如何以设定的速度在2 gps点之间移动？

Question

I'm trying to create a function that will let me give 2 arguments, a new location and a speed to travel at (in meters / second)

It looks like this:

func (l *Location) Move(newLoc *Location, speed float64) {
    R := 6371.0 // Kilometers
    lat1 := l.Latitude * math.Pi / 180
    lat2 := l.Longitude * math.Pi / 180
    diffLat := (newLoc.Latitude - l.Latitude) * math.Pi / 180
    diffLon := (newLoc.Longitude - l.Longitude) * math.Pi / 180

    a := math.Sin(diffLat/2)*math.Sin(diffLat/2) +
        math.Cos(lat1)*math.Cos(lat2)*math.Sin(diffLon/2)*math.Sin(diffLon/2)
    c := 2 * math.Atan2(math.Sqrt(a), math.Sqrt(1-a))

    distanceToMove := R * c // Distance to travel in a straight line, in Kilometers


}

The only thing I'm having trouble with is thinking of the formula to make the latitude, start at its current position, and end up at its new position over a set amount of time.

So say the person changed the latitude from 56.65 to 58.12 and I told it to travel at 1.3m/s how can I accomplish this. Thanks.

Answer 1

If I understand your question, your goal is to compute all the intermediate points between two location, starting from one location and going to the second one using a specified speed.

If I'm correct, the following is how I would get a first solution. If anyone can improve this, I'd appreciate.

On the proj4 documentation, you can find a lot of information on how to compute distance between two points.

Starting from points A to reach B with a given speed (m/s), just means to compute each seconds a point A' that is at a distance m from A on the line AB.

In a more algorithmic way (based on Vincenty's formula):

func (l *Location) Move(newLoc *Location, speed float64) Location {
    azimuthA, azimuthB, d := inverseVincenty(l, newLoc)

    // Use the direct vincenty's formula.
    // Here transform speed to get the correct value
    // without transformation, since speed is in m/s,
    // the resulting point will be at speed(m) distance from l.
    res := directVincenty(l, speed, azimuthA)

    // Now res shall contain your new point.
    return res
}

func main() {
    // init A and B and speed values.
    C := A // to conserve A position.
    t := time.Tick(1* time.Second)
    for stop := false; !stop; {
        select {
            case <- t:
            C = C.Move(B, speed)
            case // here a break condition:
                stop = true
        }
    }
}

I think thats a start, any comment is appreciate on this answer.