以視訊影像進行三維房屋模型實景紋理敷貼之研究

Producing Realistic Building Texture Using Video Mosaic

陳正軒(Cheng-Hsuan Chen)

指導教授 ： 蔡富安

國立中央大學/工學院/土木工程學系/碩士(2006年)

摘要

在三維視覺展示系統的建置中，房屋模型的建立目前已有成熟的技術，但為達到更真實的效果，還須有實景紋理影像之敷貼。利用影像序列 (video sequence) 作為紋理影像來源是一快速方便的方法。而製作過程中遇到單張影像無法涵蓋整棟建物牆面時，就必須由多張影像鑲嵌而成。此外拍攝過程中遇到遮蔽物時，還需有遮蔽效應處理機制以去除及填補遮蔽之區域。最後製作完成之實景影像要經過處理方能成為適合敷貼至模型之影像。

本研究之目的在於如何利用影像序列以半自動化方式，建立完整之紋理影像並敷貼至模型上。研究方法首先對影像進行紋理校正以降低不同影像間差異來達到降低影像鑲嵌之困難度，稍後亦可直接敷貼至模型。遮蔽效應則透過影像形態學運算，當影像具對稱性時可自動計算鏡射軸進行鏡射填補，搭配GI (Greenness Index) 加強遮蔽偵測能力；無法鏡射填補區域則以鄰近像元灰度值平均填補。最後將所有紋理影像敷貼至模型，在三維虛擬空間中展示敷貼成果。

關鍵字

視訊影像序列 ； 影像鑲嵌 ； 遮蔽效應 ； 模型敷貼

並列摘要

In order to make more realist visualization of 3D building models, the generated scenes should have texture of building facades in addition to the geometry of buildings. Using video sequences as the sources of realist texture is an effective approach. However, a few issues must be addressed in using video sequences for texture mapping in 3D visualization. If a single video frame can not cover the entire wall, individual frames need to be merged correctly to generate a complete image. When foreign objects, like trees, block the target facade, they need to be removed and the blocked areas should be recovered. Also, complete video mosaics need to be mapped onto corresponding building models.

This study developed a procedure to create texture mosaicking images semi-automatically from close-ranged video sequences for photo-realistic texture mapping of building models in 3D visualization applications. The first step was to correct geometry of images. It not only improved the mosaicking, but also facilitated the mapping transformation. The mosaicking was done using interest points detected with corner detecting algorithms and matched with distance-filtering and Normalized Cross Correlation operator. In the developed system, image morphology was used to identity mirroring axis for recovering blocked areas automatically. The resultant building models should have more accurate texture information and improved the reality and practicality of cyber city implementation

並列關鍵字

Texture Mapping ； Image Mosaic ； Video Sequence

參考文獻

傅秉綱，三維建物模型表面影像敷貼自動化之研究，國立成功大學測量工程研究所碩士論文，2002。

Ackermann, F., Digital Image Correlation : Performance and Potential Application in Photogrammetry, Photogrammetric Record, 11(64):429-439, 1984.

Althof, R.J., M.G.J. Wind, J.T. Dobbins, A rapid and automatic image registration algorithm with subpixel accuracy, IEEE Transactions on Medical Imaging,16:308–316, 1997.

Chen, Q., M. Defrise, F. Deconinck, Symmetric phase-only matched filtering of Fourier–Mellin transform for image registration and recognition, IEEE Transactions on Pattern Analysis and Machine Intellingence 16:1156–1168, 1994.

Comaniciu, D. and P. Meer, Robust analysis of feature spaces color image segmentation, Proc. of IEEE Conf. Computer Vision and Pattern Recognitio:750-755, 1997.