摘要：最小外接矩形外接矩形計(jì)算對(duì)一個(gè)凸多邊形進(jìn)行外接矩形計(jì)算，需要知道當(dāng)前面的最大和最小值，即可獲得外接矩形最小外接矩形計(jì)算對(duì)凸多邊形的每一條邊都繪制一個(gè)外接矩形求最小面積。

對(duì)一個(gè)凸多邊形進(jìn)行外接矩形計(jì)算，需要知道當(dāng)前面的最大xy 和最小xy值，即可獲得外接矩形

對(duì)凸多邊形的每一條邊都繪制一個(gè)外接矩形求最小面積。下圖展示了計(jì)算流程

旋轉(zhuǎn)基礎(chǔ)算法實(shí)現(xiàn)

旋轉(zhuǎn)點(diǎn)基礎(chǔ)

 /**
     * 旋轉(zhuǎn)點(diǎn)
     *
     * @param point 被旋轉(zhuǎn)的點(diǎn)
     * @param center 旋轉(zhuǎn)中心
     * @param angle 角度
     * @return 旋轉(zhuǎn)后坐標(biāo)
     */
    public static Coordinate get(Coordinate point, Coordinate center, double angle) {
        double cos = Math.cos(angle);
        double sin = Math.sin(angle);
        double x = point.x;
        double y = point.y;
        double centerX = center.x;
        double centerY = center.y;
        return new Coordinate(centerX + cos * (x - centerX) - sin * (y - centerY),
                centerY + sin * (x - centerX) + cos * (y - centerY));
    }

凸包算法實(shí)現(xiàn)

Geometry hull = (new ConvexHull(geom)).getConvexHull();

獲得結(jié)果

public static Polygon get(Geometry geom, GeometryFactory gf) {
        Geometry hull = (new ConvexHull(geom)).getConvexHull();
        if (!(hull instanceof Polygon)) {
            return null;
        }
        Polygon convexHull = (Polygon) hull;
        System.out.println(convexHull);

        // 直接使用中心值
        Coordinate c = geom.getCentroid().getCoordinate();
        System.out.println("==============旋轉(zhuǎn)基點(diǎn)==============");
        System.out.println(new GeometryFactory().createPoint(c));
        System.out.println("==============旋轉(zhuǎn)基點(diǎn)==============");
        Coordinate[] coords = convexHull.getExteriorRing().getCoordinates();

        double minArea = Double.MAX_VALUE;
        double minAngle = 0;
        Polygon ssr = null;
        Coordinate ci = coords[0];
        Coordinate cii;
        for (int i = 0; i < coords.length - 1; i++) {
            cii = coords[i + 1];
            double angle = Math.atan2(cii.y - ci.y, cii.x - ci.x);
            Polygon rect = (Polygon) Rotation.get(convexHull, c, -1 * angle, gf).getEnvelope();
            double area = rect.getArea();
//            此處可以將 rotationPolygon 放到list中求最小值
//            Polygon rotationPolygon = Rotation.get(rect, c, angle, gf);
//            System.out.println(rotationPolygon);
            if (area < minArea) {
                minArea = area;
                ssr = rect;
                minAngle = angle;
            }
            ci = cii;
        }

        return Rotation.get(ssr, c, minAngle, gf);
    }

測(cè)試類(lèi)

  @Test
    public void test() throws Exception{
        GeometryFactory gf = new GeometryFactory();
        String wkt = "POLYGON ((87623.0828822501 73753.4143904365,87620.1073981973 73739.213216548,87629.1690996309 73730.4220136646,87641.882531493 73727.3112803367,87643.0997749692 73714.8683470248,87662.0346734872 73725.0120426595,87669.0676357939 73735.1557382941,87655.9484561064 73735.9672339449,87676.9120937514 73747.4634223308,87651.8909778525 73740.8362078495,87659.4649372597 73755.4431295634,87644.4522677204 73748.680665807,87645.5342619215 73760.7178512935,87635.2553170117 73750.9799034842,87630.5215923822 73760.3121034681,87623.0828822501 73753.4143904365))";
        Polygon read = (Polygon) new WKTReader().read(wkt);
        Polygon polygon = MinimumBoundingRectangle.get(read, gf);

//        System.out.println(polygon);
//        System.out.println(polygon.getArea());

    }

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