如何在忽略边界的情况下精确检查一个多边形是否与另一个多边形重叠

Question

我有一个关于 openlayers 中多边形之间的拓扑和关系的问题。

情况是这样的：

使用 https://turfjs.org/ I'm using two methods to check if polygons are overlapping, https://turfjs.org/docs/#booleanOverlap and https://turfjs.org/docs/#booleanWithin 但我遇到了一些奇怪的交互。

如您所见，在蓝色矩形中，多边形被捕捉到红色多边形，这是很好的行为，但问题在于黄色矩形中的多边形，我得到 true 并自动重叠红色样式。蓝色多边形和黄色矩形多边形仅捕捉到红色多边形的边界。

所以，我的问题是这样的；是否有可能以某种方式忽略限制性多边形（红色）的边界，或者我应该找到另一种方法。

我正在检查多边形是否重叠的代码示例：

 vectorLayer.getSource().on(OpenLayersEvents.AddFeature, (evt: any) => {


            let feature = evt.feature;


            // clip area function with return geometry value
            let polygon = clipFieldArea(feature, this.myRestrictionVectorLayer);


            let isFeatureOverlappingFlag = false;
            //red polygons
            if (this.restrictiveLayer.getSource().getFeatures().length > 0) {
                isFeatureOverlappingFlag = arePolygonsOverlapping(feature, this.restrictiveLayer); 
            }

            // checks if features are overlapping then set new style
            feature.getGeometry().setCoordinates(polygon.getCoordinates());
            if (isFeatureOverlappingFlag) {
                feature.setStyle(this.featureOverlappingStyle);
            } else {
                feature.setStyle(this.fieldStyle);
            }....

这里是 arePolygonsOverlapping() 检查拓扑的方法

   let geojsonFormat = new GeoJSON();

    let areOverlapping: boolean = false;

    let flagCheck: boolean = false;
    let restrictionFeatures = restrictionLayer.getSource().getFeatures();

    // create GeoJSON object and transform it in WGS84 for intersect method
    let firstGeometryObject = geojsonFormat.writeFeatureObject(feature, { dataProjection: 'EPSG:4326', featureProjection: 'EPSG:3857' });

    for (let featureRestrict of restrictionFeatures) {

        let secondGeometryObject = geojsonFormat.writeFeatureObject(featureRestrict,
            { dataProjection: 'EPSG:4326', featureProjection: 'EPSG:3857' });

        areOverlapping = booleanOverlap(firstGeometryObject as unknown as TurfPolygon, secondGeometryObject as unknown as TurfPolygon);

        if (areOverlapping) {
            flagCheck = true;
            break;
        }
    }
    return flagCheck;

更新

我尝试使用 Mike 提出的解决方案，但我得到了 Uncaught TypeError: ol_proj__WEBPACK_IMPORTED_MODULE_3__.default.Projection is not a constructor

尝试创建新投影时。这是更新的方法

export function arePolygonsOverlapping(feature: any, restrictionLayer: VectorLayer): boolean {

    let areOverlapping: boolean = false;

    let flagCheck: boolean = false;
    let restrictionFeatures = restrictionLayer.getSource().getFeatures();

    //#region "Parameters for scaling down coordinates"
        let viewProjection = Projection.get('EPSG:3857');
        let smallProjection = Projection.get('small');

    if (!smallProjection) {
        smallProjection = new Projection.Projection({
            code: 'small',
            units: 'm'
        });

        Projection.addProjection(smallProjection);

        let scale = Extent.getWidth(viewProjection.getExtent());

        let smallTransform = function (coordinate: [number, number]) {
            return [coordinate[0] / scale, coordinate[1] / scale];
        }

        let normalTransform = function (coordinate: [number, number]) {
            return [coordinate[0] * scale, coordinate[1] * scale];
        }

        Projection.addCoordinateTransforms(viewProjection, smallProjection, smallTransform as any, normalTransform as any);

    }
    //#endregion "Parameters for scaling down coordinates"


