David Ackerley, a postgraduate researcher in the University’s School of Geography using the terrestrial laser scanner. Credit: University of Leicester
Researchers are combining laser scanning with digital photogrammetric techniques to produce an interactive map of the grave discovered at the Grey Friars church by Leicester archaeologists in September.
The remarkably accurate reconstruction will preserve the grave as it was following the excavation of Richard’s skeleton – and will be a useful tool for studying the grave’s conditions in future.
The researchers also hope the reconstruction will be made available to the general public in the proposed Richard III Visitor Centre.
David Ackerley, a postgraduate researcher in the University’s School of Geography, used a terrestrial laser scanner to map the exact shape of the grave. This instrument is part of the Leicester LiDAR Research Unit, based in the Department of Geography and directed by Dr Nick Tate.
The instrument was placed at various points around the grave. Using the principles of LiDAR (Light Detection and Ranging), it fires out laser pulses in a 360 degree arc, recording the length of time taken to bounce off a surface and return to the scanner.
The information gathered at each of the measuring positions was combined to build up a 20-million point-cloud of the site – revealing everything down to the precise soil textures of the excavated grave walls.
David uses this technique as part of his geomorphology research to monitor how the surfaces of gravel-bed rivers structure over flood events and how this influences particle entrainment and sediment transport. It allows him to survey the fluvial environment without, importantly, disturbing his area of interest.
The data from David’s laser-scanning of the grave will then be converted into a triangulated irregular network (TIN) surface and combined with a survey made using digital photographs.
José Manuel Valderrama Zafra, a visiting academic at the University of Leicester’s School of Archaeology and Ancient History who was invited to join the project by fellow archaeologist at the University, Dr. Mark Gillings, used a digital camera to take more than 80 pictures of the grave from many different angles.
José, who is also an engineering researcher at the University of Jaén, Spain, used 3D modelling software to combine the photos into a 3D model of the grave.
The researchers hope to combine the two datasets by mapping the photographic model onto the surface derived from the laser-scans.
This would add context and extra depth to the surface – making it easier to see colours and features as well as the exact shape and dimensions of the grave.
David Ackerley said: “Laser scanning is a very useful surveying tool – especially as the technique is non-intrusive. Historically, you would have had to physically go into your survey area and measure every point by hand.
“This technique allows for a quick, high resolution recording of features in areas that may be inaccessible – or where you want to preserve the layout of your site.
“In an archaeological context, the value of this non-invasive approach is that you can document the grave of King Richard III and generate a highly accurate and detailed virtual representation whilst minimising any disturbance caused. This really is the 21st century approach to the sketchpad.”
José Manuel Valderrama Zafra said: “The close range photogrammetry method we have used is able to obtain the 3D position of different points by the measuring the spatial intersection of the rays that define the same point in different photos.
“We also need to correct the different deformation parameters of the camera in order to minimise the final errors in the spatial definition of the points.
“This technique it is very interesting, because of its simplicity and the low cost of the materials needed to do it – it is even possible to do it with a simple compact camera.”
Archaeologists from the University of Leicester Archaeological Services have begun a month-long excavation of the choir area of the church – where Richard’s body was discovered in September.
Richard Buckley, lead archaeologist on the Search for Richard III, said: “What is remarkable about this is that we can create a truly objective 3D record of Richard III’s grave using modern technology. It can then be used by Leicester City Council for the Richard III Visitor Centre.
“It is a way of applying cutting edge techniques to an archaeological site. We hope to work from this and develop it further – and hope to use it during the current dig.”