Three-dimensional Integration and Visualization of Structural Field Data: Tools for Regional Subsurface Mapping Integration Et Visualisation 3-d De Données Structurales De Terrain: Outils Pour La Cartographie Géologique Régionale

Three-dimensional computer modelling of geological phenomena is rapidly emerging as a field within the already mushrooming science of computer visualization. In geological applications three-dimensional interpretations are routinely performed through the use of two-dimensional map data and knowledge about the geological history of an area. These interpretations are traditionally depicted with isometric or perspective block diagrams and vertical or horizontal cross-sections. Constructing these three-dimensional snap-shots has been laborious, imprecise and limited to a single viewpoint. The methods presented here automate some of the more laborious tasks and enhance the threedimensional interpretation environment. Methodology focuses on using field-based structural data, from a variety of scales, to create speculative three-dimensional surfaces that can be useful in addressing geological problems. These methods could help in resolving cryptic early fold geometry, extending stratiform mineralization and the subsurface interpretation of regional thrusts, unconformities or key lithostratigraphic boundaries. Several UNIX based programs are presented for performing the interpolation, extension and conversion tasks required in these approaches. Programs are implemented in conjunction with the commercial three-dimensional visualization and modelling software EarthVision® and gOcad®. Algorithms focus on the densification and variable projection of distributed three-dimensional data which share a common curvilinear geological feature. The result of the various interpolation and extension functions is the conversion of twodimensional lines to three-dimensional surfaces. A polynomial and hybrid B-Spline interpolation technique optimizes geometric property components. The automated data-driven technique is applicable for geological problems in which structures are constrained by local linear and planar measurements. Input features are topographic intersections of relatively continuous irregular curved surfaces, which have a near linear known depth predictability at some point along the structure. The local direction cosine estimates derived along surface traces of geological structures are interpolated, and direction vectors linearly projected to depth to form local