毫无疑问,我们生活在三维世界中,但是当转动地球仪时,却发现我们所在的地域其实只用两条线——经度线和纬度线——就可以确定,而高度被忽略不计了。不过这并不意味着高度这一维不重要,对现代测量而言,高度是个不可或缺的要素。在现代工程中,比如修建管道和铁路,测量高低起伏的 There is no doubt that we live in the three-dimensional world, but when we turn the globe, we find that our region is actually only two lines - longitude and latitude - can be determined, and the height is ignored. However, this does not mean that height is not important, and height is an indispensable element for modern measurements. In modern engineering, such as building pipelines and railroads, measuring ups and downs