In the paper, image pyramid is employed to detect terrain changes and update terrain data step by step. Low-resolution
new image and old DEM are used to quickly acquire elementary detection results by VLL matching at first. The result
may contain many pseudo changes. And then it switches to high-resolution new image to improve and verify the
elementary results with stricter matching and detecting conditions such as more exact template size or thresholds. All
changed parts are detected and updated to obtain up-to-date terrain data. Experimental result shows that terrain change
detection and updating based on VLL matching can achieve updating accuracy with 84.22% and RMSE of 1.6386m.
However, terrain change detection and updating with image pyramid can achieve updating accuracy with 84.44% and
RMSE of 1.6413m, and it obviously improves the accuracy. It can make conclusions that terrain change detection and
updating based on VLL matching is a highly automatic and practical approach to detect terrain changes and update DEM
simultaneously. Terrain change detection and updating with image pyramid can efficiently improve the results of
updating and make the approach more applicable.
3D reconstruction plays an essential role in the documentation and protection of ancient architecture. 3D reconstruction and photogrammetry are mainly used to conserve the datum and restore the 3D model of large-scale ancient architecture in our work. The whole procedure and an algorithm on space polyhedron are investigated in this paper. Firstly lots of conspicuous feature points are laid around the huge granite in order to construct a local and temporary 3D controlling field with sufficiently high precision. And feature points on the granite are obtained by means of photogrammetry. We use DLT (Direct Linear Transform) to calculate coordinates of feature points and accuracy evaluation of all feature points can be obtained simultaneously. A new generation algorithm for spatial convex polyhedron is presented and realized efficiently in our research. And we can get 3D model of the granite. In order to reduce duplicate storage of points and edges of the model, model connection and optimization are performed to complete the modeling process. Realistic material can be attached to the 3D model in 3DMAX. At last rendering and animation of the 3D model are completed and we got the reconstructive model of the granite. We use the approach mentioned above to realize the 3D reconstruction of large-scale ancient architecture successfully.