Foot Three-dimensional Measurement System Based On Multi-nodes Laser Speckle Projection

Structured light three-dimensional(3D)measurement technology has widely applied in the fields of industrial inspection and intelligent manufacture,with the advantages of noncontact,low cost,high precision,etc.At present,the 3D measurement equipment has been developed extensively for the human foot,where two measuring types,the laser line scanning and structured light surface scanning,are mainly used.They are limited by time-consuming data acquisition and high-cost equipment.This dissertation focuses on the research of human foot metrology with structured light 3D measurement,meanwhile,a multi-nodes human foot 3D measuring system based on laser speckle illumination has been developed.It is composed of low-cost laser speckle emitting devices and cameras.Multi-nodes synchronous acquisition can save capturing time significantly.The main works includes:Firstly,a laser speckle emission device for 3D measuring human foot is proposed,which consists of a laser module,a frosted glass and a sleeve.The size of the laser speckle particles can be controlled by adjusting the distance between the laser module and the frosted glass.For building a full illumination coverage with speckle pattern in the measurement space,multiple sets of laser speckle emitting devices are arranged reasonably.This low-cost laser speckle emitting device is easy to manufacture,that is suitable for generating speckle pattern for 3D foot measurement system.Secondly,the key techniques of foot 3D measurement based on speckle illumination is studied.According to the requirements for foot measurement,the laser is used to generate speckle pattern illumination,and binocular cameras form a stereoscopic vision system to acquire the modulation image.The system calibration parameters are utilized to perform epipolar line correction,and the corresponding points are quickly matched with the constraint conditions.Then 3D coordinates can be calculated with these calibration parameters and corresponding points.In order to obtain complete foot 3D information,the system with multisensors can simultaneously acquiring foot 3D data from multiple angles,which can be aligned automatically with the calibration parameter of multiple sensors.Hereafter,by using the iterative closest point algorithm to further refine,a high-quality whole 3D foot point cloud is finally obtained.Thirdly,the hardware and software for the foot 3D measurement system are constructed according to the above principles.The contents and functions of the software modules are introduced based on the open source image processing library OpenCV and the point cloud processing library PCL,where the processes of multi-node sensor synchronous acquisition,calibration,Three-dimensional measurement,three-dimensional point cloud processing and display have been integrated.The system achieves 3D foot data acquisition in millisecond,which can be used to further extract the foot dimensions information for the applications of foot type analysis,individualized footwear manufacturing,etc.