Abstract: A method for identifying timber surface properties using linearly polarized electromagnetic radiation containing various different wavelength components. Of the scattered radiation are measured by wavelength ranges the intensity components I.sub.min and I.sub.max that are mutually perpendicular as regards their polarization plane, wherein the polarization plane of the component I.sub.max is the same as that of the radiation directed to the surface. The identification of the surface types is made on the basis of the information about the color tone of the surface and the fiber structure achieved from the variables I.sub.min and P=(I.sub.max -I.sub.min)/(I.sub.max +I.sub.min).