为增加的高度计算纬度和经度

Question

我想在Android谷歌地图上绘制一条折线图。我有路径的GPS坐标，希望能够在地图上显示汽车速度，并且通过线的高度显示出来。

参考这张图片，

每个GPS（纬度、经度）点需要加上一些高度，并计算相应的GPS（纬度、经度）点。我想在3D视图中显示这个效果，因此在摄像机位置发生变化时必须更改这些点，但首先要计算添加高度后的GPS点。

例如：

ArrayList<LatLng> basePoints = new ArrayList<LatLng>();
basePoints.add(new LatLng(53.262688, -2.500792));
basePoints.add(new LatLng(53.262758, -2.500897));
basePoints.add(new LatLng(53.262789, -2.501087));
basePoints.add(new LatLng(53.262798, -2.501229));
basePoints.add(new LatLng(53.262785, -2.501414));
basePoints.add(new LatLng(53.262760, -2.501594));
basePoints.add(new LatLng(53.262707, -2.501811));
basePoints.add(new LatLng(53.262655, -2.501943));

ArrayList<LatLng> topPoints = new ArrayList<LatLng>();
topPoints.add(new LatLng(53.262939, -2.500779));
topPoints.add(new LatLng(53.262975, -2.500916));
topPoints.add(new LatLng(53.262914, -2.501098));
topPoints.add(new LatLng(53.263055, -2.501248));
topPoints.add(new LatLng(53.262925, -2.501439));
topPoints.add(new LatLng(53.263045, -2.501581));
topPoints.add(new LatLng(53.262907, -2.501844));
topPoints.add(new LatLng(53.263002, -2.502015));

任何想法如何做到这一点？ 谢谢

- AL̲̳I

Answer 1

根据您提供的链接，我已经为您实现了这个功能。

final ArrayList<LatLng> basePoints = new ArrayList<LatLng>();
basePoints.add(new LatLng(53.262688, -2.500792));
basePoints.add(new LatLng(53.262758, -2.500897));
basePoints.add(new LatLng(53.262789, -2.501087));
basePoints.add(new LatLng(53.262798, -2.501229));
basePoints.add(new LatLng(53.262785, -2.501414));
basePoints.add(new LatLng(53.262760, -2.501594));
basePoints.add(new LatLng(53.262707, -2.501811));
basePoints.add(new LatLng(53.262655, -2.501943));

final ArrayList<Double> speedPoints = new ArrayList<Double>();
speedPoints.add(7.955734692);
speedPoints.add(8.761378798);
speedPoints.add(11.07760474);
speedPoints.add(13.69594751);
speedPoints.add(15.50864695);
speedPoints.add(16.01217576);
speedPoints.add(15.60935179);
speedPoints.add(15.71005663);

LatLngBounds.Builder bounds = new LatLngBounds.Builder();
for(int i=0;i<basePoints.size();i++)
{
    bounds.include(basePoints.get(i));
}
map.moveCamera(CameraUpdateFactory.newLatLngBounds(bounds.build(), 300,300,0));
map.setOnCameraChangeListener(new OnCameraChangeListener() {
    @Override
    public void onCameraChange(CameraPosition arg0)
    {
        map.clear();
        ArrayList<LatLng> topPoints = new ArrayList<LatLng>();
        for(int i=0;i<basePoints.size();i++)
        {
            topPoints.add(moveByDistance(basePoints.get(i), speedPoints.get(i)*3,map.getCameraPosition().bearing));
        }
        PolylineOptions topPO = new PolylineOptions();
        topPO.addAll(topPoints).width(5).color(Color.BLUE).geodesic(true);
        map.addPolyline(topPO);
        for(int i=0;i<basePoints.size()-1;i++)
        {
            map.addPolygon(new PolygonOptions().add(basePoints.get(i),topPoints.get(i),topPoints.get(i+1),basePoints.get(i+1),basePoints.get(i)).fillColor(Color.YELLOW).strokeColor(Color.YELLOW));
        }
    }

});

/**
 * Move a LatLng-Point into a given distance and a given angle (0-360,
 * 0=North).
 */
public static LatLng moveByDistance(LatLng startGp, double distance,double angle) {
    /*
     * Calculate the part going to north and the part going to east.
     */
    double arc = Math.toRadians(angle);
    double toNorth = distance * Math.cos(arc);
    double toEast = distance * Math.sin(arc);
    double lonDiff = meterToLongitude(toEast, startGp.latitude);
    double latDiff = meterToLatitude(toNorth);
    return new LatLng(startGp.latitude + latDiff, startGp.longitude + lonDiff);
}

private static double meterToLongitude(double meterToEast, double latitude) {
    double latArc = Math.toRadians(latitude);
    double radius = Math.cos(latArc) * EARTHRADIUS;
    double rad = meterToEast / radius;
    double degrees = Math.toDegrees(rad);
    return degrees;
}

private static double meterToLatitude(double meterToNorth) {
    double rad = meterToNorth / EARTHRADIUS;
    double degrees = Math.toDegrees(rad);
    return degrees;
}

我希望这将有助于您实现这一点。

- Ana

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这正是我想做的，我没想到会这么容易。CameraChangeListener 很容易实现。谢谢 :) - AL̲̳I

Answer 2

计算一米等于多少度：

在赤道：

360度， 周长为40,000,000米。

因此，一米约为

double static final METERS_PER_DEGREE = 360.0 / 40 000 000;

现在将纬度偏移，例如3米：

lat = lat + 3 * METERS_PER_DEGREE.

当移动经度时，必须乘以 cos(Math.toRadians(latitude);。

double oneMeterLongitudeInDegrees = METERS_PER_DEGREE * cos(Math.toRadians(latitude);

lonNew = lonOld + 3 * oneMeterLongitudeInDegrees 

- AlexWien

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谢谢，我正在查看这个答案，它似乎运行良好。 - AL̲̳I