A new algorithm for detecting discontinuity areas from photogrammetric 3D models is presented. The algorithm has been tested under laboratory conditions as well as with real world data. A comparison with values from compass readings showed average deviations around 1° in both cases. The automatic detection of discontinuities drastically shortens field time while simultaneously increases the number of measurements per discontinuity set. An extension of the algorithm for regarding linear structures based on photo analysis is foreseen leading to a first complete automatic discontinuity detection.