Development of 3D/4D GIS - Geoscientific Information Systems

• Although conventional GIS are generally very effective tools for modelling 2D topographic data, they are unable at present to deal with the complexities of the 3D and 4D data found in the geosciences (both above and below the surface). The aim of this research is therefore to develop new techniques which can be used in mapping and modelling of multi-dimensional data-sets. This will aid improved interpretation - from the initial stages of correlation and interpolation of data to interactive visualisation and spatial analysis.

• Interpretation of phenomena in the earth sciences usually has to be made from a sparse and irregular collection of data samples in a complex 3D environment. Often there is more than one plausible interpretation, and, as a result, datasets need to be continually manipulated to test the various hypotheses. Procedures such as correlation / interpolation between samples and subsequent visualisation, can be very laborious and time-consuming processes manually, which has encouraged the use of computerised methods. However, the generally sparse nature of the sample data frequently results in a level of uncertainty that presents a severe challenge for deriving meaningful computer models.

• To handle this uncertainty involves incorporating "hard" (quantitative) data together with pre-existing knowledge to reduce the number of possible interpretations and ambiguity of models. Once the model data has been collated we can then transfer it to a system allowing interactive data visualisation and exploration (in our case: AVS/Express). This may involve conventional views (carpet plots, fence-diagrams, slices etc.) or the use of more advanced 3D volume visualisation techniques (eg. isosurfaces, ray-tracing) which can be used to explore the interior of models.

• 3D/4D models have been developed from a variety of data-types including borehole records, geophysical data, palaeontological samples, meteorological phenomona, pollution plumes and topographic data (see Images) Software being used in this project includes AVS/Express (state-of-the-art 3-D visualisation system) ARC/INFO (for GIS) and CLIPS (an expert system shell).

• We are also developing the use of virtual reality for modelling in the geosciences by converting the geometry models created by AVS/Express into VRML. The resulting script can then be read into a VR browser and full 3D interaction with the model is then enabled for all users across the Internet without the need for specialised software. Furthermore, by combining VRML with Java (or JavaScript) we can link object behaviour with its 3D representation in the browser enabling both query and visualisation of complex spatial data from a basic desktop machine. More details are available on The Virtual Environments & VRML Page.

EMAIL: IBrown@glam.ac.uk

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