Surveyors Fly High

15 December 2007

Surveyors can now fly between geodetic marks at the click of a button thanks to a new application for viewing information on LINZ's geodetic database.

Unless you've tripped over one of the steel pins set in the pavement near your home, you probably won't know where the closest geodetic marks are. But for surveyors, finding nearby geodetic marks from the more than 100,000 around the country is an important part of their job.

Bird's eye view

In the last year surveyors have used the geodetic database on LINZ's website more than 460,000 times to find detailed information about individual marks, which are the basis for accurate maps, charts, boundary surveys and a variety of engineering and construction projects throughout the country. But using the database to find sets of local marks hasn't always been easy, says Jeremy Palmer, Data Analyst (Geodetic).

"Previously a spatial search for marks was reasonably cumbersome, making it difficult for surveyors to locate sets of marks. A spatial interface (like an online map) for users has been on our wish list for a while."

Now LINZ has come up with a clever solution. Surveyors can now connect to the database through three dimensional geographic applications like Google Earth. The marks appear on Google Earth's satellite imagery, allowing surveyors to browse a local area for marks. By clicking on the marks, surveyors can then find detailed information.

A new feed

The connection occurs thanks to a data feed from the LINZ website in the Keyhole Mark-up Language (KML) format. This format is an XML-based language for describing three-dimensional geospatial information, and is similar in nature to LandXML (a format used by New Zealand surveyors to exchange cadastral data with Landonline).

The data feed is synchronised with the geodetic database so maintenance and updates to the database are reflected in applications like Google Earth. The feed was developed entirely in-house, and the response has been very encouraging.

Jeremy demonstrated the new application to congress delegates at the recent South-East Asian Congress in Christchurch.

"There was a lot of interest and the feedback was very positive," says Jeremy.

The data-feed requires a desktop application compatible with KML feeds. Google Earth is freely available for download and has been enormously popular with the public.

New google maps application released

In a related development, LINZ has released a major enhancement to the current geodetic database web application which will enable surveyors to search for geodetic marks right down to street-level using Google Maps technology. No additional software is required as the map view is embedded directly into the LINZ website - see the geodetic database.

"Google Maps doesn't have the three-dimensional view or the same amount of satellite imagery of Google Earth," Jeremy says, " but in some ways it's easier to use and it also contains useful topographic and street information."