| Handwriting input system and interactive digital whiteboard and other products have been widely used in various fields. A plane positioning technology is used to detect exact location of contact in the plane. with the rapid development of these products technology, the study on the method of plane positioning is of great importance and practical significance.A new plane positioning method based on coding and image recognition is proposed , and a lower cost simple embedded plane positioning system is designed in this paper, comparing with the traditional plane positioning principles and researching on bar code encoding principle and digital image recognition theory. The main research works is as follows:(1) Part of the overall system design, the embedded system structure scheme is designed, by considering PXA270 development board as the hardware platform, Linux as the operating system and coordinates recognition software based on Qt/E as application, and a feasibility analysis is carried out for the overall system design. (2) Part of coding plane design, two schemes of plane are discussed design and corresponding decoding scheme based on two-dimensional bar code encoding technology. (3) Part of the positioning algorithm design, a plane coordinate recognition algorithm is proposed ,by considering plane coding and image recognition, combinating digital image processing theory with plane coding scheme. (4) The process of embedded Linux system construction and transplantion, image acquisition through USB camera based on Video4Linux, image display and BMP format files storage based on Qt/E are also detailed introduced. (5)A coordinates recognition software based on Qt/E is designed that can be used for the necessary image pre-processing for the acquired images from two-dimensional bar code, such as the gray transformation, median filter and binarization, and also be used for the recognization of coding plane coordinates.Finally, the correctness of this coordinate recognition algorithm is verified through a error experiment. Meanwhile, the causes of errors are analized in detail and some improved methods are proposed. Experiment results shows that this theoretieally correct and practically feasible scheme could play an important role on the related products development. |
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