;


                const centerPt = layer.coordinateToVector3(lineString.getCenter());
                //cache position for  faster computing,reduce double counting
                const positionMap = {};
                for (let i = 0, len = chunkLines.length; i < len; i++) {
                    const chunkLine = chunkLines[i];
                    for (let j = 0, len1 = chunkLine.length; j < len1; j++) {
                        const lnglat = chunkLine[j];
                        const key = lnglat.join('