使用粒子群最佳化微調相機校正參數

Parameter Fine Tuning for Camera Calibration using Particle Swarm Optmization

陳盟鈺(Meng-Yu Chen)

指導教授 ： 林義隆

共同指導教授 ： 鄭志宏(Jyh-Hong Jeng)

義守大學/電機資訊學院/資訊工程學系/碩士(2017年)

摘要

相機校正在影像處理與電腦視覺領域的相關議題中一直扮演著重要的角色，常見的校正方法分為內部校正以及外部校正，兩種皆是為了取得相機的參數，用在影像變形還原，常應用在機器手臂、測量距離等。藉由相機外部參數轉換將真實3D世界座標上的座標資訊轉換成相機影像座標，接著用內部參數將相機影像座標轉換成影像座標，成為一張2D平面影像，而取得這些相機參數屬於最佳化問題，因此我們希望結合粒子群最佳化演算法，提升校正的效果。
本論文參考Open CV 提供的相機校正演算法，實驗的相機是使用約170˚廣角鏡頭相機SJCAM-SJ4000，我們對棋盤格校正板拍攝實驗所需的測試用圖，再分別找出影像中的棋盤格角點座標即我們所謂影像座標，與我們預設的世界座標下去計算出實驗相機之相機參數，含內部參數 、鏡片扭曲參數 、外部參數 ，我們欲使用粒子群最佳化演算法對於這些參數再進行估算，現階段我們考慮先針對鏡片扭曲參數進行估算，期望可以得到較佳的參數使校正後的結果與原始結果相比會有改善。

關鍵字

電腦視覺 ； 相機校正 ； 粒子群最佳化演算法

並列摘要

Camera calibration has played an important role in the field of image processing and computer vision. The common methods for calibration can be divided into internal calibration and external calibration. Both methods can find the parameters of cameras, which can be applied to the field of robotic arm applications, measuring distance and so on. To get an image, first we need to transform the information of 3D world coordinate into camera coordinate by external parameters. Next, use internal parameters to transform camera coordinate into 2D image coordinate, and finally we can get an image. Getting external and internal parameters is labeled as optimization problem. In order to fine tune the parameters, we introduce Particle Swarm Optimization (PSO) method to improve the image quality.
In this thesis, we take camera calibration method provided by OpenCV as our reference. We use wide-angle lens camera to test our method. We take pictures of chessboard corrector plate as our testing images. Find out all the corner coordinates in chessboards of each images. By using those coordinates we find that we can estimate the parameters of the testing camera. The parameters include internal parameters, external parameters, and distortion parameters. We try to fine tune for new parameters using PSO. Experimental results show that we can indeed improve the visual quality a little, although the quantity index, reprojection error, exhibits very little improvement.

並列關鍵字

Computer Vision ； Camera Calibration ； Particle Swarm Optmization

參考文獻

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