This activity introduces stereographic projection in a manner different from my own undergraduate experience in structural geology. I learned to plot planes as great circles and lines as points on tracing paper. The tracing paper method provides students with some understanding of three-dimensional structural data and relationships among them (calculating an angle between planes, rotating data, etc.), but the theory behind why a plane is plotted in a particular way is obscured. I decided to teach my students about stereographic projection through linear algebra. Because linear algebra is a foreign concept to many introductory structure students, I introduce the concepts alongside the excellent three-dimensional visualization capability of OSXStereonet.

I introduce stereonets by working through the material in "SphericalCoordsBackground.doc", then walk students through a few exercises to get them accustomed to the OSXStereonet and Matlab interfaces: plot a plane in OSXStereonet, visualize it in three-dimensions, plot and visualize its pole; calculate the Cartesian coordinates of the same pole using Matlab and compare those coordinates with the three-dimensional view of the vector. I then introduce some operations in OSXStereonet, including calculating the angle between two lines, and picking a great circle that contains two lines, and have students first think through the mathematics of those operations, then complete the calculations in Matlab.