Problems of active coherent triangulation sensor applicability to non-stationary reflective 3D surface sensing are considered. As is shown in the paper, the accuracy of a sensor is connected not only with the resolution along the range and field of view, but also with the triangulation angle and direction of the normal to the surface, and with defocusing and aperture limitations of the optical system. Moreover, the processing algorithms of light distributions and statistical analysis of measured data are very important. The conditions for undistorted surface reproduction are defined. In the case of violation of such conditions only statistical evaluations of basic surface parameters are possible.