Ordnance Survey Blog

Wessex Archaeology – mapping the past

By Gemma, 14, July, 2010 10:50 am

You might have read my blog on Wessex Archaeology’s finds at our new head office, describing the Bronze Age Farm that was once on our Southampton site…while chatting with the team, based on the outskirts of Salisbury, I discovered just how much they rely on our data, both on paper and in numerous electronic formats. Talking to Paul Cripps, Geomatics Manager at Wessex Archaeology (WA), I discover that their mapping interests run from historic mapping to OS OpenData and a whole range in between.

Much of WA’s work is spatial, finding out how things relate to each other. From historic buildings to excavations to the marine environment, mapping is fundamental to everything WA do. But they don’t just use it as a backdrop, they add information about their excavations and finds too and attach that to their mapping. I was surprised to find that the historic mapping is not only needed to understand change through time but to ensure the accurate interpretation of aerial photography amongst other things; it is not always easy to work out what is shown in an aerial photograph alone and the feature may not be shown on more modern maps, a second world war bunker on a disused airfield can look very similar to a Roman fort from the air!

Paul explained to me how surveying techniques have changed over the years, “OS Net changed the way WA worked. We’ve gone from using measuring tapes to mark out the locations of digs, to using total stations (tied in to trig points) to using differential GPS units (which had to be set up 4-5 hours before work could start). SmartNet uses the mobile phone network and it only takes 5-10 minutes for us to start surveying and we capture 95% of all work with our Leica SmartNet devices. We still use total stations to survey areas where 3D recording is needed, such as buildings and structures, skeletons in graves and so on, but trenches and all basic features can be accurately captured using SmartNet.

“A lot of people wonder what we’re recording all the time, but initial digging on a site only covers a percentage of the area and you need to accurately map these locations. Basic info can be added onto the GPS unit as you work, then we process it in AutoCad or ArcGIS, attach our full database records to the surveyed features, add modern and historic mapping and have all the information we need in one spatial environment.”

WA have six SmartNet systems and want to invest in more as being able to do everything on site makes life much faster and efficient. Rather than a survey team driving around the country and setting surveys up, now the GPS systems are so simple that archaeologists can do the majority of work themselves after some basic training. This leaves WA’s survey specialists to work on training and standards (and still do some surveying too!).

There are some great examples of WA surveying on their website and loads more pictures of them in action on Flickr too.

Images produced by kind permission of Wessex Archaeology showing range of surveying techniques. More information can be found on Flickr.

Using GI and maps | historic, mapping, opendata, os net, wessex archaeology