| Airborne gamma detection technology is the aviation y spectrometer installed on the aircraft, then it measures over the area in accordance with pre-designed line and height detecting gamma rays emitted terrestrial media. The whole process is the completion of rocks and rock formations of natural radionuclides or ore grade for measuring geophysical-geochemical method. Airborne gamma ray spectrometry has been widely used in the field of mineral exploration due to its fast, convenient, efficient and economic characteristics. It also plays an important role in our nuclear resources exploration. However, airborne gamma ray spectrometry is easily influenced by the terrain, resulting in considerable distress in the latter part of the inversion, which isn’t very conducive to later work. Therefore, if there is a way to eliminate the interference of terrain airborne gamma ray spectrometry, it will greatly save manpower and resources to improve the efficiency of later work. In view of this, the main studies of this paper are:1). After I study aviation gamma spectrum measurement terrain correction problem, and master the classic theory of air gamma cone radiation field, I analysis in-depth of the domestic existing solutions to this problem, and find the imperfection of the existing methods. Some solutions are too simplified in terrain and difficult to be applied in practice. Some solutions are only aimed at 2D situation and can’t meet the actual need. Some solutions don’t consider three-dimensional situation comprehensively and their details are not perfect. Therefore, I demonstrate two basic calibration theories:integral algorithm and discrete algorithm by using mathematical derivation after I sum up the other people’ experience, make use of classic theory of aviation gamma cone radiation field and consider the complex three-dimensional terrain conditions. The integral algorithm theoretically gives the scope of geological body to solve topographic problem, and discrete algorithm is convenient for computer processing on the basis of integral algorithm. Additionally, I deduce formulas used for synchronization correction, and correction coefficient formulas used for topographic correction in future.2).Put forward the thought of terrain correction by using geographic information system and I develop a correction solution under Google Earth platform. This solution is got according to the characteristics of Google Earth platform combining with geography. In this process, firstly I deduce geographic coordinates formula according to sampling point for correction calculation, and I make good use of this formula to develop correction computation tools; Secondly, I deduce formula of calculating the geocentric Angle and distance for the correction, and by using the formula I develop correction calculation tools. Landmark sample point tools and correction computing tools are run well on Windows 7 platform. In software development, considering different elevation system in geographic coordinates, algorithm is designed to adapt to different vertical system.3). Because of the complexity of the actual terrain, certain correction is needed in discrete algorithm. Under the spherical coordinate, the route of the detector and landmarks sampling point may not be the air in the former period, and then a geological body. Maybe the air and geological body space for many times. In the presence of this kind of extremely complex, I revise discrete algorithm after considering computational efficiency and the characteristics of landmark sample point. I design the algorithm, analyze each possible situation, deduce the formula and develop the code used for correction calculation tool. |
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