自定义legend图形变形echarts scatter配置项内容和展示

如图，右下角top5的五角星被拉伸了，正常应该是图上闪光的点的那样。怎么让矢量图正常显示？

      var data = [
     {name: '海门', value: 9},
     {name: '鄂尔多斯', value: 12},
     {name: '招远', value: 12},
     {name: '舟山', value: 12},
     {name: '齐齐哈尔', value: 14},
     {name: '盐城', value: 15},
     {name: '赤峰', value: 16},
     {name: '青岛', value: 18},
     {name: '乳山', value: 18},
     {name: '金昌', value: 19},
     {name: '泉州', value: 21},
     {name: '莱西', value: 21},
     {name: '日照', value: 21},
     {name: '胶南', value: 22},
     {name: '南通', value: 23},
     {name: '拉萨', value: 24},
     {name: '云浮', value: 24},
     {name: '梅州', value: 25},
     {name: '文登', value: 25},
     {name: '上海', value: 25},
];
var geoCoordMap = {
    '海门':[121.15,31.89],
    '鄂尔多斯':[109.781327,39.608266],
    '招远':[120.38,37.35],
    '舟山':[122.207216,29.985295],
    '齐齐哈尔':[123.97,47.33],
    '盐城':[120.13,33.38],
    '赤峰':[118.87,42.28],
    '青岛':[120.33,36.07],
    '乳山':[121.52,36.89],
    '金昌':[102.188043,38.520089],
    '泉州':[118.58,24.93],
    '莱西':[120.53,36.86],
    '日照':[119.46,35.42],
    '胶南':[119.97,35.88],
    '南通':[121.05,32.08],
    '拉萨':[91.11,29.97],
    '云浮':[112.02,22.93],
    '梅州':[116.1,24.55],
    '文登':[122.05,37.2],
    '上海':[121.48,31.22],
};

var convertData = function (data) {
    var res = [];
    for (var i = 0; i < data.length; i++) {
        var geoCoord = geoCoordMap[data[i].name];
        if (geoCoord) {
            res.push({
                name: data[i].name,
                value: geoCoord.concat(data[i].value)
            });
        }
    }
    return res;
};

option = {
    backgroundColor: '#404a59',
    title: {
        text: '全国主要城市空气质量',
        subtext: 'data from PM25.in',
        sublink: 'http://www.pm25.in',
        left: 'center',
        textStyle: {
            color: '#fff'
        }
    },
    tooltip : {
        trigger: 'item'
    },
    legend: {
        orient: 'vertical',
        y: 'bottom',
        x:'right',
        data:['pm2.5','Top 5'],
        textStyle: {
            color: '#fff'
        },
        itemWidth: 14,    // 这里设置一下图标的宽高
          itemHeight: 14,
    },
    geo: {
        map: 'china',
        label: {
            emphasis: {
                show: false
            }
        },
        roam: true,
        itemStyle: {
            normal: {
                areaColor: '#323c48',
                borderColor: '#111'
            },
            emphasis: {
                areaColor: '#2a333d'
            }
        }
    },
    series : [
        {
            name: 'pm2.5',
            type: 'scatter',
            coordinateSystem: 'geo',
            data: convertData(data),
            symbolSize: function (val) {
                return val[2];
            },
            label: {
                normal: {
                    formatter: '{b}',
                    position: 'right',
                    show: false
                },
                emphasis: {
                    show: true
                }
            },
            itemStyle: {
                normal: {
                    color: '#ddb926'
                }
            }
        },
        {
            name: 'Top 5',
            type: 'effectScatter',
            coordinateSystem: 'geo',
            data: convertData(data.sort(function (a, b) {
                return b.value - a.value;
            }).slice(0, 6)),
            symbol:  'path://M551.498552,53.591355 L661.951153,277.426283 L935.218933,318.113961 C984.822678,325.511442 1000.40865,360.426649 963.954394,398.697278 L764.685978,593.817211 L813.540663,878.43755 C820.104149,919.637904 780.293445,943.584293 745.314792,919.637904 L495.587147,789.364885 L241.392772,922.953416 C207.354538,940.335295 172.354396,929.153628 178.704011,881.495189 L226.468874,593.8387 L21.10667,394.399391 C-18.554632,357.817218 2.056802,324.419573 48.089208,318.305319 L329.288635,277.446749 C329.288635,277.446749 386.994918,160.408149 439.613323,53.803179 C477.927953,-17.778112 519.940812,-16.730247 551.498552,53.591355 Z'
           ,
            symbolSize: function (val) {
                return val[2];
            },
            showEffectOn: 'render',
            rippleEffect: {
                brushType: 'stroke'
            },
            hoverAnimation: true,
            label: {
                normal: {
                    formatter: '{b}',
                    position: 'right',
                    show: true
                }
            },
            itemStyle: {
                normal: {
                    color: '#f4e925',
                    shadowBlur: 10,
                    shadowColor: '#333'
                }
            },
            zlevel: 1
        }
    ]
};