264 lines
9.3 KiB
Markdown
264 lines
9.3 KiB
Markdown
---
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title: GeoTools 矢量网格(Vector Grid)
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date: 2023-12-20
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author: ac
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categories:
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- GIS
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tags:
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- GeoTools
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---
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## GeoTools 矢量网格(Vector Grid)
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### 1.简介
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`GeoTools` 的矢量网格化操作是
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GeoTools矢量网格类使得创建由多边形或线元素组成的矢量网格(也称为网格)变得容易，其中每一个都表示为SimpleFeature。可以使用grids或Lines实用程序类轻松生成简单的网格，而当需要对网格布局和属性进行更多控制时，可以使用较低级别的类。
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> 网格是在内存中构建的，整个网格一次构建。
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### 2.添加依赖
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```xml
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<dependency>
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<groupId>org.geotools</groupId>
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<artifactId>gt-grid</artifactId>
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<version>${geotools.version}</version>
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</dependency>
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```
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### 3. Polygon grids
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Grids实用类提供了创建**矩形**或**六边形**元素网格的方法。
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创建基本网格的最简单方法是使用Grids实用程序类中的静态方法。下面的例子创建了一个经纬度网格，其宽度为10度，用于显示在浙江地图上:
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```java
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public class Le08PolygonGrids {
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public static void main(String[] args) {
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String path = "D:\\demo\\tutorial\\data\\china\\zhejiang.shp";
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Le08PolygonGrids.readShpFile(path);
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}
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public static void readShpFile(String shpPath) {
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File shpFile = new File(shpPath);
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try {
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ShapefileDataStore shapefileDataStore = new ShapefileDataStore(shpFile.toURI().toURL());
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// 设置编码,防止属性的中文字符出现乱码
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shapefileDataStore.setCharset(Charset.forName("UTF-8"));
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// 这个typeNamae不传递，默认是文件名称
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FeatureSource featuresource = shapefileDataStore.getFeatureSource(shapefileDataStore.getTypeNames()[0]);
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// 读取bbox
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ReferencedEnvelope bbox =featuresource.getBounds();
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// 创建grids，0.2度为间隔
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SimpleFeatureSource grid = Grids.createSquareGrid(bbox, 0.2);
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// Create a map content and add our shapefile to it
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MapContent map = new MapContent();
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map.setTitle("polygon grids");
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// 添加shp到map中
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Style style = SLD.createSimpleStyle(featuresource.getSchema());
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Layer layer = new FeatureLayer(featuresource, style);
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map.addLayer(layer);
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Style styleBox = SLD.createSimpleStyle(grid.getSchema());
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Layer layerBox = new FeatureLayer(grid, styleBox);
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map.addLayer(layerBox);
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// Now display the map
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JMapFrame.showMap(map);
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} catch (IOException e) {
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e.printStackTrace();
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}
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System.out.println("读取完成！");
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}
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}
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```
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<img src="./images/image-20231220143856023.png" alt="image-20231220143856023" style="zoom:80%;width:50%" /><img src="./images/image-20231220144056349.png" alt="image-20231220144056349" style="zoom:80%;width:50%" />
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创建的网格由`SimpleFeatures`组成，每个`SimpleFeatures`都有一个最小多边形，即一个由四个角顶点表示的多边形。
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**选择性创建**
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新建一个网格生成类，继承`GridFeatureBuilder`，重写`getCreateFeature`方法来过滤与原数据要素不重叠得网格。
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```java
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package learning.tools;
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import java.io.IOException;
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import java.util.Map;
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import org.geotools.api.data.SimpleFeatureSource;
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import org.geotools.api.feature.simple.SimpleFeatureType;
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import org.geotools.api.filter.Filter;
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import org.geotools.api.filter.FilterFactory;
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import org.geotools.factory.CommonFactoryFinder;
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import org.geotools.geometry.jts.JTSFactoryFinder;
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import org.geotools.grid.GridElement;
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import org.geotools.grid.GridFeatureBuilder;
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import org.geotools.grid.PolygonElement;
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import org.locationtech.jts.geom.Coordinate;
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import org.locationtech.jts.geom.Geometry;
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import org.locationtech.jts.geom.GeometryFactory;
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public class IntersectionBuilder extends GridFeatureBuilder {
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final FilterFactory ff2 = CommonFactoryFinder.getFilterFactory();
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final GeometryFactory gf = JTSFactoryFinder.getGeometryFactory();
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final SimpleFeatureSource source;
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int id = 0;
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public IntersectionBuilder(SimpleFeatureType type, SimpleFeatureSource source) {
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super(type);
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this.source = source;
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}
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public void setAttributes(GridElement el, Map<String, Object> attributes) {
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attributes.put("id", ++id);
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}
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@Override
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public boolean getCreateFeature(GridElement el) {
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Coordinate c = ((PolygonElement) el).getCenter();
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Geometry p = gf.createPoint(c);
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Filter filter = ff2.intersects(ff2.property("the_geom"), ff2.literal(p));
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boolean result = false;
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try {
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result = !source.getFeatures(filter).isEmpty();
