在没有目的地的Google地图上x公里后获取纬度经度？

问题描述

我正在创建一个 Android 应用程序，该应用程序需要在X公里以后找到同一路线上的坐标。 我有两个坐标 x1，y1 & x2，y2 在路上。现在，我的要求是在大约3公里后找到坐标 x3，y3 （即，在 x2，y2 之后的坐标不是之间 x1，y1 & x2，y2 ）。
$如果您知道。

这是基于。

如果你想在同一条路上的点，您可以结算。

I am creating an Android app which requires finding a coordinate on the same route after X kilometers.

I have two coordinates x1,y1 & x2,y2 on a road. Now, my requirement is to find coordinate x3,y3 after some 3 kilometers (i.e., coordinate after x2,y2 not between x1,y1 & x2,y2) on the same road.

How can this be achieved ?

解决方案

If you know the bearing, you can calculate the destination coordinate.

Sample Code:

private LatLng getDestinationPoint(LatLng source, double brng, double dist) {
        dist = dist / 6371;
        brng = Math.toRadians(brng);

        double lat1 = Math.toRadians(source.latitude), lon1 = Math.toRadians(source.longitude);
        double lat2 = Math.asin(Math.sin(lat1) * Math.cos(dist) +
                                Math.cos(lat1) * Math.sin(dist) * Math.cos(brng));
        double lon2 = lon1 + Math.atan2(Math.sin(brng) * Math.sin(dist) *
                                        Math.cos(lat1),
                                        Math.cos(dist) - Math.sin(lat1) *
                                        Math.sin(lat2));
        if (Double.isNaN(lat2) || Double.isNaN(lon2)) {
            return null;
        }
        return new LatLng(Math.toDegrees(lat2), Math.toDegrees(lon2));
    }

Sample usage:

   double radiusInKM = 10.0;
   double bearing = 90;
   LatLng destinationPoint = getDestinationPoint(new LatLng((25.48, -71.26), bearing, radiusInKM);

Or you can use heading between your pointA and pointB instead of bearing:

LatLng destinationPoint = getDestinationPoint(new LatLng(37.4038194,-122.081267), SphericalUtil.computeHeading(new LatLng(37.7577,-122.4376), new LatLng(37.4038194,-122.081267)), radiusInKM);

The SphericalUtil.computeHeading(p1, p2); method is from the Android Google Maps Utility library.

This is based on the Javascript method from this Stackoverflow answer.

If you want the point on same road, you might checkout this PHP answer.

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