如何计算当前方向与GPS点之间的角度

Question

我有 2 个点（Android Location 对象）：当前位置和目标位置。我还有设备的方向（以度为单位）。

我想计算目标位置和方向之间的角度。怎样做才正确呢？

我从 FusedLocationProvider 接收位置（如果有的话）。现在我只用

float requiredAngle = Math.abs(location.getBearing() - 180 - target.bearingTo(location));

float angleBetween = Math.abs(requiredAngle - location.getBearing()); 它返回的角度不正确。

我想我应该计算真北和磁北之间的差异并添加设备方向。然后使用 currentPosition.bearingTo(target)，并从方位中减去设备方向。

Answer 1

这个角度称为相对方位角。

将侦听器注册到 Sensor.TYPE_ROTATION_VECTOR、Sensor.TYPE_ACCELEROMETER、Sensor.TYPE_MAGNETIC_FIELD。喜欢：

sensorManager.registerListener(listener, sensorManager.getDefaultSensor(Sensor.TYPE_ROTATION_VECTOR), SensorManager.SENSOR_DELAY_NORMAL);

然后为此创建一个监听器：

private float[] gravity;
private float[] geomagnetic;
private float[] R = new float[9];
private float[] I = new float[9];    

@Override
public void onSensorChanged(SensorEvent event) {
    if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER) {
        gravity = sensor.values(); // Just save the values
    }

    if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD) {
        geomagnetic = sensor.values();
    }

    if (SensorManager.getRotationMatrix(R, I, gravity, geomagnetic)) { // If something is wrong (like device is in free fall)
        float orientation[] = new float[3];
        SensorManager.getOrientation(R, orientation);
        // Now you have values from -PI to PI
        float heading;
        if (R[0] > 0) { // R[0] is heading
            heading = R[0] * 180 / PI;
        } else { // -PI, eq. from South to West to North
            heading = (Math.abs(R[0]) * 180 / PI) * 2;
        }

        float relativeBearing = location.bearingTo(target) - heading;
        if (relativeBearing < 0) {
            relativeBearing = 360 + relativeBearing;
        }
    }
}

文档： https://developer.android.com/reference/android/hardware/SensorManager#getRotationMatrix(float[],%20float[],%20float[],%20float[]) https://developer.android.com /reference/android/hardware/SensorManager#getOrientation(float[],%20float[])