On the visualization of 3D geological models and their uncertainty

3D geological modelling is increasingly becoming a standard tool among geological survey organizations. The corresponding 3D models are made ever more widely available to general users, ranging from the interested public to politicians and decision makers who might be economists or lawyers, most of whom have received no specific professional training in how to interpret these models. In order to allow these users to interpret this information meaningfully, clear and intuitive 3D visualization plays an important role. Further, the visualization should make the users aware of the uncertainty that is inherent in these 3D geological models, due to, e.g., scarce data and interpretation ambiguities. Currently, models are most commonly visualised as vector graphics, for example by using triangulated surfaces, which allows users to zoom in very closely without changing the quality of the representation. Thus, such visualizations give the impression that the geological structures in the subsurface are known with a precision of up to a centimetre. We will discuss different visualization options for certain geological models which are part of the standard geological modelling packages, such as Gocad or Petrel, outline the problems we see with the different visualizations, and show how the visualization could be improved and be made more intuitive using volume rendering. We will then provide a short review of which visualization methods are available in order to express the uncertainty in data and models, mostly from other scientific disciplines, and show how our suggested volume visualization could be augmented with the information on the uncertainty in the geological model. Using example data sets that we have generated and preprocessed using Skua-Gocad, we will explain the workflow and discuss the different options and problems to generate such visualizations.