如何通過手動(dòng)修改GeoJson文件實(shí)現(xiàn)省級(jí)鏤空Feature制作

如何通過手動(dòng)修改GeoJson文件實(shí)現(xiàn)省級(jí)鏤空Feature制作，針對(duì)這個(gè)問題，這篇文章詳細(xì)介紹了相對(duì)應(yīng)的分析和解答，希望可以幫助更多想解決這個(gè)問題的小伙伴找到更簡(jiǎn)單易行的方法。

一、先用QGIS繪制一個(gè)環(huán)形Feature并保存為GeoJson，看看環(huán)形Feature的數(shù)據(jù)結(jié)構(gòu)是什么樣

• 先繪制一個(gè)多邊形，右鍵保存

• 在繪制好的多邊形內(nèi)添加環(huán)形(注意：這期間左下角一定要選中所編輯layer，否則會(huì)報(bào)錯(cuò))

• 如果沒有這個(gè)組件，右鍵工具欄，勾選Advanced Digitizing Toolbar

• 導(dǎo)出咱們剛剛畫好的這個(gè)環(huán)形Feature為GeoJson

• 打開剛剛保存的GeoJson文件，看看它的數(shù)據(jù)結(jié)構(gòu)，發(fā)現(xiàn)環(huán)形Feature的里外兩個(gè)環(huán)的坐標(biāo)數(shù)組都放在coordinates內(nèi)，且外環(huán)在前，內(nèi)環(huán)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、著手制作鏤空的內(nèi)蒙區(qū)域GeoJson

了解環(huán)形Feature的GeoJson結(jié)構(gòu)之后，接下來我們可以把現(xiàn)有的內(nèi)蒙古區(qū)域GeoJson改造一下，讓它變成鏤空的。

• 用QGIS畫個(gè)方框，一定要把內(nèi)蒙整個(gè)包進(jìn)去，然后獲得這個(gè)方框的坐標(biāo)數(shù)組，具體過程不作贅述

• 我這獲得的坐標(biāo)數(shù)組：

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

• 修改內(nèi)蒙的GeoJson文件，把上一步獲得的坐標(biāo)數(shù)組加到內(nèi)蒙邊界坐標(biāo)數(shù)組前邊

• 加載一下修改好的GeoJson看看效果：

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