隨著網際網路的發達與虛擬實境技術(Virtual Reality)的進步，許多博物館致力於推展數位化典藏虛擬展示，如何有效數位化文物並建立逼真的虛擬展示是許多研究致力的方向。相對於傳統的三維圖學技術，影像式描繪技術可以提供更逼真的虛擬展示效果，但影像式描繪技術往往會遭遇到資料量龐大的問題。本文基於增添式環場技術(Augmented Panorama)，採用最新的H.264/AVC視訊壓縮技術減少環物影片(Object Movie)的資料量，並且解決環物影片與環場影像需要透明度資訊來做融合(alpha blending)的問題，並進一步利用透明度資訊改善壓縮與解壓縮的效能。最後，我們實做的解碼器結合多層暫存(multi-layer cache)機制以達成網路虛擬博物館即時互動(Just-In-Time)的目標。實驗結果顯示，我們的虛擬博物館系統播放經過H.264/AVC壓縮後的環物影片仍可以達到15 fps以上的效能，同時環物影片的壓縮率也達到80:1以上，大幅降低虛擬博物館資料量。此外，壓縮的時間也比H.264/AVC reference model software 9.0加快了40%。

With the progress of the internet and virtual reality technology, a lot of museum start to build virtual exhibitions based on their digital archives. However, how to effectively reconstruct 3D model of artifacts and to build a realistic exhibition are still problem. Recently, image-based rendering technology provides a high visual quality and realistic approach to construct virtual museums. Among these image-based approaches, augmented panorama augments a panorama with object movies in a visually 3D-consistent way to present a virtual museum of exhibits and exhibition rooms. Such approach also can provide photo-realistic visualization of exhibits and real-time interaction between the visitors and the virtual museum. However, the augmented panorama is rarely used in the internet because of the enormous amount of image data. To solve this problem, we adopt H.264/AVC video codec for compressing object movies. To compress object movies by using H.264, the first step is to reorder the two dimensional images of object movies to one dimensional image sequence. With consideration of the property of the object movie, we propose an image clustering algorithm to rearrange the images of object movies. To further increase the decompression performance, we propose a multi-layer caching structure which can make users possible to interact with museum exhibits in an intuitive and just-in-time (JIT) manner. Experimental results show that the compression ratio of object movie is around 80:1, and frame rate is still above 15 fps. Moreover, compared with reference model software 9.0, the compressing time is saved around 40%.

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