Rock face diagnosis is a monitoring operation that is used to optimize rock-risk treatment works in terms
of ensuring that safety requirements are met at the lowest cost. Diagnoses require measuring the
location and orientation of rock discontinuities at the surface of the rock mass. These measurements are
then entered into a structural model that extrapolates the data collected at the surface to the inner part
of the rock mass. Currently, most surveys are empirical and are carried out manually using a compassclinometer.
In addition, they tend to examine only the most highly fractured area of a rock face, even
though safety considerations demand an exhaustive study of the whole face. These deficiencies can be
overcome by using dense 3D measurement techniques such as terrestrial laser scanning and optical
imaging to obtain a more complete 3D model and structural statement. Hence, we have developed a
semi-automatic process that allows 3D models to be combined with the results of field surveys in order
to provide more precise analyses of rock faces, for example, by classifying rock discontinuities into
subsets according to their orientation. Further research is being carried out in order to combine 3D data
and 2D digital images as a support for structural survey. Trials carried out in a limestone quarry in the
French Alps allowed us to compare data sets obtained using manual surveying methods, the well-known
laser scanning method and the lower-cost photogrammetric survey method.