    // create GeoJSON object and transform it in WGS84 for intersect method
    let firstGeometryObject = geojsonFormat.writeFeatureObject(feature, { dataProjection: smallProjection, featureProjection: viewProjection  });

    for (let featureRestrict of restrictionFeatures) {

        let secondGeometryObject = geojsonFormat.writeFeatureObject(featureRestrict,
            { dataProjection: smallProjection, featureProjection: viewProjection  });

        areOverlapping = booleanOverlap(firstGeometryObject as unknown as TurfPolygon, secondGeometryObject as unknown as TurfPolygon);

        if (areOverlapping) {
            flagCheck = true;
            break;
        }
    }
    return flagCheck;
}

这是我的导入：

import Extent from 'ol/extent';
import Projection from 'ol/proj';

我忘了说我使用的是 v 4.6.2

Answer 1

我已经测试了 booleanOverlap，虽然它似乎确实适用于任何投影的数字，但为了符合草坪规范，建议通过缩小 [=14= 来坚持使用较小的数字] 坐标而不转换为改变多边形形状的投影。缩放变换也可以比评论链接中的更简单。

import { getWidth } from 'ol/extent';
import { Projection, addCoordinateTransforms, addProjection, get as getProjection } from 'ol/proj';

....
....


let viewProjection = getProjection('EPSG:3857');
let smallProjection = getProjection('small');

if (!smallProjection) {

    smallProjection = new Projection({
        code: 'small',
        units: 'm'
    });
    addProjection(smallProjection);

    let scale = getWidth(viewProjection.getExtent());

    let smallTransform = function(coordinate) {
        return [coordinate[0] / scale, coordinate[1] / scale];
    }

    let normalTransform = function(coordinate) {
        return [coordinate[0] * scale, coordinate[1] * scale];
    }

    addCoordinateTransforms(viewProjection, smallProjection, smallTransform, normalTransform);

}

let geojsonFormat = new GeoJSON();

let areOverlapping: boolean = false;

let flagCheck: boolean = false;
let restrictionFeatures = restrictionLayer.getSource().getFeatures();

// create GeoJSON object and transform it in WGS84 for intersect method
let firstGeometryObject = geojsonFormat.writeFeatureObject(feature, { dataProjection: smallProjection, featureProjection: viewProjection });

for (let featureRestrict of restrictionFeatures) {

    let secondGeometryObject = geojsonFormat.writeFeatureObject(featureRestrict,
        { dataProjection: smallProjection, featureProjection: viewProjection });

    areOverlapping = booleanOverlap(firstGeometryObject as unknown as TurfPolygon, secondGeometryObject as unknown as TurfPolygon);

    if (areOverlapping) {
        flagCheck = true;
        break;
    }
}
return flagCheck;

Answer 2

好的，我在这件事上采取了不同的方式。而不是 "fixing" 和调整坐标（尽管如此，迈克的回答中很好地指出我们应该缩小坐标）

我刚刚使用了 Turf 相交方法并通过附加区域检查检查是否存在任何相交要素。

这种方法涵盖了我一直在尝试的大多数情况

let isIntersecting: boolean = false;

let flagCheck: boolean = false;
let restrictionFeatures = restrictionLayer.getSource().getFeatures();

// create GeoJSON object and transform it in WGS84 for intersect method
let firstGeometryObject = geojsonFormat.writeFeatureObject(feature, { dataProjection: 'EPSG:4326', featureProjection: 'EPSG:3857' }) as unknown as TurfPolygon;

for (let featureRestrict of restrictionFeatures) {

    let secondGeometryObject = geojsonFormat.writeFeatureObject(featureRestrict,
        { dataProjection: 'EPSG:4326', featureProjection: 'EPSG:3857' }) as unknown as TurfPolygon;

    // get intersected polgon
    let intersectPolygon = intersect(firstGeometryObject, secondGeometryObject);

    if (intersectPolygon != null) {
        isIntersecting = true;

        // calculate value of intersected area
        let areaValue: number = area(intersectPolygon as unknown as AllGeoJSON);

        // area below 10 meters is considered overlapping
        if (areaValue < 10) {
            isIntersecting = false;
        }
    }

    if (isIntersecting) {
        flagCheck = true;
        break;
    }
}
return flagCheck;

如何在忽略边界的情况下精确检查一个多边形是否与另一个多边形重叠

How to precisely check if one polygon overlaps another while ignoring boundary

topology

openlayers

openlayers-3

turfjs

openlayers-5