Wednesday, February 23, 2011

Ancient buildings brought to life from historic maps

SOFTWARE that recognises the outlines of buildings shown on historic maps should make it easier to create digital reconstructions of long-lost cities. It could also lead to virtual museum exhibits of historic locations.

The conventional method for digitising paper maps involves the labour-intensive process of tracing over buildings by hand. Now a team led by Stephen Laycock of the University of East Anglia in Norwich, UK, has developed software to do this.

On maps where buildings are shown in characteristic colours, the software is fully automatic. It first detects blocks of colour on a scan of the map, and then highlights the edge of each block to generate a clear outline of the building. It will also work with black and white maps if the user clicks a point inside each building.

The automatic mode is between 10 and 100 times faster than tracing the outlines by hand. Even with black and white maps, it is at least twice as fast.

One problem when working with old maps is that the scale can be seriously distorted. The software can correct for this by overlaying the building outlines on an accurately surveyed modern map.

"I can certainly see myself using it," says Paul Richens of the architecture department at the University of Bath, UK, whose team now does a similar job by hand. "We take the old maps and stretch them a bit - a pretty laborious technique," he says.

The extracted outlines can be imported into a commercial software package called CityEngine that generates 3D images with the help of information about what buildings from the period in question would have looked like. Laycock suggests that museum curators might use the software to add interactive tours of historic locations to their exhibits.

New Scientist. 2011. "Ancient buildings brought to life from historic maps". New Scientist. Posted: February 9, 2011. Available online:

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