Study On The Optimization Of Color Three-Dimensional Topography Measurement Based On Fringe Structure Light

The structured light projection method in the optical three-dimensional measurement method has high measurement accuracy,high speed,low cost,and non-contact with the measured object,and is widely used in biometric recognition,reverse engineering,medical industry,workpiece detection,cultural relic protection,scene scanning,etc.With the development of high-precision projectors and CCD(Charge Coupled Device)cameras,color composite sinusoidal fringe projection technology has also been widely studied and applied.However,due to the influence of the measurement system software and hardware and the external environment,there are crosstalk,chromatic aberration and system nonlinear response errors between the color channels in the three-dimensional imaging system.These kinds of error sources will seriously reduce the accuracy of the phase measurement and affect the three-dimensional shape recovery result of the measured object.In this thesis,several possible error sources in the color composite fringe projection3 D measurement system are analyzed theoretically.For a known measurement system,the coupling effect between the color channels of the camera and the projector is fixed,so crosstalk between channels can be compensated for using the calculated crosstalk coefficients.The magnification chromatic aberration between color channels changes the overall magnification and number of stripes of the fringe pattern.For this error,this paper specifies the phase difference between the red green and blue channels based on the blue channel.After calculating the stripe difference by the phase difference between the channels,the correction projector projects the number of stripes of the three color channels to compensate for the error.Finally,the system nonlinear error caused by the nonlinear response of the camera and projector to the light intensity is compensated by establishing a compensation table.The feasibility of the proposed error compensation method is verified by experiments.Based on the proposed error compensation theory,a hardware experiment system is established.First measure the steps and plates for system accuracy evaluation.The absolute absolute error of the step is 0.141 mm before the error compensation,and the maximum absolute error after compensation is 0.070 mm.Before and after compensation,the root mean square error(RMSE)of the plate measurement results are 0.089 rad and 0.015 rad,respectively,and the error after compensation is reduced to 1/5.Then the white gummy plaster and palm were measured,and the color appearance of the palm was restored.After optimizing the system using the error compensation method proposed in this paper,the bear and the palm got better measurement results.The experimental results verify the effectiveness of the error compensation method,and prove that the proposed system optimization method can effectively reduce the error of color three-dimensional shape measurement,and improve the measurement accuracy under the premise of ensuring the measurement speed.