內視鏡手術由於具有手術傷口小、病人恢復速度快等優點，在臨床上被廣泛應用。因此近幾年來，在特定的手術上漸漸有取代傳統手術方法的趨勢。儘管內視鏡的應用有許多優點，由於內視鏡的構造與特性，在手術上還是有些不方便的地方。例如為了能看到大範圍區域而使用廣角鏡，反而使得內視鏡的成像會產生扭曲形變的現象，同時也會影響後續的判讀，醫師們需經過一定的訓練才有能力直接判讀扭曲過的影像資訊。
　　因此研究如何透過電腦視覺的技術來協助手術的進行，已經成為很多人研究的重點。除了強化影像的細節外，影像上的校正也是很多人研究的項目。另外，內視鏡在操作上只能在狹窄的空間中移動，限制相當多，因此手術時比較不容易知道目前內視鏡位置與手術部位的相對位置，因此手術導覽系統相顯重要。
　　本論文簡化過去校正內視鏡影像的方法，利用更簡單的數學模型進行校正，縮短計算時間，而且可以得到不錯的結果。另外，透過校正過的影像重建出比較正確的三維物體表面，並且利用三維模型的對位，找到目前內視鏡的位置，讓醫生可以瞭解目前手術工具與骨頭的相對關係，可以對手術做出更詳盡的判斷。

　Because of the minimal incision and faster recovery in clinical treatment, endoscopic surgery has become the most popular surgical type in the past few years. Although it has attractive advantages, endoscopic surgery still has some inevitable drawbacks. For example, in order to get a larger field of view, it utilizes a wide-angle lens and brings lens distortion in the endoscopic imaging. Therefore, if the surgeons are not well trained, it is usually diffcult to determine the organ size or the distance between organs precisely. In this thesis, we tried to develop a computer assistive system to help medical doctors in utilizing the endoscopic system.

　Because the researches based on computer vision are some possible solutions to develop the needed assistive systems, many researches were reported and focused in these fields, such as image enhancement, image calibration and 3D econstruction. Furthermore, the endoscope is operated under limited space, the geometry and relative position of bones are not easy to obtain. Therefore, a navigation system for endoscopic surgery is important.

　In this thesis, we simplified the traditional method in correcting lens distortion, and proposed a simpler mathematic model for lens correction. The new method takes less time and produces very good results. In addition to the conventional shape from shading algorithm for reconstructing 3D surface, we also proposed a new specular correction method which is used to correct the shading in specular regions before reconstruction. The specular problems that are popular in the endoscopic data are effectively resolved and the reconstructed objects become more precise. Besides, we also aligned (or registered) the reconstructed surface to a known CT model and found good correspondence between modalities. Thus, surgeons can get more useful information from the endoscopic images and make more precise decision in clinical practices.

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