Trilateration Method Android Java

Question

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*/ getTrila         


        

Answer 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;
    }