3D Laser Scanning Services provided by Birmingham Archaeology/HP Vista

3D Laser Scanning Services:

Birmingham Archaeology in Association with

The IBM Visual and Spatial Technology Centre

New developments in survey technologies are changing the ways in which archaeologists are approaching heritage. Laser scanning using the IBM VISTA's Leica HDS 3000 is providing new ways to think about recording and interpretation.

Traditionally, the archaeological survey of a building requires the use of a Total Station to record subjectively chosen three-dimensional positions. A ‘join the dots’ process in CAD is then used to generate elevations. The survey is undertaken in the field to generate a particular product which is derived from it.

With laser scanning this has fundamentally changed. The machinery records three-dimensional positions at a predetermined resolution over a chosen area, generating thousands of high-accuracy coordinates. The surface of a scanned structure is therefore represented as a ‘point cloud’ which three-dimensionally represents its form. This point cloud will also include areas of a structure that might otherwise be inaccessible due to height or Health and safety.

There are two principal advantages of using laser scanning for recording heritage. Firstly, the technology is extremely rapid, vastly reducing the time required on site, which is commonly an important priority. Secondly, it generates vast quantities of data which means that the archaeologist is not restricted to the skeleton measurements traditionally taken. Once back in the office it is possible to take numerous measurements and to interrogate the data, as well as generate elevation drawings if required. Since one of the key purposes of archaeological survey is to record threatened structures for future generations, the resulting datasets provide an extremely valuable archive. Future investigators will be able to access the whole ‘virtual’ structure rather than relying on just the subjective drawings.

In addition to recording thousands of three-dimensional positions, the laser scanner also records two additional parameters. Colour is recorded using the in-built digital camera and this can be mapped to each data point collected, providing a colour-rendered cloud of three-dimensional data. In addition to colour, the scanner records reflectance intensity. Different surfaces will reflect the laser beam better than others, and this information may be mapped using different colours onto the point cloud data. This intensity data is able to highlight differences between different material such as brick, stone or mortar, and can even identify different phases of repair, perhaps through different types of plaster or render.

The quantities of data generated from laser scanning can also be used in a variety of ways. In addition to providing a basis for generating drawn elevations and plans, the data can also be modelled to generate continuous mesh or solid surfaces that can be exported to a variety of architectural software packages. These models can form the basis for reconstruction and visualisation perhaps presented within virtual reality software. Equally they can be used as the basis for architectural design, to explore how new buildings might fit with the current environment.

Laser scanning is changing the ways in which heritage is recorded and understood. It is changing the speed of survey and the quality of the resulting data. It is also providing new archiving opportunities whereby threatened structures really can be recorded virtually for future generations.

An Adobe pdf file detailing our 3D Services can be downloaded by right-clicking here