如何通过手动修改GeoJson文件实现省级镂空Feature制作

如何通过手动修改GeoJson文件实现省级镂空Feature制作，针对这个问题，这篇文章详细介绍了相对应的分析和解答，希望可以帮助更多想解决这个问题的小伙伴找到更简单易行的方法。

一、先用QGIS绘制一个环形Feature并保存为GeoJson，看看环形Feature的数据结构是什么样

• 先绘制一个多边形，右键保存

• 在绘制好的多边形内添加环形(注意：这期间左下角一定要选中所编辑layer，否则会报错)

• 如果没有这个组件，右键工具栏，勾选Advanced Digitizing Toolbar

• 导出咱们刚刚画好的这个环形Feature为GeoJson

• 打开刚刚保存的GeoJson文件，看看它的数据结构，发现环形Feature的里外两个环的坐标数组都放在coordinates内，且外环在前，内环在后：

{
    "type": "FeatureCollection", 
    "name": "test", 
    "crs": {
        "type": "name", 
        "properties": {
            "name": "urn:ogc:def:crs:OGC:1.3:CRS84"
        }
    }, 
    "features": [
        {
            "type": "Feature", 
            "properties": {
                "id": 1
            }, 
            "geometry": {
                "type": "MultiPolygon", 
                "coordinates": [
                    [
                        [
                            [
                                98.62682583778792, 
                                54.32228639928258
                            ], 
                            [
                                109.40281163615893, 
                                55.957263554897494
                            ], 
                            [
                                116.64873312127047, 
                                55.02829926193448
                            ], 
                            [
                                117.35474598392236, 
                                52.94741924569732
                            ], 
                            [
                                114.64217024847035, 
                                51.832662094141696
                            ], 
                            [
                                112.7842416625443, 
                                50.68074637086755
                            ], 
                            [
                                103.71755016322525, 
                                50.792222086023116
                            ], 
                            [
                                98.62682583778792, 
                                54.32228639928258
                            ]
                        ], 
                        [
                            [
                                103.9976189834291, 
                                53.8974727328586
                            ], 
                            [
                                105.91267520881026, 
                                51.91148849913
                            ], 
                            [
                                107.99323012033545, 
                                54.18118476624841
                            ], 
                            [
                                103.9976189834291, 
                                53.8974727328586
                            ]
                        ]
                    ]
                ]
            }
        }
    ]
}

二、着手制作镂空的内蒙区域GeoJson

了解环形Feature的GeoJson结构之后，接下来我们可以把现有的内蒙古区域GeoJson改造一下，让它变成镂空的。

• 用QGIS画个方框，一定要把内蒙整个包进去，然后获得这个方框的坐标数组，具体过程不作赘述

• 我这获得的坐标数组：

[ [ 70.35465968686151, 73.302099634723305 ], [ 158.04277887424999, 73.181814148869549 ], [ 157.922493388396219, 11.234788934184962 ], [ 70.114088715153997, 12.317358306868769 ], [ 70.35465968686151, 73.302099634723305 ] ]

• 修改内蒙的GeoJson文件，把上一步获得的坐标数组加到内蒙边界坐标数组前边

• 加载一下修改好的GeoJson看看效果：

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