--- title: GeoTools 矢量网格(Vector Grid) date: 2023-12-20 author: ac categories: - GIS tags: - GeoTools --- ## GeoTools 矢量网格(Vector Grid) ### 1.简介 `GeoTools` 的矢量网格化操作是 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。 > 网格是在内存中构建的，整个网格一次构建。 ### 2.添加依赖 ```xml org.geotools gt-grid ${geotools.version} ``` ### 3. Polygon grids Grids实用类提供了创建**矩形**或**六边形**元素网格的方法。 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: ```java public class Le08PolygonGrids { public static void main(String[] args) { String path = "D:\\demo\\tutorial\\data\\china\\zhejiang.shp"; Le08PolygonGrids.readShpFile(path); } public static void readShpFile(String shpPath) { File shpFile = new File(shpPath); try { ShapefileDataStore shapefileDataStore = new ShapefileDataStore(shpFile.toURI().toURL()); // 设置编码,防止属性的中文字符出现乱码 shapefileDataStore.setCharset(Charset.forName("UTF-8")); // 这个typeNamae不传递，默认是文件名称 FeatureSource featuresource = shapefileDataStore.getFeatureSource(shapefileDataStore.getTypeNames()[0]); // 读取bbox ReferencedEnvelope bbox =featuresource.getBounds(); // 创建grids，0.2度为间隔 SimpleFeatureSource grid = Grids.createSquareGrid(bbox, 0.2); // Create a map content and add our shapefile to it MapContent map = new MapContent(); map.setTitle("polygon grids"); // 添加shp到map中 Style style = SLD.createSimpleStyle(featuresource.getSchema()); Layer layer = new FeatureLayer(featuresource, style); map.addLayer(layer); Style styleBox = SLD.createSimpleStyle(grid.getSchema()); Layer layerBox = new FeatureLayer(grid, styleBox); map.addLayer(layerBox); // Now display the map JMapFrame.showMap(map); } catch (IOException e) { e.printStackTrace(); } System.out.println("读取完成！"); } } ``` image-20231220143856023image-20231220144056349 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。 **选择性创建** 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。 ```java package learning.tools; import java.io.IOException; import java.util.Map; import org.geotools.api.data.SimpleFeatureSource; import org.geotools.api.feature.simple.SimpleFeatureType; import org.geotools.api.filter.Filter; import org.geotools.api.filter.FilterFactory; import org.geotools.factory.CommonFactoryFinder; import org.geotools.geometry.jts.JTSFactoryFinder; import org.geotools.grid.GridElement; import org.geotools.grid.GridFeatureBuilder; import org.geotools.grid.PolygonElement; import org.locationtech.jts.geom.Coordinate; import org.locationtech.jts.geom.Geometry; import org.locationtech.jts.geom.GeometryFactory; public class IntersectionBuilder extends GridFeatureBuilder { final FilterFactory ff2 = CommonFactoryFinder.getFilterFactory(); final GeometryFactory gf = JTSFactoryFinder.getGeometryFactory(); final SimpleFeatureSource source; int id = 0; public IntersectionBuilder(SimpleFeatureType type, SimpleFeatureSource source) { super(type); this.source = source; } public void setAttributes(GridElement el, Map attributes) { attributes.put("id", ++id); } @Override public boolean getCreateFeature(GridElement el) { Coordinate c = ((PolygonElement) el).getCenter(); Geometry p = gf.createPoint(c); Filter filter = ff2.intersects(ff2.property("the_geom"), ff2.literal(p)); boolean result = false; try { result = !source.getFeatures(filter).isEmpty(); } catch (IOException ex) { throw new IllegalStateException(ex); } return result; } } ``` ```java package learning; import learning.tools.IntersectionBuilder; import org.geotools.api.data.FeatureSource; import org.geotools.api.data.Query; import org.geotools.api.data.SimpleFeatureSource; import org.geotools.api.feature.simple.SimpleFeature; import org.geotools.api.feature.simple.SimpleFeatureType; import org.geotools.api.feature.type.AttributeDescriptor; import org.geotools.api.feature.type.GeometryType; import org.geotools.api.geometry.BoundingBox; import org.geotools.api.referencing.crs.CoordinateReferenceSystem; import org.geotools.api.style.Style; import org.geotools.data.shapefile.ShapefileDataStore; import org.geotools.data.simple.SimpleFeatureCollection; import org.geotools.data.simple.SimpleFeatureIterator; import org.geotools.feature.simple.SimpleFeatureTypeBuilder; import org.geotools.geometry.jts.ReferencedEnvelope; import org.geotools.grid.GridElement; import org.geotools.grid.GridFeatureBuilder; import org.geotools.grid.Grids; import org.geotools.grid.PolygonElement; import org.geotools.map.FeatureLayer; import org.geotools.map.Layer; import org.geotools.map.MapContent; import org.geotools.referencing.crs.DefaultGeographicCRS; import org.geotools.styling.SLD; import org.geotools.swing.JMapFrame; import org.locationtech.jts.geom.Geometry; import org.locationtech.jts.geom.Polygon; import java.awt.*; import java.io.File; import java.io.IOException; import java.nio.charset.Charset; import java.util.LinkedList; import java.util.List; import java.util.Map; /** * @author ac * @date 2023/12/20 13:54 */ public class Le08PolygonGrids { public static void main(String[] args) { String path = "D:\\demo\\tutorial\\data\\china\\zhejiang.shp"; Le08PolygonGrids.readShpFile(path); } public static void readShpFile(String shpPath) { File shpFile = new File(shpPath); try { ShapefileDataStore shapefileDataStore = new ShapefileDataStore(shpFile.toURI().toURL()); // 设置编码,防止属性的中文字符出现乱码 shapefileDataStore.setCharset(Charset.forName("UTF-8")); // 这个typeNamae不传递，默认是文件名称 FeatureSource featuresource = shapefileDataStore.getFeatureSource(shapefileDataStore.getTypeNames()[0]); // 读取bbox ReferencedEnvelope bbox =featuresource.getBounds(); Double sideLen = 0.2; // 创建网格 // 新建一份面要素shp，名叫grid，有两个字段id,the_geom SimpleFeatureTypeBuilder tb = new SimpleFeatureTypeBuilder(); tb.setName("grid"); tb.add( GridFeatureBuilder.DEFAULT_GEOMETRY_ATTRIBUTE_NAME, Polygon.class, bbox.getCoordinateReferenceSystem()); tb.add("id", Integer.class); SimpleFeatureType TYPE = tb.buildFeatureType(); // Build the grid the custom feature builder class GridFeatureBuilder builder = new IntersectionBuilder(TYPE, (SimpleFeatureSource)featuresource); SimpleFeatureSource grid = Grids.createHexagonalGrid(bbox, sideLen, -1, builder); // Create a map content and add our shapefile to it MapContent map = new MapContent(); map.setTitle("polygon grids"); // 添加shp到map中 Style style = SLD.createSimpleStyle(featuresource.getSchema()); Layer layer = new FeatureLayer(featuresource, style); map.addLayer(layer); Style styleBox = SLD.createSimpleStyle(grid.getSchema()); Layer layerBox = new FeatureLayer(grid, styleBox); map.addLayer(layerBox); // Now display the map JMapFrame.showMap(map); } catch (IOException e) { e.printStackTrace(); } System.out.println("读取完成！"); } } ``` ![image-20231221145539874](./images/image-20231221145539874.png) ### 4.属性渲染 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: - ‘element’ (the Polygon instance) - ‘id’ (a sequential integer ID value. 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: