Vincenty Direct公式纬度问题 [英] Vincenty Direct formula Latitude issue

问题描述

我正在使用Mike Gavaghan的Geodesy库进行计算:

I'm using Mike Gavaghan's Geodesy library to calculate:

新的谷歌纵横从起始位置，方位角和距离开始的经度(Vincenty直接公式，CalculateEndingGlobalCoordinates)

但是，我看到了一些意想不到的结果.

However, I am seeing some results I did not expect.

在使用Direct公式时，计算新点Due East(90度)时，我希望纬度不会改变，但是以下代码返回了意外的结果:

When using the Direct formula, calculating a new point Due East (90 degrees), I expected the Latitude to NOT change, However the following code returns unexpected results:

GeodeticCalculator geoCalc = new GeodeticCalculator();
        Ellipsoid reference = Ellipsoid.WGS84;
        Angle startBearing = new Angle(90);
        double metersDistance = 50000;

        GlobalCoordinates dest = geoCalc.CalculateEndingGlobalCoordinates(
            reference, 
            new GlobalCoordinates(
                new Angle(50.0d), 
                new Angle(0.0d)
                ), 
            startBearing, 
            metersDistance
           );

我希望纬度(50.0)保持不变，但返回"49.7909857". 这可能是正确的，但据我所知，无论纬度如何，如果您向东行驶，都应该保持相同的纬度?

I expected the Latitude (50.0) to remain the same, but it returns "49.7909857". This may well be correct, but to my knowledge, regardless of Latitude, if you travel due east, you should remain on the same Latitude?

在纬度为0.0时，纬度确实保持不变.

At a latitude of 0.0, the Latitude does indeed remain the same.

这是库中的错误，还是我缺乏理解?

Is this a bug in the Library, or a lack of understanding on my part?

推荐答案

应该改变纬度！ 90度只是您的 initial 方位.为了保持直线路径(测地线的定义)，该路径必须弯曲远离纬度圆(除非它是赤道).为了帮助理解这一点，请想象一个接近90°的纬度.这是一个围绕北极的半径为1m的圆.

The latitude is supposed to change! 90° is just your initial bearing. In order to maintain a straight path (the definition of a geodesic), the path must bend away from the circle of latitude (unless it's the equator). To help understand this, imagine a latitude so close to 90° that it's a circle of radius 1m about the north pole.

这篇关于Vincenty Direct公式纬度问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！