如何忽略边界而精确地检查一个多边形是否与另一个多边形重叠

Question

关于开放层中的拓扑和多边形之间的关系，我有一个问题。

情况是这样的：

使用https://turfjs.org/，我正在使用两种方法检查多边形是否重叠：https://turfjs.org/docs/#booleanOverlap和https://turfjs.org/docs/#booleanWithin，但是我得到了一些奇怪的交互作用。

如您所见，在蓝色rectangle中，多边形被捕捉为红色多边形，这是很好的行为，但是黄色矩形中的多边形存在问题，因为我得到了[[true并自动重叠红色样式。蓝色的多边形和黄色矩形的多边形仅捕捉到红色多边形的边界。

所以，我的问题是这个；是否有可能以某种方式忽略限制性多边形（红色）的边界，还是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;

Answer 1

我已经测试了booleanOverlap，尽管它似乎确实可以处理任何投影中的数字，但是为了符合草皮规范，建议通过缩小EPSG：3857坐标而不转换为投影来坚持较小的数字改变多边形的形状。缩放转换也可以比注释链接中的转换更简单。

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;