利用視訊建構影像接合圖之研究

Abstract

利用多張影像建構環場影像在電腦視覺領域內一直是重要的研究課題，不同於傳統在建立環場接合影像時的諸多限制，例如限制平面場景或攝影機做純旋轉運動，本研究利用流形投影的概念來建構影像接合圖，並且採用贏者更新策略快速區塊比對演算法來進行運動估測，使得本論文發展之即時遠距影像掃描系統得以在任意攝影機運動與任意場景下進行即時環場影像接合。此外，由於長軸畫在數位化的過程中往往十分沒有效率而且繁複，針對此一問題，在本論文裡我們利用所發展之即時遠距影像掃描系統，在等速度與等方向攝影機運動條件限制下分別對長軸畫的不同部份做取像，使得所得到的區域接合影像皆符合Linear Pushbroom Camera Model，並且利用此一模型，找出不同區域接合影像間的幾何對應關係，再用此一關係來將長軸畫做重建。為了達到自動化重建的目的，在本論文中我們將自動找尋與建立區域接合影像間特徵點一對一的點對應關係，以及利用多層解析度顏色融合技術將區域接合影像於不同頻帶內給予不同權重做接合後，再將長軸畫做重建，以減少區域接合影像間色彩的差異在長軸畫重建時所造成的影響。經由許多的實驗結果，証實了本論文提出的方法在長軸畫的重建上具有效率與可行性。Integrating multiple images taken with perspective cameras for building a panoramic mosaic is an important research topic in computer vision. Several limitations, such as restricted camera motions or scene structures, have been put to be necessary conditions for building panoramic mosaics in some researches. In this thesis, we use the manifold projection model to create panoramic mosaics from videos, and the winner-update strategy for block matching is adopted to speed up the estimation of camera motion. By doing so, we have developed a real-time distance-scanning system for mosaic construction that is suitable for on-line hand-held camera motions and unconstrained scene structures. In addition, the processes for digitalizing wide-field drawings are usually inefficient and complicated. To simplify this problem, we use a real-time distance-scanning system consisting of a video camera moving along a track with constant velocity and constant camera direction to generate a LP-mosaic, which can be modeled as a linear pushbroom camera. In particular, we have conducted mathematical models for the case that multiple linear-pushbroom cameras are used to take a planar scene, which is a relatively unexplored area and has not been well studied in the past. An automatic method for finding matching corners between a pair of LP-mosaic images is adopted, and a multiresolution color blending technique is performed to seamlessly stitch several LP-mosaic images. Good experimental results show the efficiency and feasibility of the proposed method for wide-field drawing reconstruction.