Study On The Internal Stereoscopic Measurement Technology

The measurement technology based on internal stereoscopic has been preliminary studied and applied abroad, and is getting more and more attention interiorly. With the CCD (Charge Coupled Device) camera miniaturization and integration of computer hardware, as well as continuous improvement of correlated technologies, internal stereoscopic measurement technology will soon be applied globally for its flexible, rapid, non-contact, precision, high degree of automatization and other characters.This paper focuses on the study of using stereoscopic endoscope as a detect tool, using the images coordinates collected by CCD camera to determine and calculate the spatial relationship of the points, then get the distance information by image points. This technology is used to detect rifled damage of the guns and artillery, and it has qualitative analysis and quantitative measurement for the depth and length of the rifling damage region.Stereoscopic endoscope design is one of the key issues to achieve stereoscopic measurement. The stereoscopic display technology is based on the human binocular stereo vision, and it can not be separated from the normal vision. The author combined stereoscopic visual geometric model, used the principle of Panum area which is fitted to the humans eyes to observe as a basic, calculated the comfort parallax range fitted to the human eyes observation habit, and in accordance with the comfortable observation distance showed in the CRT (Cathode Ray Tube)monitor, estimated the maximum pixel difference, according to this data, derived the magnification, focal length, field of view and other key parameters of the stereoscopic endoscope.The difficult point of the entire detection system is the calibration of the stereoscopic camera, three-dimensional image reconstruction and match. According to the measurement characteristics of the bore and the barrel and the analysis of the on-site environment, it uses a flexible, simple, high-accuracy calibration - Zhang plane calibration, to meet the measurement requirements; at the same time, it brings forward the best edge detector operator of the Canny arithmetic, which is based on adjustable threshold value, so that the image on the edge is clearer, and improves the signal-to-noise ratio. It designs a quick algorithm for gray match of the area and the match of the feature points which are based on the dynamic programming, according to the characteristics points to limit the effective parallax set of the non-characteristics points, and narrows the computational complexity and the search range of the generated parallax space, so the covered area will be identified in a certain extent. This algorithm is simple and practical, the operating speed is fast, and it can achieve a higher match rate for the stereopictures which the edges are clear. It gets good results in experiments.Design and debug the time division stereoscopic display system, it is the first use of FPGA(Field-Programmable Gate Array)technology, and breaches the original shortcomings of the need of the computer software to control, stereopictures flashing, and the poor real-time performance. This technology allows stereoscopic endoscopic images show completely out of the control of the computer, using Verilog HDL (Hardware Description Language) language to achieve a two-way video processing and video transmission control circuit design, in order to achieve video data storage, uses peripheral SDRAM (Synchronous Dynamic Random Access Memory) memory as a frame memory. Use FIFO(First Input First Output) in the FPGA as buffer to storage the input and output pixel data of SDRAM to speed up the pace, so that the output frame rate is up to 100Hz and has a progressive-scan, and also makes the watcher more comfortable.To sum up, the paper completed the study on the internal stereoscopic measurement technology and the development of the system, as well as the measurement of the artillery rifling damage. The paper has a great significance for the development of non-contact optical detection techniques.