从轴承和距离计算纬度和长度 [英] calculating Lat and Long from Bearing and Distance

问题描述

我很难将头部缠绕在一些三角函数上。我试图从起始纬度和对数以及距离和方位推导出目的地纬度和经度。

I'm having a hard time wrapping my head around some Trigonometry. I am trying to deduce a destination latitude and longitude from a start lat and log and distance and bearing.

幸运的是，我发现了一个令人惊叹的网站，它描述了我需要的功能：
http://www.movable-type.co.uk/ scripts / latlong.html 目的地点给定距离并从起点开始承载
我在我的java程序中尝试过它，但它对我不起作用。我按照网站的说法部署了它。这是我的代码：

Fortunately, I found an amazing site which describes exactly the function I need: http://www.movable-type.co.uk/scripts/latlong.html " Destination point given distance and bearing from start point " I tried it in my java program but it is not working for me. I deployed it as the website said. Here is my code:

double dist = 150/6371;
double brng = Math.toRadians(90);
double lat1 = Math.toRadians(26.88288045572338);
double lon1 = Math.toRadians(75.78369140625);

double lat2 = Math.asin( Math.sin(lat1)*Math.cos(dist) + Math.cos(lat1)*Math.sin(dist)*Math.cos(brng) );
double a = Math.atan2(Math.sin(brng)*Math.sin(dist)*Math.cos(lat1), Math.cos(dist)-Math.sin(lat1)*Math.sin(lat2));
System.out.println("a = " +  a);
double lon2 = lon1 + a;

lon2 = (lon2+ 3*Math.PI) % (2*Math.PI) - Math.PI;

System.out.println("Latitude = "+Math.toDegrees(lat2)+"\nLongitude = "+Math.toDegrees(lon2));

但它显示输出为：

a = 0.0
Latitude = 26.882880455723377
Longitude = 75.78369140625

我没有得到我在做错的地方。请任何人帮我解决问题。

I am not getting where i am doing the mistake. Please anybody can help me to find out the problem.

提前使用Thanx。 ： - ）

Thanx in Advance. :-)

推荐答案

你的问题就在你的第一行。

Your problem is on your first line.

尝试

double dist = 150.0 / 6371.0;

原因是 150/6371 获取计算为 0 ，因为它执行整数除法（而不是浮点除法）。即使结果存储在 double 中也是如此。您可以通过使两个数字中的一个成为浮点字面值来强制浮点除法。

The reason is that 150/6371 gets calculated as 0, because it performs integer division (rather than floating point division). This is true even though the result is being stored in a double. You can force floating point division by making one of the two numbers a floating point literal.

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