第08章 - OGC兼容开发

第08章 - OGC兼容开发

8.1 OGC Simple Feature 规范

8.1.1 规范概述

OGC Simple Feature Access (SFA) 是开放地理空间联盟定义的几何数据模型和操作标准。geometry-api-java 通过 com.esri.core.geometry.ogc 包提供完整的 OGC 兼容支持。

OGC 几何类型层次：

Geometry
├── Point
├── Curve
│   └── LineString
│       └── LinearRing
├── Surface
│   └── Polygon
└── GeometryCollection
    ├── MultiPoint
    ├── MultiCurve
    │   └── MultiLineString
    └── MultiSurface
        └── MultiPolygon

8.1.2 ESRI 与 OGC 几何的对比

OGC 类型	ESRI 类型	关键区别
Point	Point	基本相同
LineString	Polyline (单路径)	OGC 是单路径
Polygon	Polygon (单外环)	OGC 严格单外环
MultiPoint	MultiPoint	基本相同
MultiLineString	Polyline (多路径)	OGC 明确多线串
MultiPolygon	Polygon (多外环)	OGC 明确多多边形
GeometryCollection	无直接对应	OGC 特有

8.1.3 OGC 几何类层次

// OGC 几何类继承关系
com.esri.core.geometry.ogc
├── OGCGeometry                    // 抽象基类
├── OGCPoint                       // 点
├── OGCCurve                       // 曲线（抽象）
│   └── OGCLineString             // 线串
│       └── OGCLinearRing         // 线环
├── OGCSurface                     // 面（抽象）
│   └── OGCPolygon                // 多边形
├── OGCGeometryCollection          // 几何集合（抽象）
│   ├── OGCMultiPoint             // 多点
│   ├── OGCMultiCurve             // 多曲线（抽象）
│   │   └── OGCMultiLineString    // 多线串
│   ├── OGCMultiSurface           // 多面（抽象）
│   │   └── OGCMultiPolygon       // 多多边形
│   └── OGCConcreteGeometryCollection // 具体几何集合

8.2 OGCGeometry 基类

8.2.1 通用方法

// OGCGeometry 提供的通用方法
public abstract class OGCGeometry {
    // 维度信息
    public int dimension();           // 几何维度 (0, 1, 2)
    public int coordinateDimension(); // 坐标维度 (2, 3, 4)
    
    // 类型信息
    public abstract String geometryType();
    public int SRID();
    
    // 属性判断
    public boolean isEmpty();
    public boolean isSimple();
    public boolean is3D();
    public boolean isMeasured();
    
    // 边界和包络
    public abstract OGCGeometry boundary();
    public OGCGeometry envelope();
    
    // 空间关系
    public boolean Equals(OGCGeometry another);
    public boolean disjoint(OGCGeometry another);
    public boolean intersects(OGCGeometry another);
    public boolean touches(OGCGeometry another);
    public boolean crosses(OGCGeometry another);
    public boolean within(OGCGeometry another);
    public boolean contains(OGCGeometry another);
    public boolean overlaps(OGCGeometry another);
    public boolean relate(OGCGeometry another, String matrix);
    
    // 空间操作
    public double distance(OGCGeometry another);
    public OGCGeometry buffer(double distance);
    public OGCGeometry convexHull();
    public OGCGeometry intersection(OGCGeometry another);
    public OGCGeometry union(OGCGeometry another);
    public OGCGeometry difference(OGCGeometry another);
    public OGCGeometry symDifference(OGCGeometry another);
    
    // 格式转换
    public String asText();           // 转 WKT
    public ByteBuffer asBinary();     // 转 WKB
    public String asGeoJson();        // 转 GeoJSON
    public String asJson();           // 转 ESRI JSON
    
    // 与 ESRI 几何互转
    public abstract Geometry getEsriGeometry();
    public SpatialReference getEsriSpatialReference();
    
    // 类型转换
    public abstract OGCGeometry convertToMulti();
    public abstract OGCGeometry reduceFromMulti();
}

