百度地图坐标解密方法精度分析

介绍了3种百度坐标解密的方法——等量偏移法、格网法和BP神经网络,并改进了等量偏移法,得到了二阶差分公式。选取乌鲁木齐、拉萨、兰州、北京、上海和三沙6座城市,在各城市中心点建立0.1°方格的研究区域,对比了上述解密方法得到的WGS-84预测值与参考值的经纬度差离散图和点位误差分布频率表。结果表明,等量偏移二阶差分法的坐标解密精度在10 m左右,等量偏移一阶差分法在20 m左右,BP神经网络在50 m左右,格网法在100 m左右。同时,利用百度地图提供的距离和面积量算工具对等量偏移一阶差分和二阶差分方法进行了应用验证。

Application of the equivalent offset migration method in acoustic log reflection imaging

Borehole acoustic reflection logging can provide high resolution images of nearborehole geological structure. However, the conventional seismic migration and imaging methods are not effective because the reflected waves are interfered with the dominant borehole-guided modes and there are only eight receiving channels per shot available for stacking. In this paper, we apply an equivalent offset migration method based on wave scattering theory to process the acoustic reflection imaging log data from both numerical modeling and recorded field data. The result shows that, compared with the routine post-stack depth migration method, the equivalent offset migration method results in higher stack fold and is more effective for near-borehole structural imaging with low SNR acoustic reflection log data.

一种百度地图坐标高精度解密方法

为解决百度地图在实际应用中坐标偏移的问题,提出了一种百度地图坐标高精度解密方法——等量偏移迭代逼近(equivalent offset iterative approximation,EOIA)法。选用中国大陆范围内的随机坐标点,分析了EOIA法坐标解密的点位误差、距离误差和效率。结果表明,EOIA法在百度地图坐标解密中的点位误差能达到厘米级,距离相对误差在10^(-7)量级,且该方法适用范围广、效率高、易操作。