检测地球的曲率 

显示地球的曲率如何影响其表面的路径.

定义一个路径，以艾弗尔铁塔为起点，依次沿测地线向4个指南针方位移动100公路.

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X start = Entity["Building", "TourEiffel"][ EntityProperty["Building", "Position"]]; d = Quantity[100, "Kilometers"]; path = {GeoDisplacement[{d, "North"}, "Geodesic"], GeoDisplacement[{d, "East"}, "Geodesic"], GeoDisplacement[{d, "South"}, "Geodesic"], GeoDisplacement[{d, "West"}, "Geodesic"]};

分段绘制四个路径图，并放大验证由于地球曲率路径都不闭合.

In[2]:=

X GraphicsRow[ Apply[GeoGraphics[{Red, PointSize[Large], Point[start], Darker[Green], Thickness[Large], GeoPath[{start, path}]}, ##1] &, {{}, {GeoCenter -> start, GeoRange -> Quantity[3, "Kilometers"]}}, {1}]]

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找出起点和终点间的距离.

In[3]:=

X GeoDistance[start, Last[GeoDestination[start, path]]]

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接下来取代测地线，跟随斜航线分段（恒定的恒向线的曲线）.

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X d = Quantity[100, "Kilometers"]; path = {GeoDisplacement[{d, "North"}, "Rhumb"], GeoDisplacement[{d, "East"}, "Rhumb"], GeoDisplacement[{d, "South"}, "Rhumb"], GeoDisplacement[{d, "West"}, "Rhumb"]};

终点的纬度与起点相同但经度并非如此.

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X GraphicsRow[ Apply[GeoGraphics[{Red, PointSize[Large], Point[start], Darker[Green], Thickness[Large], GeoPath[{start, path}]}, ##1] &, {{}, {GeoCenter -> start, GeoRange -> Quantity[3, "Kilometers"]}}, {1}]]

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找出起始点与终点间的距离.

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X GeoDistance[start, Last[GeoDestination[start, path]]]

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