8.2.2 创建 OGC 几何

// 从 WKT 创建
OGCGeometry geom = OGCGeometry.fromText("POINT (116.4 39.9)");

// 从 WKB 创建
byte[] wkbBytes = getWkbData();
OGCGeometry geom2 = OGCGeometry.fromBinary(ByteBuffer.wrap(wkbBytes));

// 从 GeoJSON 创建
String geoJson = "{\"type\":\"Point\",\"coordinates\":[116.4,39.9]}";
OGCGeometry geom3 = OGCGeometry.fromGeoJson(geoJson);

// 从 ESRI JSON 创建
String esriJson = "{\"x\":116.4,\"y\":39.9}";
OGCGeometry geom4 = OGCGeometry.fromJson(esriJson);

// 从 ESRI Shape 创建
byte[] shapeBytes = getShapeData();
OGCGeometry geom5 = OGCGeometry.fromEsriShape(ByteBuffer.wrap(shapeBytes));

// 从 ESRI Geometry 创建
Point esriPoint = new Point(116.4, 39.9);
SpatialReference sr = SpatialReference.create(4326);
OGCGeometry geom6 = OGCGeometry.createFromEsriGeometry(esriPoint, sr);

8.3 OGC 点几何

8.3.1 OGCPoint

// 创建 OGCPoint
OGCPoint point = (OGCPoint) OGCGeometry.fromText("POINT (116.4 39.9)");

// 或从 ESRI Point 创建
Point esriPoint = new Point(116.4, 39.9);
OGCPoint point2 = new OGCPoint(esriPoint, SpatialReference.create(4326));

// OGCPoint 特有方法
double x = point.X();
double y = point.Y();
double z = point.Z();  // 如果有 Z
double m = point.M();  // 如果有 M

// 类型
String type = point.geometryType();  // "Point"

8.3.2 OGCMultiPoint

// 创建 OGCMultiPoint
OGCMultiPoint multiPoint = (OGCMultiPoint) OGCGeometry.fromText(
    "MULTIPOINT ((0 0), (10 10), (20 20))");

// 或从 ESRI MultiPoint 创建
MultiPoint esriMultiPoint = new MultiPoint();
esriMultiPoint.add(0, 0);
esriMultiPoint.add(10, 10);
OGCMultiPoint mp2 = new OGCMultiPoint(esriMultiPoint, null);

// OGCMultiPoint 特有方法
int numPoints = multiPoint.numGeometries();
OGCPoint firstPoint = (OGCPoint) multiPoint.geometryN(0);

8.4 OGC 线几何

8.4.1 OGCLineString

// 创建 OGCLineString
OGCLineString line = (OGCLineString) OGCGeometry.fromText(
    "LINESTRING (0 0, 10 10, 20 0)");

// 或从 ESRI Polyline 创建
Polyline esriLine = new Polyline();
esriLine.startPath(0, 0);
esriLine.lineTo(10, 10);
esriLine.lineTo(20, 0);
OGCLineString line2 = new OGCLineString(esriLine, 0, null);

// OGCLineString 特有方法
int numPoints = line.numPoints();
OGCPoint startPoint = line.startPoint();
OGCPoint endPoint = line.endPoint();
boolean isClosed = line.isClosed();
boolean isRing = line.isRing();  // 闭合且简单
double length = line.length();

// 获取任意点
OGCPoint pointN = line.pointN(1);

8.4.2 OGCMultiLineString

// 创建 OGCMultiLineString
OGCMultiLineString multiLine = (OGCMultiLineString) OGCGeometry.fromText(
    "MULTILINESTRING ((0 0, 10 10), (20 20, 30 30))");

// OGCMultiLineString 特有方法
int numLineStrings = multiLine.numGeometries();
OGCLineString firstLine = (OGCLineString) multiLine.geometryN(0);
double totalLength = multiLine.length();
boolean isClosed = multiLine.isClosed();  // 所有组成线都闭合

