Research On Contend-Based Image Compressing Method For Wireless Sensor Networks

Because of the lack of sensor node storage capacity and transmission bandwidth, it is restricted for applying traditional video compression algorithms into wireless multimedia sensor networks (WMSNs). For this reason, this paper presented a content-based video compression algorithm, which combined the computer vision technology with characteristics of WMSNs, reconstruct the information about object's structure and motion parameters within the monitoring scene by the means of image sequence processing and analyzing, and then encoded the information so as to achieve the purpose of video compression.Aimed at current problems of high computation cost and poor convergence performance during Shape From Shading (SFS), a mesh-based resolution was proposed which divided the original image into several regions by the means of image preprocessing and region segmentation, and transformed them into triangular mesh, then established equations with regard to each vertex of the mesh in three-dimensional space based on Lambert law, finally straightly applied the result computing by least squares method form the equations to the graphic pipeline of real-time three-dimensional render engine such as OpenGL or DirectX to accomplish the model reconstruction and rendering. The results of simulation show that the method is of convenient calculations and could reconstruct the original model realistically, and the standard deviation of projection distance between reconstruction results and original image is less than 2.7 pixels.According to computer vision techniques of optical-flow reconstruction, feature tracking and motion estimation, a content-based image sequence compression method is designed applicable to wireless sensor networks. Analysis, identification and coding operation are processed while images are collected in the sensor end-points, and the result is sent to browser in incremental manner through multi-hop routing. Finally, the scene reconstruct by the means of computer graphics modeling and rendering techniques, in order to complete the video compression.Finally, a content-based wireless sensor network video compression algorithm simulation system was designed. The system verified feasibility of the studied algorithm in wireless sensor networks application.