【GIS教程】使用GDAL-Python将tif转为COG并在ArcGIS Js前端加载-附完整代码

from osgeo import gdal, gdalconst

'''获取相应统计数据'''
def compute_stat(srcDS):
    outBand = srcDS.GetRasterBand(1)
    stat = outBand.ComputeStatistics(True)

    outBand = None
    stat = None
    del outBand
    del stat


# 将文件转为cog
file = "./Data/DSM22000108.tif" # 输入数据
out = "./Data/DSM22000108-COG.tif" #输出数据
cal_area = gdal.Open(file) # 读取

# ---------------------
#----写法1：添加多个参数设定COG格式----
options = gdal.TranslateOptions(
    format="COG",
    creationOptions=[
        "COMPRESS=DEFLATE",
        "TILING_SCHEME=GoogleMapsCompatible",
        "QUALITY=100",
        "BLOCKSIZE=256",
        "BIGTIFF=YES",
        "NUM_THREADS=ALL_CPUS"
     ],
     outputType=gdalconst.GDT_Int32
)
# 转换为COG格式数据
desImg = gdal.Translate(out, cal_area, options=options, overwrite=True)

#----写法2：使用默认参数----
desImg = gdal.Translate(out, cal_area, format="COG")

# ---------------------

#计算COG的栅格值，生成xml
n_desImg = gdal.Open(out)
compute_stat(n_desImg)

print("out img---------------")
print(n_desImg)

n_desImg = None

得到的结果为：

四、使用ArcGIS Maps SDK for JavaScript加载COG格式数据

ArcGIS JS 提供接口ImageryTileLayer可以直接加载。

【官网示例代码】ImageryTileLayer with COG

我们将GDAL计算得到的COG数据以静态文件形式封装成服务，用url进行访问。

核心代码：

const url = `http://127.0.0.1:8000/DemData/LocalData/ele-COG.tif`; //封装成自己的文件服务

view.graphics.removeAll();
const eleImageLayer = new ImageryTileLayer({ //使用ImageryTileLayer加载COG
    url: url, // 文件的url，可访问
    opacity: 1.0 //透明度
});
map.add(eleImageLayer);//添加到地图

完整代码：可直接使用。

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no">
    <title>ArcGIS JS - Elevation Data</title>
    <link rel="stylesheet" href="https://js.arcgis.com/4.22/esri/themes/light/main.css">
    <script src="https://js.arcgis.com/4.22/"></script>
    <style>
        html, body, #viewDiv {
            padding: 0;
            margin: 0;
            height: 100%;
            width: 100%;
        }
    </style>
</head>
<body>
    <div id="viewDiv">
        <button id="loadElevationData">Load Elevation Data</button>
        <div id="responseMessage"></div>
    </div>
    

    <script>
        require([
            "esri/Map",
            "esri/views/MapView",
            "esri/layers/ImageryTileLayer",
            "dojo/domReady!"
        ], function(Map, MapView, ImageryTileLayer) {
            // Create a map
            const map = new Map({
                basemap: "topo-vector"
            });

            // Create a view for the map
            const view = new MapView({
                container: "viewDiv",
                map: map,
                center: [0, 0],
                zoom: 2
            });

            // Function to zoom to the layer
            function zoomToLayer(layer) {
                view.whenLayerView(layer).then(function(layerView) {
                    view.goTo(layerView.fullExtent);
                });
            }

            // Button click event to fetch elevation data and add it to the map
            document.getElementById('loadElevationData').addEventListener('click', function() {
                const url = `http://127.0.0.1:8000/DemData/LocalData/ele-COG.tif`; 

                document.getElementById('responseMessage').textContent = "Elevation data loaded successfully." + '/n'+url;
                view.graphics.removeAll();
                const eleImageLayer = new ImageryTileLayer({
                    url: url,
                    opacity: 1.0
                });
                map.add(eleImageLayer);
                zoomToLayer(eleImageLayer);
                
            });
        });
    </script>
</body>
</html>

效果如下：