android - 我怎样才能沿着道路推断得更远？

Question

给定移动设备在短时间内的实时位置数据，我如何才能沿着这条路获得更远的纬度/经度对，比如 2 英里，甚至更好，5 分钟的车程？

我看到我可以使用 Google 的 Roads API 捕捉到给定纬度/经度对的道路 https://developers.google.com/maps/documentation/roads/snap ，但这只会让我走到那一步。

这将在 Android 应用中。

Answer 1

给定一条表示为 List<LatLng> 的路线, 此函数计算路线上的点 distance距离 origin 米在该路线上(使用 Google Maps API Utility Library 进行一些计算):

private LatLng extrapolate(List<LatLng> path, LatLng origin, float distance) {
    LatLng extrapolated = null;

    if (!PolyUtil.isLocationOnPath(origin, path, false, 1)) { // If the location is not on path non geodesic, 1 meter tolerance
        return null;
    }

    float accDistance = 0f;
    boolean foundStart = false;
    List<LatLng> segment = new ArrayList<>();

    for (int i = 0; i < path.size() - 1; i++) {
        LatLng segmentStart = path.get(i);
        LatLng segmentEnd = path.get(i + 1);

        segment.clear();
        segment.add(segmentStart);
        segment.add(segmentEnd);

        double currentDistance = 0d;

        if (!foundStart) {
            if (PolyUtil.isLocationOnPath(origin, segment, false, 1)) {
                foundStart = true;

                currentDistance = SphericalUtil.computeDistanceBetween(origin, segmentEnd);

                if (currentDistance > distance) {
                    double heading = SphericalUtil.computeHeading(origin, segmentEnd);
                    extrapolated = SphericalUtil.computeOffset(origin, distance - accDistance, heading);
                    break;
                }
            }
        } else {
            currentDistance = SphericalUtil.computeDistanceBetween(segmentStart, segmentEnd);

            if (currentDistance + accDistance > distance) {
                double heading = SphericalUtil.computeHeading(segmentStart, segmentEnd);
                extrapolated = SphericalUtil.computeOffset(segmentStart, distance - accDistance, heading);
                break;
            }
        }

        accDistance += currentDistance;
    }

    return extrapolated;
}

这里有一些测试:

List<LatLng> route = new ArrayList<>();
route.add(new LatLng(40, 4));
route.add(new LatLng(40.1, 4));
route.add(new LatLng(40.1, 4.1));
route.add(new LatLng(40.2, 4.1));
route.add(new LatLng(40.2, 4.2));
route.add(new LatLng(40.3, 4.2));
route.add(new LatLng(40.3, 4.3));

LatLng origin;
LatLng extrapolated;

origin = new LatLng(40.1, 4.05);
extrapolated = extrapolate(route, origin, 30000);
Log.e("Extrapolated1", "" + extrapolated); //  lat/lng: (40.25517043951189,4.2)

origin = new LatLng(40.05, 4);
extrapolated = extrapolate(route, origin, 100);
Log.e("Extrapolated2", "" + extrapolated); //  lat/lng: (40.05089932033549,4.0)

origin = new LatLng(40.05, 4);
extrapolated = extrapolate(route, origin, 50000);
Log.e("Extrapolated3", "" + extrapolated); //  lat/lng: (40.300010207449226,4.261348349980259)

origin = new LatLng(40.05, 4);
extrapolated = extrapolate(route, origin, 100000);
Log.e("Extrapolated4", "" + extrapolated); //  null (result out of the route)