If you have a geological unit elevation and you want to calculate/measure the strike and dip at a certain point, this tutorial might help you. The ThreePointMethod is a QGIS plugin that calculates a plane strike and dip direction using the threepoint method. It works with a point shapefile and a digital elevation model. The tutorial covers the whole procedure to calculate strike/dip from an ideal raster and a geological unit bottom elevation.

Input data
You can download the input data from this link:
https://hatarilabs.com/ihen/howtom...