| Gravitic and magnetic data are vital in the area of exploration,deep subsurface geology and physical geography research. The trend of their interpretation develop from 2 dimension to 3 dimensiona. But, the 3 dimensional interpretation of data is more complex than 2 dimensional,such as: precision, speed ,the accuracy of computation, software's agility and convenience when constructing geology object, topology , data structure and ubiety between models, and etc , all of these are key points to be studied and resolved.This dissertation is concerned for these key points mentioned above, applying 3D modeling technology,3DGIS,interpolation techniques collision detection(AABB, OBB...)algorithms and computer graphics into the theory of gravity & magnetism forward and inversion , devised and realized 3D inversion interpretation system for gravitic & magnetic data. It can construct geology model flexibly and convinently, magnify , reduce ,ramble and rotate the models,draw beautiful model , besides, it have intuitionistic iterative result and unite auto inversion and man-machine mutual inversion. So, it give the physical prospector ,especially the gravity & magnetism interpreter,a convenient tool for explaining data. This dissertation 's study contents include following parts:1.Studing the interpretation strategy of the software, adopting man-machine mutual iterative algorithm and auto-inversion algorithm .2. Summarizing the method of constructing 3D geology model and applying suitable 3D data model to this system. The dissertation adopt following models ,(1) a series of regular shapes(sphere, ellipse sphere,sidestep,vertical cylinder, horizontal cylinder, titlted cylinder, cube,and etc). (2) a series of finite length arbitrary polygon colomn which is vertical and horizontal. (3) irregular TIN triangle surface .3. Discussting the overlap problem of model.it is forbidden that overlap or intersection occurring between models because it may result in repeated computation and wrong interpretation. The dissertation summarize some collision detection algorithms, and present a algorithm to avoid overlapping. There are not have this function among the 3D inversion interpretation systems for gravitic & magnetic data.Thus, it is a innovation point within this dissertation. 4. In order to give the physical interpreter a agile tool and a vivid result,the dissertation construct and edit model very flexibly ,and adopt various display scheme. And , studying the skills about geology objects and their vertexs under the environment of 3D and models ' topology modification stressly.5. Using above knowledge ,author programmed the 3D forward and inversion interpretation system for gravity and magnetism. It can explain a observational area's gravity and magnetism data by man-machine and auto inversion.it let the interpreter know the shape ,distribution,physical property of the mineral subsurface ,so provide intuitionistic data.The dissertation explain the restricts and shortcuts, and point out the improving direction further. For integrality, the dissertation explain some key technologies involved,such as: 3D model-constructing, marquardt algorithm, intersection test, and etc.It can be divided into 4 parts: the first part discusses the theory of 3D-modeling and visualization, applys it into gravity& magnetism field. Studing the suitable geology models for the system, and deducing the calculation formulation about these geology objects. The second part do demand analyse, and do general design according to the demand analyse. It is divided into modules and devised the data structure, key algorithms and techniques of alternation.The third part discuss how to realize and program the system according to the general design and give key codes accordingly that make reader easy to understand .The last part gives a idiographic applied example. |
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