8.4.3 OGCLinearRing

// OGCLinearRing 是闭合的简单 LineString
// 通常作为 Polygon 的组成部分，不单独使用

String wkt = "LINEARRING (0 0, 10 0, 10 10, 0 10, 0 0)";
// 注意：许多 WKT 解析器不支持 LINEARRING 类型

8.5 OGC 面几何

8.5.1 OGCPolygon

// 创建 OGCPolygon
OGCPolygon polygon = (OGCPolygon) OGCGeometry.fromText(
    "POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0))");

// 带孔洞的多边形
OGCPolygon polygonWithHole = (OGCPolygon) OGCGeometry.fromText(
    "POLYGON ((0 0, 20 0, 20 20, 0 20, 0 0), (5 5, 5 15, 15 15, 15 5, 5 5))");

// 或从 ESRI Polygon 创建
Polygon esriPolygon = new Polygon();
esriPolygon.startPath(0, 0);
esriPolygon.lineTo(10, 0);
esriPolygon.lineTo(10, 10);
esriPolygon.lineTo(0, 10);
esriPolygon.closePathWithLine();
OGCPolygon polygon2 = new OGCPolygon(esriPolygon, 0, null);

// OGCPolygon 特有方法
OGCLineString exteriorRing = polygon.exteriorRing();
int numInteriorRings = polygon.numInteriorRing();
OGCLineString interiorRing = polygon.interiorRingN(0);
double area = polygon.area();
OGCPoint centroid = polygon.centroid();
OGCPoint pointOnSurface = polygon.pointOnSurface();

8.5.2 OGCMultiPolygon

// 创建 OGCMultiPolygon
OGCMultiPolygon multiPolygon = (OGCMultiPolygon) OGCGeometry.fromText(
    "MULTIPOLYGON (((0 0, 10 0, 10 10, 0 10, 0 0)), " +
    "((20 20, 30 20, 30 30, 20 30, 20 20)))");

// OGCMultiPolygon 特有方法
int numPolygons = multiPolygon.numGeometries();
OGCPolygon firstPolygon = (OGCPolygon) multiPolygon.geometryN(0);
double totalArea = multiPolygon.area();
OGCPoint centroid = multiPolygon.centroid();

8.6 OGC 几何集合

8.6.1 OGCGeometryCollection

// 创建 OGCConcreteGeometryCollection
OGCGeometry collection = OGCGeometry.fromText(
    "GEOMETRYCOLLECTION (POINT (0 0), LINESTRING (0 0, 10 10))");

OGCConcreteGeometryCollection gc = (OGCConcreteGeometryCollection) collection;

// OGCGeometryCollection 方法
int numGeometries = gc.numGeometries();

for (int i = 0; i < numGeometries; i++) {
    OGCGeometry geom = gc.geometryN(i);
    System.out.println(geom.geometryType());
}

8.6.2 创建 GeometryCollection

// 从多个 OGCGeometry 创建
List<OGCGeometry> geometries = new ArrayList<>();
geometries.add(OGCGeometry.fromText("POINT (0 0)"));
geometries.add(OGCGeometry.fromText("LINESTRING (0 0, 10 10)"));
geometries.add(OGCGeometry.fromText("POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0))"));

OGCConcreteGeometryCollection collection = 
    new OGCConcreteGeometryCollection(geometries, SpatialReference.create(4326));

8.6.3 遍历 GeometryCollection

public void processGeometryCollection(OGCGeometry geometry) {
    if (geometry instanceof OGCConcreteGeometryCollection) {
        OGCConcreteGeometryCollection gc = (OGCConcreteGeometryCollection) geometry;
        for (int i = 0; i < gc.numGeometries(); i++) {
            processGeometryCollection(gc.geometryN(i));  // 递归
        }
    } else {
        // 处理单个几何
        System.out.println(geometry.geometryType() + ": " + geometry.asText());
    }
}

8.7 OGC 空间操作

8.7.1 空间关系

OGCPolygon polygon = (OGCPolygon) OGCGeometry.fromText(
    "POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0))");
OGCPoint point = (OGCPoint) OGCGeometry.fromText("POINT (5 5)");

