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http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/31318
標題: | 從影像中擷取動態資訊以達到追蹤控制與影像里程計的技術與發展 Development of Visual Tracking Control and Visual Odometry from Dynamic Information Acquired through Sequential Images |
作者: | Jun-An Ding 丁俊安 |
指導教授: | 連豊力(Feng-Li Lian) |
關鍵字: | 影像追蹤,影像誤差,追蹤延遲,旋轉傾斜平台,影像里程計,絕對平均誤差,後處理, Visual tracking,image error,tracking delay,pan tilt unit,visual odometry,absolute mean error,post-processing, |
出版年 : | 2011 |
學位: | 碩士 |
摘要: | 影像追蹤是讓目標物保持在影像中的指定位置,通常是在畫面的中心點。首先利用影像處理偵測出目標物在影像中的位置,並移動相機讓目標物在影像的中心點位置,這樣一來就達成影像追蹤。但是當目標物是動態物體時,且系統沒有預測目標物的動作,那麼目標物不會在影像的中心點位置,而一直會和影像中心點有距離差,這個距離差稱為影像誤差,因為目標物的動態所造成的影像誤差稱為追蹤延遲。因此本論文提出四種運動模型來預測目標物的動作,以克服追蹤延遲並降低影像誤差。最後實驗結果顯示有加入預測器的效能比沒有加入預測器的要好。
近年來對自動駕駛的研究越來越熱門,而自動駕駛的研究之一是正確估測出車子的絕對位置,可以利用影像里程計來估測出車子行徑的路徑,就可以得知車子的絕對位置。 影像里程計的目標是從錄下來的影像去估測出車子移動的路徑,其中相機裝在車子上。在車子移動時相機也在錄影,藉由分析影像上的變化,估測出車子的路徑。然而一般相機是投影的感測器(projective sensor),因此只能偵測出影像的變化,而不能偵測相機真正的移動路徑。所以本論文在影像的特定位置,利用平均絕對誤差找出像素的位移量,並把像素位移量轉換成相機的動作以估測出車子的路徑。實驗結果顯示使用提出的方式來估測路徑和真正車子的移動路徑很接近。 Visual tracking is to maintain the target at a specific location in the image by moving the camera. Usually, the specific location is the center of the image frame. At first, the target position is detected by image processing in the image frame. Then, the camera is moved to maintain the target in the image center. This way, visual tracking is achieved. However, if the target is dynamic and the system is not predicting target motions, the target will not be in the image center. The target position will always be off from the image center. This offset is called image error. The image errors caused by target motion is called tracking delay. Therefore, this thesis proposed four motion models to predict the target motion in order to overcome the tracking delay and reduce the image error. The experimental results show that the tracking performance of a predictive system is better than a non-predictive system. Research on autonomous navigation has been more popular in recent years. One of the autonomous navigation issues is accurately estimating a vehicle’s global location. Therefore, by using visual odometry to estimate a vehicle path, a vehicle’s global location can be found. The aim of visual odometry is to estimate a vehicle path from captured images. A camera is mounted on a vehicle, and then the camera captures images when the vehicle is moving. Finally, visual odometry estimates the vehicle path from detecting the differences in captured images. However, the standard camera is a projective sensor; it detects only the image change but not the actual camera motion. Thus, this thesis detects the pixel displacement on a special location by using mean absolute error method. Then, the vehicle path is estimated by converting pixel displacement to camera motion. The experimental results show the estimated vehicle path is close to the actual vehicle path by using the proposed method. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/31318 |
全文授權: | 有償授權 |
顯示於系所單位: | 電機工程學系 |
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