link 3D positions measured using GNSS with the national coordinate and height reference systems of Great Britain, Ireland and Northern Ireland. There are new transformations available for each territory. Surveyors should note the average change of levels of 25mm in mainland Britain, as this may have implications for anyone trying to merge legacy data with new data. Turn to page 18 for more.

Addressing champion

Although arcane cartographic transformations are rarely the cause of problems in addressing, the reality that an address is more than just a postcode has still to dawn on many. The sterling work of Ordnance Survey and Geoplace in keeping emergency service providers, local authorities and others up to date with UPRNs often goes unrecognised. It was good to hear at the annual Geoplace conference that government minister Matthew Hancock not only understood the significance of getting addressing right, but declared himself a champion of the local government custodians who toil away on this rather boring but necessary work, which often yields occupants who have avoided commercial rates or council tax for years.

The Unique Property Reference Numbers total over 40 million (10 million more than Royal Mail postcodes). They enable emergency responders to reach their callout destination quickly, always provided their dispatchers have kept their databases up to date. Without regular updating someone may die because they have to wait too long for a paramedic or ambulance that can’t find the given address, which is exactly what may have happened recently in London.

Addressing global insecurity of tenure

We stay with land and Dr Robin McLaren’s magisterial review of global insecurity of tenure. Based on shaky statistics it seems that only around 30% of the world has some form of secure or registered title. To register more landholder’s rights McLaren argues that there are a growing range of new and cheap tools available to help people. Mobile phones and the Internet offer a potentially lifechanging way of recording land rights and claims. But in some parts of the world we need to better understand how indigenous people regard both land use and ownership. We have much to learn. This article is abridged from a longer paper and is essential reading for all involved in international land management.

Lastly, we have reports from two attendees at the recent FIG Working Week in Christchurch New Zealand. In the next issue I hope to bring you a more detailed review of the papers presented. Enjoy the summer, we shall return in September.

By Stephen Booth, Editor of Geomatics World

This article was published in Geomatics World July/August 2016

Last updated: 24/05/2017