Development of a Web VR-GIS Using Stereo Vision

This research continues the development of the integrated Web-GIS created by former studies and expands new functions including the 3D model reconstruction, display and internet virtual reality. In the reconstruction of 3D models, we applied stereo vision to calculate the depth information, determined the camera intrinsic parameters by camera calibration, and reconstruct 3D models by projective reconstruction based on simple geometry of pinhole camera. The segmentation of 3D objects in a scene was based on the disparity estimated from image pairs. We also developed the post-processing tools for mending and filtering of the segmented 3D objects. The multi-view objects were merged by using the SIFT method to detect the corresponding feature points of images from different views, and the matched points are used for the registration and merging of the two 3D objects. Following the object registration of different views, the data points of 3D objects are mapped into the cylindrical surface. The Delaunay triangulation method is then applied to triangulate the points on the surface and subsequently completes the merged model based on the registered feature points. This procedure simplifies the 3D meshing problem to a 2D problem and thus 2D image processing algorithms can be employed for the computation of 3D reconstruction. To visualize the 3D models in the internet environment, the virtual reality modeling language X3D was used to render and display the 3D objects in real-time. The X3D models, together with the panoramic images, can be linked to the GIS system to form a virtual reality GIS (VRGIS) for internet access. The developed VRGIS thus allows users to interactively navigate through scenes in virtual reality.