问题
I have a little problem... Does anyone knows about how can i implement this?
I need a method in java like this:
public /*COORDINATE OBJECT*/ getTrilaterationPointBetween(
/*COORDINATE OBJECT*/ coordinate1, double distance1,
/*COORDINATE OBJECT*/ coordinate2, double distance2,
/*COORDINATE OBJECT*/ coordinate3, double distance3){
//MAGIC
return /*COORDINATE OBJECT*/;
}
In practice this method will receive 3 coordinates and the distance between "myLocation" with one of them...
I need the algorithm of the Trilateration!!
I did some searches and made some tests and the results are driving me into the middle of the pacific!!
About the OBJECT, is really simple, have 2 variables representing Latitude and Longitude.
I have tried this method:
static double[] MyTrilateration(Ponto ponto1, double dist1,
Ponto ponto2, double dist2,
Ponto ponto3, double dist3) {
double[] tmpWAP1 = new double[3];
double[] tmpWAP2 = new double[3];
double[] tmpWAP3 = new double[3];
double tmpLat2, tmpLong2, tmpLat3, tmpLong3;
double tmpSlide, deg;
double MyLat, MyLong;
double[] MyLocation = new double[2];
tmpLat2 = ponto2.getX() - ponto1.getX();
tmpLong2 = ponto2.getY() - ponto1.getY();
tmpLat3 = ponto3.getX() - ponto1.getX();
tmpLong3 = ponto3.getY() - ponto1.getY();
tmpSlide = Math.sqrt(Math.pow(tmpLat2,2)+Math.pow(tmpLong2,2));
deg = (180/Math.PI)*Math.acos( Math.abs(tmpLat2)/Math.abs(tmpSlide));
if( (tmpLat2>0 && tmpLong2>0) ) {
deg = 360 - deg;
}
else if( (tmpLat2<0 && tmpLong2>0) ) {
deg = 180 + deg;
}
else if( (tmpLat2<0 && tmpLong2<0)){
deg = 180 - deg;
}
else if( (tmpLat2>0 && tmpLong2<0)) {
deg = deg;
}
tmpWAP1[0] = 0.0;
tmpWAP1[1] = 0.0;
tmpWAP1[2] = dist1;
tmpWAP2 = myRotation(tmpLat2, tmpLong2, dist2, deg);
tmpWAP3 = myRotation(tmpLat3, tmpLong3, dist3, deg);
MyLat = (Math.pow(tmpWAP1[2],2)-Math.pow(tmpWAP2[2],2)+Math.pow(tmpWAP2[0],2))/(2*tmpWAP2[0]);
MyLong = (Math.pow(tmpWAP1[2],2)-Math.pow(tmpWAP3[2],2)-Math.pow(MyLat,2)
+Math.pow(MyLat-tmpWAP3[0],2)+Math.pow(tmpWAP3[1], 2))/(2*tmpWAP3[1]);
MyLocation = myRotation(MyLat, MyLong, 0, -deg);
MyLocation[0] = MyLocation[0] + ponto1.getX();
MyLocation[1] = MyLocation[1] + ponto1.getY();
return MyLocation;
}
and this method:
public String getCoordinateWith(
Ponto a, Ponto b, Ponto c,
Float dA,
Float dB,
Float dC) {
Float W, Z, x, y, y2;
W = dA*dA - dB*dB - a.getX()*a.getX() - a.getY()*a.getY() + b.getX()*b.getX() + b.getY()*b.getY();
Z = dB*dB - dC*dC - b.getX()*b.getX() - b.getY()*b.getY() + c.getX()*c.getX() + c.getY()*c.getY();
x = (W*(c.getY()-b.getY()) - Z*(b.getY()-a.getY())) / (2 * ((b.getX()-a.getX())*(c.getY()-b.getY()) - (c.getX()-b.getX())*(b.getY()-a.getY())));
y = (W - 2*x*(b.getX()-a.getX())) / (2*(b.getY()-a.getY()));
//y2 is a second measure of y to mitigate errors
y2 = (Z - 2*x*(c.getX()-b.getX())) / (2*(c.getY()-b.getY()));
y = (y + y2) / 2;
return "Position: " + x + " , " + y;
}
Thank you!
