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标题: 地理空间-Java实现航迹稀释 [打印本页]

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作者: 吴旭华    时间: 2024-11-11 10:41
标题: 地理空间-Java实现航迹稀释
Java实现航迹点稀释算法（Douglas - Peucker算法）的示例代码，该算法可在保证航迹团体外形变化不大的情况下减少航迹点数量：

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import java.util.ArrayList;
import java.util.List;
 
class Point {
    double x;
    double y;
 
    public Point(double x, double y) {
        this.x = x;
        this.y = y;
    }
}
 
public class TrackThinning {
 
    public static List<oint> douglasPeucker(List<oint> points, double epsilon) {
        if (points.size() < 3) {
            return points;
        }
 
        int index = -1;
        double dmax = 0;
        int end = points.size();
        for (int i = 1; i < end - 1; i++) {
            double d = perpendicularDistance(points.get(i), points.get(0), points.get(end - 1));
            if (d > dmax) {
                index = i;
                dmax = d;
            }
        }
 
        List<oint> result = new ArrayList<>();
        if (dmax > epsilon) {
            List<oint> recursiveResult1 = douglasPeucker(points.subList(0, index + 1), epsilon);
            List<oint> recursiveResult2 = douglasPeucker(points.subList(index, points.size()), epsilon);
 
            result.addAll(recursiveResult1.subList(0, recursiveResult1.size() - 1));
            result.addAll(recursiveResult2);
        } else {
            result.add(points.get(0));
            result.add(points.get(points.size() - 1));
        }
 
        return result;
    }
 
    private static double perpendicularDistance(Point point, Point start, Point end) {
        double dx = end.x - start.x;
        double dy = end.y - start.y;
        double numerator = Math.abs((dy * point.x - dx * point.y) + (end.x * start.y - end.y * start.x));
        double denominator = Math.sqrt(dy * dy + dx * dx);
        return numerator / denominator;
    }
 
    public static void main(String[] args) {
        List<oint> points = new ArrayList<>();
        points.add(new Point(0, 0));
        points.add(new Point(1, 1));
        points.add(new Point(2, 2));
        points.add(new Point(3, 2));
        points.add(new Point(4, 3));
        points.add(new Point(5, 4));
 
        double epsilon = 0.5;
        List<oint> thinnedPoints = douglasPeucker(points, epsilon);
 
        for (Point p : thinnedPoints) {
            System.out.println("(" + p.x + ", " + p.y + ")");
        }
    }
}
 
 

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