Three-Dimensional Coordinates of an Animal Body Ror Analysis of Heat and Mass Transfer at the Body Surface

为了利用光学测距方法和数字图像处理技术测量动物身体的三维坐标，研制了一套仪器系统和计算机程序。该系统由电视摄像机、录像机、监控电视、图像处理单元、电子计算机单元和激光单元组成，用电视摄像机在激光照射下拍摄了3只活重分别为27、65和88公斤的填充猪的图像。将图像传输到计算机，并用图像处理方法进行分析。根据摄影测量原理，从图像数据中获取猪体表面各点的三维坐标。利用计算机图形学方法中的透视投影变换，将27公斤重的猪体表面由13224个面片组成，然后用透视投影变换将其立体显示为多面体。利用边缘搜索技术可以很容易地检测出多面体猪体的轮廓线，猪体的辐射换热形状因子与用立体角投影法变换的轮廓线内的面积有关。直接入射到猪体上的太阳辐射取决于多面体猪体的表面积，通过平行投影变换得到的三维坐标对分析猪体表面的传热传质是有用的。在此之后，目前的程序将适用于其他动物。

An instrument system and computer programs were developed in order to measure the three-dimensional coordinates of an animal body by using the optical range sensing method and digital image processing techniques. The system was composed of a television camera, a video tape recorder, a monitor television, an image processing unit, an electronic micro-computer unit and a laser-light unit.Images of three stuffed pigs (27,65 and 88 kg in live-weight) were taken with the TV camera under projecting rays of laser-light on them. The images were transmitted to the computer and were analyzed by the image processing method. Three-dimensional coordinates of points at the pig body surface wereescalated based on the principle of photogrammetry from the image data. The accuracy of these coordinates was satisfactory.A pig body was reconstructed by small triangular patches, for example 27 kg pig surface was made of 13224 patches and then was stereo-graphically displayed as polyhedron with the perspective-projection transformation, the one of computer graphics methods. A contour line of a polyhedric pig was easily detected with the edge-search technique.A pig's configuration factor for radiant for radiant heat exchange is related to the area within the contour line that is transformed with the solid-angle projection method. Direct solar radiation incident on a pig body is dependent on the surface area of a polyhedric pig that is transformed with the parallel projection.The three-dimensional coordinates obtained by this study are useful for the analysis heat and mass transfer at the pig body surface. The present procedures will be applied to other animals after this.