回答1:
I got it! That'is my method, works for me, is not 100% accurate! Works with z = 0 and only with 3 different points(2D coordinates).
The class "Ponto" is a simple class with two values (X and Y/Lat and Lon), "double".
public static Ponto getLocationByTrilateration(
Ponto ponto1, double distance1,
Ponto ponto2, double distance2,
Ponto ponto3, double distance3){
//DECLARACAO DE VARIAVEIS
Ponto retorno = new Ponto();
double[] P1 = new double[2];
double[] P2 = new double[2];
double[] P3 = new double[2];
double[] ex = new double[2];
double[] ey = new double[2];
double[] p3p1 = new double[2];
double jval = 0;
double temp = 0;
double ival = 0;
double p3p1i = 0;
double triptx;
double xval;
double yval;
double t1;
double t2;
double t3;
double t;
double exx;
double d;
double eyy;
//TRANSFORMA OS PONTOS EM VETORES
//PONTO 1
P1[0] = ponto1.getX();
P1[1] = ponto1.getY();
//PONTO 2
P2[0] = ponto2.getX();
P2[1] = ponto2.getY();
//PONTO 3
P3[0] = ponto3.getX();
P3[1] = ponto3.getY();
//TRANSFORMA O VALOR DE METROS PARA A UNIDADE DO MAPA
//DISTANCIA ENTRE O PONTO 1 E A MINHA LOCALIZACAO
distance1 = (distance1 / 100000);
//DISTANCIA ENTRE O PONTO 2 E A MINHA LOCALIZACAO
distance2 = (distance2 / 100000);
//DISTANCIA ENTRE O PONTO 3 E A MINHA LOCALIZACAO
distance3 = (distance3 / 100000);
for (int i = 0; i < P1.length; i++) {
t1 = P2[i];
t2 = P1[i];
t = t1 - t2;
temp += (t*t);
}
d = Math.sqrt(temp);
for (int i = 0; i < P1.length; i++) {
t1 = P2[i];
t2 = P1[i];
exx = (t1 - t2)/(Math.sqrt(temp));
ex[i] = exx;
}
for (int i = 0; i < P3.length; i++) {
t1 = P3[i];
t2 = P1[i];
t3 = t1 - t2;
p3p1[i] = t3;
}
for (int i = 0; i < ex.length; i++) {
t1 = ex[i];
t2 = p3p1[i];
ival += (t1*t2);
}
for (int i = 0; i < P3.length; i++) {
t1 = P3[i];
t2 = P1[i];
t3 = ex[i] * ival;
t = t1 - t2 -t3;
p3p1i += (t*t);
}
for (int i = 0; i < P3.length; i++) {
t1 = P3[i];
t2 = P1[i];
t3 = ex[i] * ival;
eyy = (t1 - t2 - t3)/Math.sqrt(p3p1i);
ey[i] = eyy;
}
for (int i = 0; i < ey.length; i++) {
t1 = ey[i];
t2 = p3p1[i];
jval += (t1*t2);
}
xval = (Math.pow(distance1, 2) - Math.pow(distance2, 2) + Math.pow(d, 2))/(2*d);
yval = ((Math.pow(distance1, 2) - Math.pow(distance3, 2) + Math.pow(ival, 2) + Math.pow(jval, 2))/(2*jval)) - ((ival/jval)*xval);
t1 = ponto1.getX();
t2 = ex[0] * xval;
t3 = ey[0] * yval;
triptx = t1 + t2 + t3;
retorno.setX(triptx);
t1 = ponto1.getY();
t2 = ex[1] * xval;
t3 = ey[1] * yval;
triptx = t1 + t2 + t3;
retorno.setY(triptx);
return retorno;
}
来源：https://stackoverflow.com/questions/24761658/trilateration-method-android-java