JavaScript ArcGIS RasterFunction用法及代码示例

AMD: require(["esri/layers/support/RasterFunction"], (RasterFunction) => { /* code goes here */ });

ESM: import RasterFunction from "@arcgis/core/layers/support/RasterFunction.js";

类： esri/layers/support/RasterFunction

继承: RasterFunction > Accessor

自从：ArcGIS JavaScript 4.0 Map SDK

栅格函数指定对影像服务进行的处理。它们允许马赛克图像服务提供动态马赛克图像，并且可用于通过应用图像增强和图像代数等处理操作来增强马赛克图像产品。有关函数及其参数的列表，请参阅raster functions。下图显示了使用两个链接的客户端栅格函数渲染的土地覆盖ImageryLayer，用于重新分类像素值(重新映射)并为每个像素分配新颜色(颜色图)。

链接栅格函数是通过将 functionArguments 属性中的栅格参数设置为另一个定义的栅格函数来完成的。请参阅下面有关将重映射栅格函数与颜色图链接的示例。

let remapRF = new RasterFunction();
remapRF.functionName = "Remap";
remapRF.functionArguments = {
  InputRanges: [-3,10,11,37], // remap pixels with values -3 to 10 to now have value of 1
  OutputValues: [1,2],        // remap pixel values from 11 to 37 to have a value of 2
  Raster: "$$"  // Apply remap to the image service
};
remapRF.outputPixelType = "u8";

let colorRF = new RasterFunction();
colorRF.functionName = "Colormap";
colorRF.functionArguments = {
  Colormap: [
    [1, 255, 0, 0],  // Symbolize pixels with value of 1 using red color
    [2, 0, 255, 0]   // Symbolize pixels with value of 2 using green color
  ],
  Raster : remapRF  // Apply Colormap to output raster from the remap rasterFunction
};

imageLayer.rasterFunction = colorRF;