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} catch (IOException ex) {
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throw new IllegalStateException(ex);
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}
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return result;
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}
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}
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```
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```java
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package learning;
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import learning.tools.IntersectionBuilder;
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import org.geotools.api.data.FeatureSource;
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import org.geotools.api.data.Query;
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import org.geotools.api.data.SimpleFeatureSource;
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import org.geotools.api.feature.simple.SimpleFeature;
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import org.geotools.api.feature.simple.SimpleFeatureType;
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import org.geotools.api.feature.type.AttributeDescriptor;
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import org.geotools.api.feature.type.GeometryType;
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import org.geotools.api.geometry.BoundingBox;
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import org.geotools.api.referencing.crs.CoordinateReferenceSystem;
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import org.geotools.api.style.Style;
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import org.geotools.data.shapefile.ShapefileDataStore;
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import org.geotools.data.simple.SimpleFeatureCollection;
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import org.geotools.data.simple.SimpleFeatureIterator;
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import org.geotools.feature.simple.SimpleFeatureTypeBuilder;
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import org.geotools.geometry.jts.ReferencedEnvelope;
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import org.geotools.grid.GridElement;
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import org.geotools.grid.GridFeatureBuilder;
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import org.geotools.grid.Grids;
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import org.geotools.grid.PolygonElement;
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import org.geotools.map.FeatureLayer;
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import org.geotools.map.Layer;
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import org.geotools.map.MapContent;
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import org.geotools.referencing.crs.DefaultGeographicCRS;
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import org.geotools.styling.SLD;
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import org.geotools.swing.JMapFrame;
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import org.locationtech.jts.geom.Geometry;
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import org.locationtech.jts.geom.Polygon;
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import java.awt.*;
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import java.io.File;
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import java.io.IOException;
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import java.nio.charset.Charset;
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import java.util.LinkedList;
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import java.util.List;
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import java.util.Map;
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/**
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* @author ac
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* @date 2023/12/20 13:54
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*/
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public class Le08PolygonGrids {
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public static void main(String[] args) {
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String path = "D:\\demo\\tutorial\\data\\china\\zhejiang.shp";
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Le08PolygonGrids.readShpFile(path);
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}
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public static void readShpFile(String shpPath) {
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File shpFile = new File(shpPath);
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try {
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ShapefileDataStore shapefileDataStore = new ShapefileDataStore(shpFile.toURI().toURL());
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// 设置编码,防止属性的中文字符出现乱码
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shapefileDataStore.setCharset(Charset.forName("UTF-8"));
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// 这个typeNamae不传递，默认是文件名称
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FeatureSource featuresource = shapefileDataStore.getFeatureSource(shapefileDataStore.getTypeNames()[0]);
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// 读取bbox
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ReferencedEnvelope bbox =featuresource.getBounds();
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Double sideLen = 0.2;
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// 创建网格
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// 新建一份面要素shp，名叫grid，有两个字段id,the_geom
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SimpleFeatureTypeBuilder tb = new SimpleFeatureTypeBuilder();
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tb.setName("grid");
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tb.add(
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GridFeatureBuilder.DEFAULT_GEOMETRY_ATTRIBUTE_NAME,
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Polygon.class,
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bbox.getCoordinateReferenceSystem());
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tb.add("id", Integer.class);
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SimpleFeatureType TYPE = tb.buildFeatureType();
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// Build the grid the custom feature builder class
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GridFeatureBuilder builder = new IntersectionBuilder(TYPE, (SimpleFeatureSource)featuresource);
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SimpleFeatureSource grid = Grids.createHexagonalGrid(bbox, sideLen, -1, builder);
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// Create a map content and add our shapefile to it
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MapContent map = new MapContent();
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map.setTitle("polygon grids");
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// 添加shp到map中
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Style style = SLD.createSimpleStyle(featuresource.getSchema());
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Layer layer = new FeatureLayer(featuresource, style);
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map.addLayer(layer);
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Style styleBox = SLD.createSimpleStyle(grid.getSchema());
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Layer layerBox = new FeatureLayer(grid, styleBox);
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map.addLayer(layerBox);
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// Now display the map
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JMapFrame.showMap(map);
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} catch (IOException e) {
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e.printStackTrace();
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}
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System.out.println("读取完成！");
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}
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}
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```
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### 4.属性渲染
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到目前为止，没有一个示例需要为矢量网格指定 feature type特征类型。相反，我们用两个属性创建了一个默认的 feature type特性类型:
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- ‘element’ (the Polygon instance)
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- ‘id’ (a sequential integer ID value.
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当然，您也可以提供自己的特性类型，以便将其他属性与网格元素关联起来。要做到这一点，你需要重写GridFeatureBuilder类的setAttributes方法。下面的例子创建了一个带有' color '属性的特性类型。然后根据网格中每个六边形元素的位置设置颜色值:
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