일반 디지털카메라를 이용하여 표정점과 기선길이의 변화에 따른 3 차원 수치사진측량의 정확도 연구

Abstract

Photogrammetry is defined by the American Society of Photogrammetry as the art, science, and technology of obtaining reliable information about physical objects and the environment through processes of recording, measuring, and interpreting photographic images and patterns of recorded radiant electromagnetic energy and other phenomena. In the photogrammetry, it is very expensive to conserve the film and process images using original surveying camera. Fortunately digital camera can solved such problems and also can increase the quality of the image. So using digital images, we can decrease the cost and it is easy to save images with good quality. It also has a good point that can immediately check the image. According to this, recently many researches have been performed using digital camera to generate 3D model. In the process of generating 3D model, there are many errors need to be rectified. In this study, to generate more precise digital elevation model, we will use many cases of control point and different overlay area between images. To do this, we first take images from the plaster cast using general digital camera, and then using the image station program perform interior orientation, relative orientation, and exterior orientation. Interior orientation is the reconstruction of a bundle of image rays with respect to the projection center. The geometric influence of the lens system is also calibrated as part of the interior orientation process. Relative orientation is the recovery of the position and orientation of one imaging system relative to another from correspondences between two or more ray pairs. In absolute orientation, the ground coordinates of all control points must be first input to the computer. The operator then places the reference mark stereoscopically on corresponding images of the ground control points. Through the above process we can generate the DEM. To estimate the accuracy of the DEM, we used three method. First one is that we compared the precise of the DEM generated in different number of control point. After this, we knew that the precise of the DEM is more correct when the number of control point is 24 and we also found that if the control points are more than 24, there is no obvious change in the accuracy. Second one is that we compared the precise of the DEM generated in different overlay area between images and then we also knew that the precise of the DEM is more correct when the overlay area accounts for 63%. Finally, we compared the accuracy of the DEM generated in different distances between camera and object, and we knew that the proper overlay area is 63% when the distances are 1.22m and 1.5m between the camera and object respectively.