// 空间关系判断
boolean contains = polygon.contains(point);
boolean within = point.within(polygon);
boolean intersects = polygon.intersects(point);
boolean disjoint = polygon.disjoint(point);
boolean touches = polygon.touches(point);
boolean equals = polygon.Equals(polygon);

// DE-9IM 关系
boolean relate = polygon.relate(point, "T*F**F***");  // contains 模式

8.7.2 空间操作

OGCPolygon p1 = (OGCPolygon) OGCGeometry.fromText(
    "POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0))");
OGCPolygon p2 = (OGCPolygon) OGCGeometry.fromText(
    "POLYGON ((5 5, 15 5, 15 15, 5 15, 5 5))");

// 缓冲区
OGCGeometry buffer = p1.buffer(2.0);

// 凸包
OGCGeometry hull = p1.convexHull();

// 布尔操作
OGCGeometry intersection = p1.intersection(p2);
OGCGeometry union = p1.union(p2);
OGCGeometry difference = p1.difference(p2);
OGCGeometry symDiff = p1.symDifference(p2);

// 距离
double distance = p1.distance(p2);

8.7.3 简化操作

OGCGeometry geometry = OGCGeometry.fromText("POLYGON (...)");

// 检查是否简单
boolean isSimple = geometry.isSimple();

// 使几何简单化（OGC 规则）
OGCGeometry simplified = geometry.makeSimple();

// 使几何简单化（Geodatabase 规则，更宽松）
OGCGeometry simplifiedRelaxed = geometry.makeSimpleRelaxed(true);

8.8 类型转换

8.8.1 OGC 与 ESRI 几何互转

// OGC → ESRI
OGCPolygon ogcPolygon = (OGCPolygon) OGCGeometry.fromText(
    "POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0))");
Geometry esriGeom = ogcPolygon.getEsriGeometry();
SpatialReference sr = ogcPolygon.getEsriSpatialReference();

// ESRI → OGC
Polygon esriPolygon = new Polygon();
esriPolygon.startPath(0, 0);
esriPolygon.lineTo(10, 0);
esriPolygon.lineTo(10, 10);
esriPolygon.lineTo(0, 10);
esriPolygon.closePathWithLine();

OGCGeometry ogcGeom = OGCGeometry.createFromEsriGeometry(
    esriPolygon, SpatialReference.create(4326));

8.8.2 单一类型与多类型转换

// 转换为多类型
OGCPoint point = (OGCPoint) OGCGeometry.fromText("POINT (0 0)");
OGCGeometry multiPoint = point.convertToMulti();
System.out.println(multiPoint.geometryType());  // "MultiPoint"

// 从多类型简化
OGCMultiPoint mp = (OGCMultiPoint) OGCGeometry.fromText("MULTIPOINT ((0 0))");
OGCGeometry reduced = mp.reduceFromMulti();
System.out.println(reduced.geometryType());  // "Point"

8.9 格式转换

8.9.1 WKT 读写

// 从 WKT 读取
OGCGeometry geom = OGCGeometry.fromText("POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0))");

// 写入 WKT
String wkt = geom.asText();
System.out.println(wkt);

8.9.2 WKB 读写

// 从 WKB 读取
byte[] wkbBytes = getWkbData();
OGCGeometry geom = OGCGeometry.fromBinary(ByteBuffer.wrap(wkbBytes));

// 写入 WKB
ByteBuffer wkb = geom.asBinary();
byte[] bytes = new byte[wkb.remaining()];
wkb.get(bytes);

8.9.3 GeoJSON 读写

// 从 GeoJSON 读取
String geoJson = "{\"type\":\"Polygon\",\"coordinates\":[[[0,0],[10,0],[10,10],[0,10],[0,0]]]}";
OGCGeometry geom = OGCGeometry.fromGeoJson(geoJson);

// 写入 GeoJSON
String outputGeoJson = geom.asGeoJson();
System.out.println(outputGeoJson);

