3D Shape Measurement of Diffused/specular Surface by Combining Fringe Projection and Direct Phase Measuring Deflectometry

The three-dimensional (3D) data of object surfaces, like a precision machine part, play an important role in the fields of aerospace, automotive industry, augmented reality, heritage preservation, smart city, etc. The existing fringe projection profilometry and deflectometry can only measure the 3D shape of diffused and specular surfaces, respectively. However, there are many components having both diffused and specular surfaces. This paper presents a novel method for measuring the 3D shape of diffused/specular surfaces by combining fringe projection profilometry and direct phase measuring deflectometry. The principle and calibration method of the proposed method are elaborated. Experimental studies are conducted with an artificial diffused/specular step having diffused/specular surfaces to verify the measurement accuracy. The results on several objects show that the proposed method can measure diffused/specular surfaces effectively with certain accuracy. Error sources are also analyzed to improve the measurement accuracy.