基于DSP嵌入式平臺多路實時視頻拼接技術(shù)
本文選題:全景環(huán)視系統(tǒng) + 嵌入式系統(tǒng); 參考:《上海交通大學(xué)》2013年碩士論文
【摘要】:實時圖像拼接技術(shù)一直以來都是計算機視覺領(lǐng)域的研究熱點之一。近年來隨著汽車電子的發(fā)展,出現(xiàn)了車載環(huán)視技術(shù),可以將汽車周圍的環(huán)境以一幅鳥瞰圖顯示給駕駛者,提高行車安全。實時圖像拼接技術(shù)是實現(xiàn)車載環(huán)視系統(tǒng)的關(guān)鍵。然而,目前有關(guān)圖像拼接的研究大多以PC為實現(xiàn)平臺,鮮見其在車載嵌入式系統(tǒng),比如DSP處理器系統(tǒng)上的實現(xiàn)。 本文針對圖像拼接進行了算法研究,提出了車載實時圖像拼接的系統(tǒng)架構(gòu),,選用SURF算法進行圖像匹配,用RANSAC算法進行圖像拼接并利用加權(quán)平均法進行圖像融合。在核心算法層面,為了改善圖像拼接算法的時間效率,本文在分析了SURF算法原理的基礎(chǔ)上,提出了從方框濾波器權(quán)值,特征點周圍子區(qū)域的選擇以及子區(qū)域內(nèi)Haar小波變換的采樣點范圍三方面進行算法的參數(shù)配置優(yōu)化,并采用控制變量法分析了在不同的SURF參數(shù)配置下,對算法特征點匹配的時效性、準確性和魯棒性等性能的影響,綜合通過仿真實驗結(jié)果,給出了SURF算法參數(shù)的選擇策略。 在系統(tǒng)算法結(jié)構(gòu)層面,通過對實驗結(jié)果的詳細分析,本文對算法進行了逐步改進,采用改進拼接流程和增加配準圖像的方法減小了圖像定位的誤差,并針對環(huán)形鳥瞰拼接的獨特需求,設(shè)計了合適的拼接順序和融合權(quán)值計算方式,改善了圖像的最終顯示效果,同時兼顧了算法的時間效率。改進后的算法具有較高的準確度,融合效果好,能顯示一張完整無縫的環(huán)形圖像,并滿足系統(tǒng)的實時性需要。 在系統(tǒng)實現(xiàn)方面,本文研究了基于TI公司的DaVinci處理器實現(xiàn)一個視頻圖像拼接系統(tǒng),并提出了一個基于DSP系統(tǒng)的軟件系統(tǒng)架構(gòu),在該架構(gòu)下DSP端程序主要負責(zé)圖像拼接的核心算法,ARM端程序主要負責(zé)通過V4L2驅(qū)動控制IO設(shè)備,兩者通過訪問共享內(nèi)存實現(xiàn)圖像數(shù)據(jù)的高效傳遞,并盡可能減少了互斥所引起的程序掛起時間。最后,本文說明了拼接算法在DSP上的實現(xiàn)方案及注意事項,并給出了測試結(jié)果。 相比之前的研究,本課題實現(xiàn)了基于DSP嵌入式系統(tǒng)的全景圖像拼接系統(tǒng),并針對系統(tǒng)實時性的要求對算法進行了相應(yīng)的改進。本文提出的SURF算法參數(shù)選擇策略,可以根據(jù)不同圖像拼接需求調(diào)整算法,例如在針對實時視頻流的拼接上,采用合理的參數(shù)可以在保證SURF算法拼接精度的基礎(chǔ)上,拼接效率提高30%左右。參數(shù)配置理論使得SURF算法能夠更廣泛的應(yīng)用于不同的圖像拼接領(lǐng)域。
[Abstract]:Real-time image mosaic technology has always been one of the hotspots in the field of computer vision. In recent years, with the development of automobile electronics, the technology of vehicle-mounted surround view has emerged, which can display the surrounding environment of the vehicle to the driver with an aerial view to improve the safety of driving. Real-time image stitching is the key to the realization of vehicle-mounted circle view system. However, at present, most of the researches on image mosaic are based on PC, and few of them are implemented on on-board embedded system, such as DSP processor system. In this paper, the algorithm of image mosaic is studied, and the system architecture of vehicle real time image mosaic is proposed. The SURF algorithm is used for image matching, the RANSAC algorithm is used for image stitching and the weighted average method is used for image fusion. At the core algorithm level, in order to improve the time efficiency of image stitching algorithm, based on the analysis of the principle of surf algorithm, the weight value of the filter is proposed. The selection of sub-region around the feature point and the sampling point range of Haar wavelet transform in the sub-region are optimized. The control variable method is used to analyze the different SURF parameter configurations. By synthesizing the simulation results, the selection strategy of the parameters of the surf algorithm is given, which affects the timeliness, accuracy and robustness of the feature point matching of the algorithm. At the structure level of the system algorithm, the algorithm is improved step by analyzing the experimental results in detail, and the error of image location is reduced by improving the stitching process and increasing the registration of images. According to the unique demand of annular bird 's-eye view stitching, a suitable order of stitching and the calculation of fusion weights are designed to improve the final display effect of the image and to take into account the time efficiency of the algorithm. The improved algorithm has high accuracy and good fusion effect. It can display a complete and seamless annular image and meet the real-time needs of the system. In the aspect of system implementation, this paper studies the implementation of a video image mosaic system based on TI's DaVinci processor, and proposes a software architecture based on DSP system. In this framework, the DSP program is mainly responsible for image stitching, and arm program is mainly responsible for controlling IO device through V4L2 driver. Both of them can transfer image data efficiently by accessing shared memory. And minimize the mutex caused by the program hang-up time. Finally, this paper describes the implementation of the splicing algorithm on DSP and points for attention, and gives the test results. Compared with the previous research, this paper implements a panoramic image mosaic system based on DSP embedded system, and improves the algorithm to meet the real-time requirements of the system. The SURF algorithm parameter selection strategy proposed in this paper can adjust the algorithm according to different image mosaic requirements. For example, in the real-time video stream mosaic, reasonable parameters can be used to ensure the accuracy of SURF algorithm stitching. The efficiency of stitching is increased by about 30%. Parameter assignment theory makes the surf algorithm more widely used in different image stitching fields.
【學(xué)位授予單位】:上海交通大學(xué)
【學(xué)位級別】:碩士
【學(xué)位授予年份】:2013
【分類號】:TP368.1;TP391.41
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