Recent studies concerning bryophyte canopy structure applied various modern, computer analysis methods for determining moss layer characteristics drawing on the outcomes of a previous research on surface of soil. Surface roughness index Lr was hereby used as a monitor of quality (and condition) of bryophyte canopy. We explored stereo photogrammetry, a non-contact passive method of collecting distance information about surfaces, as a method to acquire 3D model of bryophyte layer and thus $L_{r}$ and compared it with methods already performed by other authors - contact probe, LED scanning and 3D laser scanning. In contrast to active methods, this method relies on detecting reflected ambient light, therefore, it does not emit any kind of radiation, which can lead to interference with moss photosynthetic pigments, nor does it affect the structure of its layer. This makes it much more suitable for usage in natural environment.