July 11, 2013
3D Map Of Richard III’s Grave Created Using LiDAR
Lawrence LeBlond for redOrbit.com - Your Universe Online
Excavators are currently on a month-long dig at the site of the former Grey Friars church at a car park in Leicester, looking to uncover medieval artifacts and possibly the graves of three beheaded friars from the early 1400s. Meanwhile, one University of Leicester researcher is busy creating 3D models of the grave site of Richard III, who was hastily buried in an unmarked grave in 1485 and discovered last September.
David Ackerley, a postgraduate researcher at Leicester's School of Geography, has used a terrestrial laser scanner to map the exact shape of Richard III's grave, creating a highly-detailed 3D model. The laser scanning was combined with digital photogrammetric techniques to produce an interactive model, showing off surface details in an array of colors that mark height details.
The remarkably accurate reconstruction will serve as a useful tool for studying the grave in its current condition during future assessments. The reconstruction will also be made available to the public and will be on display at the proposed Richard III Visitor Centre to be constructed near the dig site.
The laser scanner used for the reconstruction is part of the Leicester LiDAR Research Unit, based in the Department of Geography, directed by Dr. Nick Tate. Ackerley placed the LiDAR (Light Detection and Ranging) instrument at various points around the grave to get a detailed picture of the area.
The scanner fires out laser pulses in a 360-degree arc, recording the time it takes for the beam to bounce off a surface area and return to the instrument. The information gathered at each position was combined to build up a 20-million-point-cloud of the grave and reveals everything down to the precise soil textures of the grave walls. The data from the laser-scanning will then be converted into a triangulated irregular network (TIN) surface and combined with a survey made using digital photographs.
The digital images of the grave were taken by Jose Manuel Valderrama Zafra, a visiting academic from University of Jaen, Spain. Zafra was invited to join the project by fellow archaeologist Dr. Mark Gillings of Leicester's School of Archaeology and Ancient History.
Zafra took more than 80 pictures of the grave from numerous angles and used 3D modeling software to combine the photos into a 3D model of Richard III's grave. By combining Zafra's data with Ackerley's LiDAR scans, a unique context and extra depth measurements of the surface can be attained, making it easier to see colors, features, shapes and dimensions of the grave.
"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," said Ackerley. "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 minimizing any disturbance caused. This really is the 21st century approach to the sketchpad," he explained.
"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," noted Zafra. "We also need to correct the different deformation parameters of the camera in order to minimize 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," he added.
Richard Buckley, lead archaeologist at the Grey Friars dig site, 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."
The grave of Richard III was discovered in September 2012 by Philippa Langley of the Richard III Society. Langley, who originated the search for Richard III, discovered the possible site of the humpbacked King's burial ground underneath a car park in Leicester. After digging commenced in a small area under the car park, human remains were discovered that were believed to be those of King Richard III himself.
After months of analysis, DNA testing ultimately confirmed that the bones did in fact belong to Richard III.
Image Below: Scans of Richard IIIs grave using LiDAR (laser) scanning. The colors simply relate to height (i.e. red is surface height; blue is the lowest level of the excavation). Credit: University of Leicester/David Ackerley