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Thread: converging point clouds

  1. #1
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    Default converging point clouds

    i dont know if anyone uses processing here, but im writing some code for simplifying point clouds

    i have written code that makes a random point cloud, and the second part of the code finds the points that are close to each other in a certain tolerance, and deletes them, leaving one point in the center of the deleted group. i cant seem to get the second part of the code to work.
    first part of code :


    void setup() {

    size (400, 400);
    background(255);

    int xnum = 1000;
    int ynum = 1000;
    int[] xarray = new int[xnum];
    int[] yarray = new int[ynum];
    // create random numbers

    for (int i = 0; i < xnum; i++) {
    for (int j = 0; j < xnum; j++) {
    xarray[i] = int(random(0, 400));
    yarray[j] = int(random(0, 400));
    }
    }
    //create points
    for (int i = 0; i < xnum; i++) {
    for (int j = 0; j < xnum; j++) {
    point(xarray[i], yarray[i]);
    }
    }
    }



    Converge(ArrayList<PVector> pts, double tol)
    {
    PVector[] deltaPos = new PVector[pts.length];
    boolean check = false;
    tol = tol * tol;
    for (int i = 0; i < pts.length; i++)
    {
    deltaPos[i] = PVector.sub(LocalCentroid(pts[i], pts, tol), pts[i]);
    if (deltaPos[i].x + deltaPos[i].y > ModelAbsoluteTolerance) // ModelAbsoluteTolerance: to be defined!
    {
    check = true;
    }
    }
    for (int i = 0; i < pts.length; i++)
    {
    pts[i].add(deltaPos[i]);
    }
    return check;
    }

    LocalCentroid(PVector p, ArrayList<PVector> pts, double tolSqr)
    {
    PVector cntr = new PVector(0, 0);
    int count = 0;
    for (int i = 0; i < pts.length; i++)
    {
    PVector testVec = PVector.sub(pts[i], p);
    double lsqr = testVec.x * testVec.x + testVec.y * testVec.y;
    if (lsqr < tolSqr)
    {
    cntr.add(pts[i]);
    count += 1;
    }
    }
    return PVector.div(cntr, count);
    }


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: converging point clouds

    i cant seem to get the second part of the code to work.
    This sounds like a logic problem. Your code probably doesn't follow your algorithm correctly.
    If you know how your algorithm works, you should be able to look at the printed output from printlns of the variables in your code and see where the code is going wrong.
    Add lots of printlns to your code to show how the variables' values are changing. The printout should show you where your code is wrong.

    Since your code does not contain any comments on what its logic is and how it is implementing the algorithm, not many people will be able to help you.

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