Three-Dimention Visual Measurement Of Standard Sheet_Metal

The purpose of the computer vision research, which is similar to the research of photogrammetry, is to make computer have visible ability which resembles that of human's eyes and to regain the characters of three-dimensional space through objectives' two-dimensional information in the image. In the traditional methods of photogrammetry, the same image points picked out from multi-images is used to calculate the corresponding space-coordinates using the multi-image fore-intersection. The standard industrial sheet-metal includes plenty information about straight lines and cross points which can help to make three-dimensional measure on it, although the industrial sheetmetal also brings some difficulties to image matching because it lacks textures on its surface.As the wild use of CCD, to obtain the digital images becomes easily and this definitely makes the computer vision and the close-range photogrammetry a further development. Camera calibration is an indispensable step when using the technology of vision inspection to make three-dimensional measurement on objectives. In order to get initial value of the camera parameter, the paper firstly uses 2D-DLT to make a rough calibration, and then to get the precise camera parameters by using bundle adjustment of photogrammetry.In order to extract the image's verge and build the corresponding topological relationship, some standard models have been devised. The model is projected onto the images by the geometrical projection relationship and overlapped with objectives on the image through translation, rotating, shortening and loosening. This provides convenience to image character extraction and it also provides the initial value for the following adjustment-calculation models.Co-linear Equation has been already wild used as the core equation of photogrammetry. In the traditional theory of photogrammetry, the premise of using the Co-linear Equation is to extract the strict same points, and this is quite difficult for complicate industrial sheet metal. The theory of general point phototgrammetry develops the using range of Co-linear Equation from physical points to mathematics points. The use of general point phototgrammetry and corresponding adjustment model can meet good measuring precision and it overcomes the shortcomings of the traditional photogrammetry in the fields of few numbers of observations. What's more, by using general point photogrammetry adjustment model, the character parameters of the curve can be directly worked out.