Collections.sort(list, (o1, o2) -> (int) (o1.x - o2.x));
List<Point> line = new ArrayList<>();
for (Point point : list) {
    if (line.size() == 0) {
        line.add(point);
        continue;
    }
    Point compare = line.get(line.size() - 1);
    double distance = Math.sqrt(Math.pow(point.y - compare.y, 2) + Math.pow(point.x - compare.x, 2));
    if (distance > step) {
        line.add(point);
    }
}
if (null != result) {
    for (Point point : line) {
        Imgproc.drawMarker(result, point, new Scalar(0, 0, 255));
    }
}