The term clear wood corresponds with the macroscopic scale, where the orthotropic elastic model is commonly used. This model is defined by a compliance matrix composed of nine parameters. The current experimental standard methods for obtaining these parameters are time consuming, as different specimen configurations and a careful preparation for a specific grain orientation are needed. The optical digital measurements (ODM) are improving those traditional procedures. For the specific case of clear wood, they have the additional advantage of properly link the experimental data with the assumed theoretical macro scale model. This work presents a new method for determining the compliance matrix of clear wood using just one rectangular prism as a specimen with an orientation of the grain that does not coincide with the axes defined by its edges. The specimen is loaded in the three mutually perpendicular directions defined by the prism, and their corresponding elongations and angular distortions are measured simultaneously by using 3D ODM, ARAMIS® (5 Mpixels). The method was initially validated on ash. Reasonable results, according the used resolution, were obtained; even though a higher resolution is needed for getting a proper accuracy.