Interpretive tools for 3-D structural geological modeling Part I: Bézier-based curves, ribbons and grip frames

Interpreting the geometry of geological objects is a standard activity of field-based geologists. We present new graphics tools that will aid in extending this activity from 2-D geological mapping into a 3-D environment. Much of the existing 3-D geological modeling software supports the construction of objects with the input of dense control data. However, for regional mapping and near mine exploration work, sparse data is the norm. Tools are required therefore, which give the expert interpreter full control of the graphics objects, while at the same time constraining interpretations to specific control data from field observations. We present the initial results of a software design and programming project for the visualization of complex regional scale geologic objects using Bezier-based graphics tools that are optimized for sparse data interpretation. We also introduce the concept of a structural ribbon, which is a 3-D extended map trace, along with methods for the optimization of surface construction using graphical grip frames.