Although you ll have an instructor , it s good for you to bear in mind the following points 指北针是在能见度不佳的情况下辩识方位的最佳工具。
2.
Magnetic minerals trapped inside ancient rocks have recorded hundreds of these so - called polarity reversals in the past 500 million years 在地磁反转后，指北针的指针会指向南极，而不再是冰冻的北极。
3.
Birds and compasses know north from south because , like a giant bar magnet , the earth ' s magnetic field has two poles that line up closely with the planet ' s axis of rotation 候鸟与指北针都知道何为北方、何为南方，因为地球就像一条巨型磁铁棒，它的磁场有两极，且这两个地磁的磁场线和地球的自转轴非常接近。
4.
Cartographic symbols , legend , scale - bar and other visual elements are used to design map . the map user will accurately translate the geographic information from the map , if appropriate symbols and other visual elements are selected to design map 地图整饰需要点、线、面符号和图例、比例尺、指北针等可视化要素，良好的可视化要素风格能使地图使用者迅速、准确的判读地理信息。
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The symbols used by one cartographer can be saved and moved between different pc , then different cartographers may use the same symbols to design map and get the same map result . how to quickly design a map is discussed finally 最后从实际工程需要出发，研究如何提高海量数据的制图效率，引入了模板库的概念，利用模板库保存符号、比例尺、图例、指北针等的风格样式，制图者通过模板库来共享劳动成果。
