Embedded 3D Shape Measurement System On An Compound Coding Method

Three-dimensional measurement technology has been widely used in many occasions,including the detection of industrial parts,VR movie production,3D map navigation,cultural relics and so on.There are a variety of three-dimensional measurement methods,but the structure light measurement method has got the most attention and research with the advantages of large field of view,high precision,controllable coding pattern and good real-time performance.With the development of intelligent manufacturing and the popularization of industrial automation,the production of intelligent devices is developing toward the direction of high speed,high precision,high portability and low power consumption.Therefore,the embedded platform is the best tool for the three-dimensional measurement solutions now.In order to meet the requirements of high-efficiency,high-precision,low-power consumption,and high-automation in practical industrial online three-dimensional measurement,an new method combining of binary coding and sinusoidal coding is proposed in this paper.With same resolution,the number of projected patterns is dramatically reduced and we can get the absolute phase quickly.Finally,an embedded three-dimensional measurement system based on the AM572 x multi-core platform is provided.The main research contents and achievements include the following aspects:1.Analysis of existing structured light coding strategy,a hybrid coding method based on binary coding and sinusoidal coding is proposed.In the coding part,in order to reduce the coding error caused by the mutation of grey intensity,we optimize an arrangement of 0,1 marking area and coding area,under the limitation of minimizing the number of boundary and an smooth transition between the two area,to figure out the problem.In the decoding part,we develop a new filtering strategy,extract the sinusoidal pattern in each period through the binary coding,which dramatically improve filter speed.What is more,we map the high dimensional vector into a real number and get the linear phase,which eliminate the cumulative errors and avoid calculating the polar equation.Therefore,a better stereo matching efficiency is got.Lastly,we discuss and verify the variable-frequency characteristics of the coding method proposed in the paper.Without changing the resolution and number of coding patterns,the measurement accuracy can be improved when adding the number of sinusoidal stripe in the patterns.2.We set up a communication program framework between ARM and DSP with IPC mechanism in the 3D software system.It is easily to control the peripherals for ARM,a better choice is put the work of camera acquisition,memory control,file reading on the ARM core.Considering high-speed computing advantage of DSP,we transplant the decoding program and binocular stereo matching program on DSP core.Furthermore,to enhance the completeness of the system,we display the point cloud data on the LCD touch screen with interface of OPENGL ES 2.0 in QT.3.An embedded system based on AM572 x platform is established and a plaster statue is reconstructed in the experiment.As a result,the correctness and feasibility of the coding strategy and the embedded system has been verified.