High Speed Acquisition of Texture and Optical Property for a 3D object and Application to Preservation of Cultural Heritages

计算机图形技术在电影、电视节目和电脑游戏等领域有许多应用。本研究的方向是获取手头现有物体的纹理和光学特性的方法。第一种方法是获取物体表面的纹理和映射。提出了一种分层匹配方法。第一阶段使用从对象中心到周长的距离直方图，而第二阶段使用到中心的距离。第三阶段采用低分辨率剪影，第四阶段采用高分辨率剪影。结果时间大大缩短，因此一个对象的总时间约为3分钟，因为图像的时间需要20到30秒。第二种方法是利用纹理对纹理匹配而不是轮廓匹配来估计摄像机位置。当由于相机位置估计误差导致配准错误时，在两幅相机图像的重叠区域，一条线会变成两条线。提出了一种利用纹理进行匹配的更精确的配准方法。第三种方法是测量自由曲面物体表面的光学反射特性。表面被分割成具有相同光学性质的区域。摄像机的位置是用来观察一个区域的高光。光学反射可以根据照相图像来测量。最后，将提出的方法应用于一个重要的应用，即文化遗产的保护。我们联系了丰桥市立美术馆，用手持式激光扫描仪对两个泥人进行了扫描。此外，还扫描了两尊佛像。使用数码相机获取纹理并测量光学反射。建立相应的三维CG模型。结果表明，CG复制品对保护因火灾和地震等灾害而减少的文化遗产非常有用。少

Computer Graphics technology has found many applications in such areas as motion pictures, TV programs, and computer gamas. This research is directed toward methods for acquiring textures and optical properties of an existing object on hand.The first method is the one for acquiring textures and mapping on the surface of an object. A hierarchical matching method is proposed. The first stage employs the histogram of the distances to the perimeter from the object center, while the second uses the distance from the center. The third stage employs low-resolution silhouette and the fourth stage uses high resolution silhouette. The resulting time was reduced substantially so that the total time of an object is about three minutes since the time for an image takes 20 to 30 seconds.The second method proposed is on the estimation of camera positions by using texture to texture matching rather than silhouette matching. When mis-registration takes place due to estimation error in camera position, … More a line becomes two lines in the overlapping areas of two camera images. A more exact registration method is proposed that utilizes textures for matching.The third method is concerned with to measure optical reflection properties of the surface of a freeform object. The surface is segmented into regions with the same optical property. A camera is positioned to observe a high light from a region. The optical reflection can be measured based upon a photographic image.Lastly the proposed methods were applied to an important application, preservation of cultural heritages. Toyohashi municipal art museum was contacted and two clay dolls was scanned with a handheld laser scanner. In addition, two Buddizm statues were scanned. A digital camera was used to acquire textures and to measure optical reflection. The corresponding 3D CG models were constructed. It was demonstrated that the resulting CG replicas are useful to preserve cultural heritages which are diminishing due to disasters as fire and earth quakes. Less