The three-dimensional morphology characteristics of discontinuities have a significant impact on the anisotropy of rock mass. Quantitative representation of these characteristics is crucial for the study of rock mass mechanical behavior. The model utilizes four variables: the height (h), width (d), spacing (x), and extension length (z) of the protrusion. This paper presents a mathematical model for the quantitative representation of the three-dimensional morphology of discontinuities using visible light projection and image binarization. The mathematical model's application method is explained, and the proposed calculation concept for the 3D morphology software design for discontinuities offers a theoretical foundation for related investigations.