Rockfalls are common in the countries with significant amount of mountain area. It is estimated that 27 percent of the world’s land surface are mountains and about 12 percent of the world’s population lives in the mountains. Due to that fact, there is a need of constructing new roads and railways along mountain slopes. In those areas, rockfalls can cause serious damage to infrastructure with possible human losses. Ensuring rockfall stability is a major safety goal along railways and highways. In order to simplify the complicated equations involved in rockfall modeling, computer simulation programs have been developed, both in twodimensional and three-dimensional domains. The analysis of rockfalls includes estimation of trajectories of the boulders that falls from specific height along the slope. Once movement of the rock has been initiated, its falling behaviour is controlled by slope geometry, slope properties and boulder properties. The geometry of the slope represents one of the most important parameters and therefore it has to be accurately measured and determined as an input parameter for calculations of rockfall stability. Two-dimensional simulations require slope profile divided into several segments along slope, while the three-dimensional simulations require dense and accurate data in the form of digital terrain model. In this paper available methods for determining the geometry of slope are presented. Advantages and disadvantages of each method are discussed taking into account how it affects the final result of rockfall analysis.

rockfall stability; photogrammetry; laser scanning; total station