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g2gp 17-01-2009
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Creating and Using Virtual Reality: a Guide for the Arts and Humanities #

Virtual Reality Case Study Library#

Case Study 5: Virtual Wroxeter: Roman fortress#

Sally Exon, University of Birmingham

Virtual Wroxeter is a virtual reality model of Wroxeter Roman fortress in Shropshire. The model may be viewed on-line from http://www.bufau.bham.ac.uk/research/bt/default.htm or at the site museum at Wroxeter or Rowley's House Museum in Shrewsbury. It is also made available to schools on CD.

Wroxeter Virtual Fortress is a fully interactive educational package. Within the software, text is presented at a choice of three levels: UK national curriculum key stage 2 (age 9–11), key stage 3 (age 11–14) and an in-depth adult version. Background themes are introduced, including the Roman invasion of Britain, as well as topics interpreting the buildings of the fortress and life within the Roman army. The user explores the fortress using the computer mouse, moving around the reconstruction, 'walking' down streets, entering buildings or 'flying' over the fortress. Clicking on buildings displays text about them. There is also a guided tour option where the user is moved from building to building with text displayed at each part of the tour.

The Virtual Fortress was developed at the University of Birmingham Field Archaeology Unit (BUFAU) as part of a British Telecom sponsored project, Access to Archaeology. The project uses computer-based techniques to present data collected by the Wroxeter Hinterland Project to a wider audience.

The reconstruction was created using Superscape's VRT software. Due to the size and complexity of the fortress plan, and to avoid splitting the reconstruction into several worlds, a variety of optimisation techniques was used to minimise the number of facets displayed at any one time. The reconstruction was to be web-deliverable so filesize was an important consideration.

Techniques employed in this way were:

  • The inside and outside of buildings were built separately, the insides only being displayed as the user opens a door or enters a building
  • The hospital was a very large building with many similar small wards off a central corridor. A small number of generic rooms were created. One of these is positioned in the correct place when the user opens a door to enter a ward. This helped to reduce filesize by removing the necessity for copies of rooms to exist behind each door
  • The Software Development Kit was used to create an extension to VRT for performing Level of Detail (LOD) operations. VRT's own function (called distancing) calculates the distance of the viewpoint to the centre point of the object. This method is problematic if objects are very large or asymmetrical (such as fortress defences). In this situation the viewpoint may be close to an edge of an object but the distancing function calculates that the centre point is far away and swaps to a simpler version of the object. Splitting objects up into many smaller parts and distancing on each would have increased the number of facets displayed and the file size to an unacceptable degree. The extension that was developed calculates the position of the viewpoint from the bounding box of the object allowing large asymmetric objects to be used in the world.

The fortress and pages decribing it are highly integrated. Interaction between the VR and HTML was implemented using Javascript, DHTML and stylesheet techniques.

The use of low-resolution PC-based virtual reality techniques allows this software to run without the need for expensive specialist hardware or software.