ACCURACY TESTING OF 3-DIMENSIONAL DIGITIZING SYSTEMS

An accuracy test designed as a standard for digital occlusal wear measurement devices was applied to such a device designed by the authors. The test was used for quantitative determination of measurement error for a given angle of tangential contact with the inclined planes of the surface being measured. Using known dimensions of the digitizer contact tip and of a precision steel sphere, we determined trigonometrically the error in the Z-axis measurement due to the slope of any point on the surface of the sphere. These values were used for a point-by-point correction of data obtained from actual digitization of the sphere. The corrected values would equal zero if no mechanical source of error existed. These values, then, quantitatively indicated the accuracy (in microns) of the device as a function of the slope of the measurement point. The results indicated a linear relationship between surface slope angle and measurement error for the device tested.