Panoramic Virtual Field Geological Information System Based On RIA

Geological Information System is a cross-disciplinary of computer science, geology and cartography, etc. In recent years, Geological Information System has developped rapidly. It has implemented the share of geoscience data and offered decision support for geological workers. With the rapid development of related technology, people don't satisfy general browsing mode in two-dimensions of images and texts any more. They request a real-time system with high visualization and interactivity. In the background of the putting forward of the idea of digital earth and the implementation of digital China, considersing about the problem of present Geological Information System, the author proposes the idea of panoramic Geological Information System and elaborates on the theory and the methods from the basic theory, technology system and application studies. The panoramic Geological Information System software engineering is also suggested in this thesis. At the end the thesis, the author implements a three-dimension panoramic virtual field Geological Information System for the field geological teaching and studying base of Jinlin University in XingCheng as a demonstration of panoramic Geologcial Inforamtion System. In the demonstration sytem, the funciton of three-dimension roam is integrated to the present system, which could manage, analyze and manipulate the panoramic images of the system. The contribution can promote the cross-disciplinary studies and support the field geological researchs, mineral prospecting and field geological teaching, etc.In recent years, the improvement on performance and the reduction in price of the devices such as digital camera, computer, network, storage device, GPS and laser scan machine prepare the hardware base for the construction of panoramic Geological Information System, and the rapid development of the technology of network, Virtual Reality (VR) and the theory of Geological Information System prepare the technology base for it.VR is a new integrated information technology of recent years, which enable the user to observe and manipulate the virtual world interactively through the interactive User Interface (UI) implemented using computer. The starting out of the technology of VR in our country is late, but the related departments and the scientists have paid high attentions to it. Because of the features of real-time, immersion, interactivity and imagination, VR has been applied in many fields such as aeronautics and astronautics, machinery design, scientific computing, film amusement, chemical medicine and military training, etc. With the putting forward of the idea of Digital Earth and the implementaion of digital China, VR has been applied in the filed of geology in some degree. For example, some applications such as three-dimention geological modeling and the visualization of geological information have all greatly promoted the visulization of present system. There are two methods to implement VR, which are Model-Based Method and Image-Based Rendering (IBR). Most geological applications of VR are constructed by Model-Based Method.This method involves complicated course of eliminating hidden surfaces and shading computation, so it is a knotty problem to implement real-time rendering of realistic images on personal computers and release through Internet. IBR is one of the hottest technologies of graphics. It is also the most advanced method of generating realistic images, whose core idea is trying to avoid complicated modeling. Compared with traditional Model-Based Method, IBR has many advantages. For example, its rendering is only related with the resolution of the frame and has nothing to do with the complexity of scene. The image could be synthetized by computer or captured by photo in real world or even be the mixture of both. The computation cost is not so large and it demands for less computer resource. So it enables the general workstation or personal computer to display complicated scene in real time. Because of the advantages above, IBR could construct virtual environment which is nearer to the real world and offers a new efficient way to implement VR.Because of the urgent demand and good prospects, IBR has developped rapidly since it was suggested. According to the motion mode of virtual camera, the technology of IBR could be devided into five types, which include panoramic image technology, stereoscopic vision technology, plenoptic function technology, optical flow field technology and view interpolation technology. As a way of storing and displaying of IBR, panorama has many advantages. Firstly, the data is small to ensure the rendering speed. Secondly, panoram adopts real photos to display the virtual environgment, which could not only rebuild the vision information of the real scene but also simulate user's feeling to some degree. Lastly, the quality of the virtual environment based on panorama is better than the one based on modeling. So, the technology of panorama has good application prospects in many fields.There are lots of observation points in the virtual field Geological Information System, so the amount of images is very large. And the user of the system needn't the interactivity for the certain object of virtual environment but only roam. Considering those factors, the author suggests the solution of constructing virtual field geological environment based on the technology of IBR with panorama.Rich Internet Applications (RIA) is the core technology of Web2.0, and its destination is to combine the responding speed of desktop application with the extension of Web application. With RIA, developers could not only arrange the client programs of C/S on browser but also get much higher performances than traditional HTML pages. Flex and Asynchronous JavaScript and XML (Ajax) are both the main technology of RIA. Flex has great advantages on interactivity and interface displaying, and Ajax could shorten responding time through its technology of asynchronous so as to improve user experiences. If the advantages of both could be combined to solve the problem of slow image loading speed caused by constructing VR, the visualization and interactivity of present Geological Information System could be improved greatly.The technology of VR could improve the visualization of present Geological Information System greatly, but the problem such as real-time, interactivity and the bottle-neck of image loading speed caused by constructing VR should be solved firstly. Through constructing panoramic VR, the thesis improves the visualization of present Geological Information System. By the technology of RIA, the thesis solves the problem of real-time, interactivity