Research On 3d Shape Construction Technology Based On Focus Optimization

Three-dimensional shape construction technology is an essential research content of target space size measurement and calibration.It is widely used in the fields of industrial inspection,three-dimensional visualization,aerial remote sensing,and medical research.Shape from focus(SFF)is one of the typical three-dimensional topography construction methods.We synchronously collect the defocus sequence images of the object,and then calculate the three-dimensional shape of the object according to the conjugate relationship between the object images.SFF has the advantages of non-contact,long-distance measurement,and no damage to the object.At present,we mainly obtain the defocus images required in SFF by moving the object plane.This will make it impossible for us to reconstruct immovable targets,such as easily damaged and deformable objects.Based on studying the relationship between the defocus image and the height of the measured object,we adopted the method of moving the sensor plane at equal intervals to obtain the defocus sequence image and proposed a three-dimensional reconstruction method based on the plane scanning of the sensor.We have proposed a focus evaluation algorithm with high focus resolution and completed the theoretical simulation and experimental test of the three-dimensional reconstruction of the object.Our main work is as follows:1)We first analyzed the imaging model of the defocus optical system based on geometric optics and diffractive optics theory,and then established the relationship between the defocus image and the defocus distance.Finally,through the object-image relationship,we established a mathematical model for calculating the three-dimensional depth value of the object based on the defocus distance.2)We proposed a high-resolution focus measure algorithm combining the Laplacian operator and discrete cosine transform based on studying the traditional focus measure operators,and established the calculation principle of the new algorithm.3)We obtained the simulated defocus sequence image through the convolution operation of the defocused point spread function of the microscope system and the accurate model of the object.We have created the simulation verification of the focus measure operators and the 3D topography reconstruction technology based on the determined defocus sequence images.The results shown that in the microscopic system of M●100,NA●1.2,the steepness and peak sensitivity of the focus evaluation function curve in this paper are at least higher than the traditional method with 0.106 and 0.82;the root mean square error of the three-dimensional reconstruction results can reach 0.1(?)m.4)We built an experimental platform for three-dimensional topography construction and obtained defocused sequence images by using a high-precision displacement platform to drive the high bit depth camera to move at equal intervals along the optical axis.We completed the experimental verification of the focus evaluation function and the construction of the three-dimensional topography based on the acquired defocus sequence images.In this paper,the steepness and peak sensitivity of the focus evaluation function curve are at least 0.095 and 0.424 higher than the traditional method;In the imaging system F ●2.4,f ●8mm,the root mean square error of the reconstruction result is less than 0.8mm for the plane,inclined and curved imaging targets of size 80mm(?)50mm.Through the research and improvement of the focus shape restoration technology,this paper has laid the foundation for the three-dimensional shape measurement of the object,which has certain reference value.