Phase Gray Code 3D Imaging Method

In recent years,the human demand for acquiring three-dimensional information about objects has increased steeply,prompting the booming development of threedimensional imaging technology.With the advantages of high resolution,wide field imaging and high efficiency,coded structured light technology has become a research hotspot for optical non-contact 3D imaging,which is widely used in industrial manufacturing,reverse engineering,product inspection and other fields.The coding structure light can be divided into digital code coding and analog code coding,digital code has higher anti-interference ability compared with analog code,in which,digital code with binary code and Gray code as the main coding method.Compared with binary codes,only one bit changes between adjacent code words in Gray Code,which is more resistant to interference.Gray Code technology can measure surfaces with highly dramatic changes or discontinuities,thus becoming one of the most practical optical 3D imaging methods.However,the traditional Gray code sampling intensity for coding and decoding,in the actual measurement due to the system itself hardware noise,the interference of the measurement environment and the geometric characteristics of the object surface,etc.will inevitably lead to distortion of the coded image,and then produce decoding errors.Moreover,the decoding error increases with the increase of interference,so that the threedimensional measurement of coarse error,resulting in unusable measurement results,measurement loss of meaning.In order to improve the anti-interference ability of coded images,this paper proposes a phase Gray code coding method,in which phase is used for coding and decoding to improve the anti-interference ability,and a phase Gray code coding and decoding model is established through theoretical analysis to form a phase Gray code3 D measurement method with high anti-interference ability.Firstly,we study the 3D imaging methods of binary code and Gray code,which are the most widely used in digital codes,analyze the coding and decoding principles of the two digital codes,establish a 3D imaging model based on optical triangulation,use 3Dmax simulation software,build a simulation 3D imaging system,and use the system to conduct simulation imaging experiments for binary code and Gray code3 D imaging methods.Then,we propose a phase Gray code 3D imaging method with high anti-interference capability,specify its coding and decoding principles,and conduct simulation and comparison experiments for binary code,Gray code and the proposed phase Gray code method using the 3D simulation system built respectively.Finally,a structured light 3D imaging experimental system is built to establish a mathematical model expressing the relationship between the decoded value of the encoded image and the spatial 3D coordinates of the measured surface.Using the system based on binary codes,Gray codes and the proposed phase Gray code method,actual 3D imaging experiments are conducted for plaster boards and plaster balls with typical surfaces and for vases,masks,human hands and metal castings with complex surfaces,respectively.