8.10 实战应用

8.10.1 空间查询封装

public class OGCSpatialQuery {
    private SpatialReference sr;
    
    public OGCSpatialQuery(int srid) {
        this.sr = SpatialReference.create(srid);
    }
    
    /**
     * 查找包含指定点的多边形
     */
    public List<OGCPolygon> findContaining(OGCPoint point, List<OGCPolygon> polygons) {
        List<OGCPolygon> result = new ArrayList<>();
        for (OGCPolygon polygon : polygons) {
            if (polygon.contains(point)) {
                result.add(polygon);
            }
        }
        return result;
    }
    
    /**
     * 查找与指定几何相交的几何
     */
    public List<OGCGeometry> findIntersecting(OGCGeometry query, List<OGCGeometry> geometries) {
        List<OGCGeometry> result = new ArrayList<>();
        for (OGCGeometry geom : geometries) {
            if (query.intersects(geom)) {
                result.add(geom);
            }
        }
        return result;
    }
    
    /**
     * 缓冲区查询
     */
    public List<OGCGeometry> findWithinDistance(OGCGeometry center, 
            double distance, List<OGCGeometry> geometries) {
        OGCGeometry buffer = center.buffer(distance);
        return findIntersecting(buffer, geometries);
    }
}

8.10.2 几何验证

public class OGCGeometryValidator {
    
    /**
     * 验证几何是否符合 OGC 标准
     */
    public ValidationResult validate(OGCGeometry geometry) {
        ValidationResult result = new ValidationResult();
        
        // 检查是否为空
        if (geometry.isEmpty()) {
            result.addIssue("几何为空");
            return result;
        }
        
        // 检查是否简单
        if (!geometry.isSimple()) {
            result.addIssue("几何不简单（可能自相交）");
        }
        
        // 特定类型检查
        if (geometry instanceof OGCPolygon) {
            validatePolygon((OGCPolygon) geometry, result);
        } else if (geometry instanceof OGCLineString) {
            validateLineString((OGCLineString) geometry, result);
        }
        
        return result;
    }
    
    private void validatePolygon(OGCPolygon polygon, ValidationResult result) {
        // 检查外环方向
        OGCLineString exterior = polygon.exteriorRing();
        if (!isCounterClockwise(exterior)) {
            result.addWarning("外环应为逆时针方向");
        }
        
        // 检查内环方向
        for (int i = 0; i < polygon.numInteriorRing(); i++) {
            OGCLineString interior = polygon.interiorRingN(i);
            if (!isClockwise(interior)) {
                result.addWarning("内环 " + i + " 应为顺时针方向");
            }
        }
        
        // 检查面积
        if (polygon.area() <= 0) {
            result.addIssue("多边形面积非正");
        }
    }
    
    private void validateLineString(OGCLineString line, ValidationResult result) {
        if (line.numPoints() < 2) {
            result.addIssue("线串至少需要2个点");
        }
    }
    
    private boolean isCounterClockwise(OGCLineString ring) {
        // 简化实现：使用面积符号判断
        Polyline polyline = (Polyline) ring.getEsriGeometry();
        Polygon tempPolygon = new Polygon();
        tempPolygon.addPath(polyline, 0, true);
        return tempPolygon.calculateRingArea2D(0) > 0;
    }
    
    private boolean isClockwise(OGCLineString ring) {
        return !isCounterClockwise(ring);
    }
}

8.11 本章小结

本章详细介绍了 geometry-api-java 的 OGC 兼容开发：

1. OGC 规范：Simple Feature Access 标准
2. OGC 几何类：Point、LineString、Polygon 等
3. 几何集合：GeometryCollection 及其子类
4. 空间操作：关系判断和布尔运算
5. 类型转换：OGC 与 ESRI 几何互转
6. 格式转换：WKT、WKB、GeoJSON
7. 实战应用：空间查询和几何验证

关键要点：

• OGC 类型更严格，适合标准化场景
• 使用 OGCGeometry 进行跨平台数据交换
• 注意 OGC 与 ESRI 几何的差异
• 使用 makeSimple() 确保几何符合 OGC 规范

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