1·Maybe they sense slight variations in the rate of change in the magnetic field, much like a hiker reads tightly spaced lines on a topographic map to discern a distinctive canyon.
也许它们感受磁场变化速度的细微变化，就像登山旅行者参照地形图上密密麻麻的线段以辨别一个与众不同的峡谷。
2·So, a topographic map, this one from the US geological survey shows you, basically, all the level curves of an altitude function on a piece of land.
这是一幅由美国地形勘测出来的地形图，基本上，所有海拔等高线在一块陆地上。
3·The 3d images from LRO orbital photography are being used to make an exact digital topographic map of the moon, and this is fact may tweak the mean elevation value.
LRO轨道摄影机拍摄的3d图像被用作制作月球精确数字地形图，而这可能会调整平均高度值。
4·Traditional construction methods firstly in the small scale topographic map, choose several feasible options, through field reconnaissance to confirm the optimize region.
传统的机场建设方法是首先在小比例尺地形图上选择几种可行方案，通过实地踏勘确定最佳区域。
5·C or F value, the X and Y coordinates of the center of a pixel at the up-left corner of the image, can be measured according to characteristic point in topographic map.
值为栅格图像左上角像素中心在地图上的X，Y坐标，其值可以根据特征点在地形图中的坐标量测获得。