About laser scanning
About the Project Home Trent & Peak  Archaeology Nottingham’s  Caves What about  my cave? Project Team About  laser scanning
About laser scanning The caves surveys will use a 3D laser scanner to record both the overall  shape and surface details. The individual surveys are then tied in to an overall map by GPS.  
Nottingham Caves Survey
Trent & Peak Archaeology / The University of Nottingham
The laser scanner Laser scanners come in a variety of forms but they all work in a similar way. The scanner fires out a beam of laser light which reflects back from the first thing it hits. The instrument measures the amount of time it takes for the light to return, and from this can calulate how far away that object is. The scanner then rotates the beam a little, and takes another measurement. It continues to rotate vertically and horizontally until it has taken measurements in a 360-degree horizontal circle and usually a 310- degree vertical circle. All the measurements are accurate to around +/- 2mm. From these measurements we have an almost complete 3D survey of a cave. What makes this technology really exciting is the speed at which modern laser scanners work - up to 500,000 survey points per second! The resulting ‘cloud of points’ can be connected to adjoining scans to produce complete surveys of cave systems. Once downloaded into the processing software we can do lots of different things with the point cloud data - make simple sections and plans, elevation maps and isometric images, fly-through videos, explorable .mov images, TruView web delivery, and virtual or real models. Because of the accuracy of the survey data, it can also be used for monitoring the caves. We can go back and re-survey a cave after a year or a hundred years and see exactly how and where it has changed.
You can read more about how the project will survey caves on the methodology page, and the best place to see examples of surveyed caves are on the individual cave pages, like the High Pavement caves, here. The image on the right shows a point cloud from two individual scans, coloured by intensity data. This image is single-sided - the walls nearest you are hidden.
Using the scanner
About  laser scanning