and the bottle-neck of image loading speed during the course of constructing. Theory analysis and the practice prove the solution of constructing the three-dimention panoramic virtual field Geological Information System based on RIA to be feasible, efficient and innovative. The thesis mainly studies the integrating technology of RIA, VR and Geological Information System. There are no related studies at present.The main contributions and innovations of this thesis are listed as followings:1. The thesis integrates the technology of VR with the Geological Information System using panoramic images and implements a panoramic virtual field Geological Information System.The technology of virtual roam is one of the hottest points in the field of VR. At present, most VR applications of geology adopt traditional Model-Based Method, which could improve the visualization and reality efficiently. However, because the method involves complicated computation of geometry modeling, image loading speed becomes the bottle-neck of this type of system while being released through Internet. It is the main reason why it is difficult to integrate the technology of VR to Geological Information System. The author implements a virtual field Geological Information System based on IBR with panoramic images, in which user could roam randomly in the virtual environment. This is the first Geological Information System with the function of virtual roam, which improves the interactivity and visualization of present Geological Information System.2. The author puts forward the idea of panoramic Geological Information System and discusses its theory and method systematically.Having analyzed the disadvantages of present integration of VR and Geological Information System and demonstrated the related technologies basis, the author puts forward the idea of panoramic Geological Information System and introduces the study objects, which include the basic theory, technology system and application study. The basic theory mainly includes the concept, architecture, functions and features of panoramic Geological Information System. The technology system mainly introduces the whole constructing steps from the acquisition and pretreatment of images, the construction of panoramic image database to the visual browsing. The application study mainly discusses the application field and the application method.3. In this thesis, a panoramic image acquisition system is designed and developed. The work group which the author belongs to designs and develops a vehicle-carriedpanoramic image acquisition system (PIAS) completely independently. The system is controlled by GPS and could capture panoramic images efficiently according to certain distance during the course of driving. Compared with the traditional handwork, it improves the capture efficiency without reducing the data precision. Patent of utility model has been granted to the system.4. The technology of tiles is adopted to improve the efficiency of rendering and the image loading speed.The technology of VR could improve the visualization of the present Geological Information System, but the problem of interactivity, real-time and the image loading speed caused by constructing VR must be solved firstly. PV3D is adopted in the thesis, which is an open source three-dimension engine tool. The three-dimension virtual scene could be constructed based on a cubic model. However, because of the limitation of the algorithm of PV3D, six images on the different sides of the cube have to be loaded together when constructing the virtual scene, which will increase the computation and make the efficiency fall down. Having analyzed the core rendering algorithm of PV3D, the author modifies its core codes. Each bitmap on the side of the cube is separated to four parts. When the virtual scene is constructed, only the tiles in the view port are rendered, which could decrease the computation greatly and improve the rendering efficiency.5. The asynchronous transmission technology of Ajax is adopted to improve the userexperiences.In the thesis, Ajax is adopted in the thesis, too. Ajax is one of the core technologies of Web2.0. Through the asynchronous transmission technology of Ajax, the surrounding tiles of current view port will be transmitted asynchronously when the network load is light, and the user might not feeling the action of image loading. So, the user experience is improved.It has great significance to study the technology of panoramic virtual field Geological Information System. Planet remote sensing and aeronautic remote sensing are two levels of describing the earth information at present, and the panorama is the level of ground remote sensing in fact, the solution of which is much higher than the other two. So, Planet remote sensing, aeronautic remote sensing and the panoramic form a perfect images information description system of the earth. It has great significance to construct panoramic Geological Information System. Firstly, panoramic Geological Information System could enlarge the natural resource information of our country and offer filed geological information in detail. Secondly, the putting forward of the panoramic Geological Information System suggests a new thinking for the development of Geological Information System. The technology architecture improves the visualization, interactivity and the bottle-neck of real-time, so it prompts the further progress of the implementation of digital China. Thirdly, the system implements the geological information share and lays the foundation of the further resource investigation and cooperation. Lastly, the long time accumulation of filed geological information could form filed geological repository.Panoramic filed Geological Information System is the combination of the technologies of panoramic images, spatial database and graphics. It is a tendency of spatial information system. Because panorama could offer images with higher solution than remote sensing, the combination of panorama and remote sensing has great application potential in many filed such as natural resource investigation, universal geology education, the evaluation of geological environment and geological hazard prevention, etc. At present, the technology of 3D has been applied in the geological research. Adding Panoramic Information System (PIS) into present technology of 3S could offers more detailed spatial information service.Three-dimension panoramic Geological Information System could be applied to many research filed, and the thesis offers the technology support for related integration of RIA, three-dimension panoramic VR and various system in different fileds. The technology of tiles and Ajax also suggest a new thinking for the development of VR.