arcgis-imagery

ArcGIS 影像

在处理栅格影像、像素级操作、栅格函数、多维数据和定向影像查看器时使用此技能。

导入模式

ESM（npm）

import ImageryLayer from "@arcgis/core/layers/ImageryLayer.js";
import ImageryTileLayer from "@arcgis/core/layers/ImageryTileLayer.js";
import OrientedImageryLayer from "@arcgis/core/layers/OrientedImageryLayer.js";
import RasterFunction from "@arcgis/core/layers/support/RasterFunction.js";
import MosaicRule from "@arcgis/core/layers/support/MosaicRule.js";
import DimensionalDefinition from "@arcgis/core/layers/support/DimensionalDefinition.js";
import MultidimensionalSubset from "@arcgis/core/layers/support/MultidimensionalSubset.js";

CDN（动态导入）

const ImageryLayer = await $arcgis.import(
  "@arcgis/core/layers/ImageryLayer.js",
);
const ImageryTileLayer = await $arcgis.import(
  "@arcgis/core/layers/ImageryTileLayer.js",
);
const RasterFunction = await $arcgis.import(
  "@arcgis/core/layers/support/RasterFunction.js",
);

ImageryLayer

ImageryLayer 连接到 ArcGIS Image Services，以提供动态栅格数据。

基本 ImageryLayer

const imageryLayer = new ImageryLayer({
  url: "https://sampleserver6.arcgisonline.com/arcgis/rest/services/ScientificData/SeaTemperature/ImageServer",
});

map.add(imageryLayer);

带弹出窗口的 ImageryLayer

const imageryLayer = new ImageryLayer({
  url: "...",
  popupTemplate: {
    title: "Raster Value",
    content: "{Raster.ServicePixelValue}",
  },
});

ImageryLayer 的主要属性

属性	类型	描述
url	string	ImageServer REST 端点
format	string	输出格式（"jpgpng"、"tiff" 等）
bandIds	number[]	要显示的波段
rasterFunction	RasterFunction	服务端处理
mosaicRule	MosaicRule	栅格组合规则
pixelFilter	Function	客户端像素处理
renderingRule	object	客户端渲染规则（JSON）

ImageryTileLayer

ImageryTileLayer 可快速以切片方式访问影像，包括 Cloud-Optimized GeoTIFF（COG）。

基本 ImageryTileLayer

const imageryTileLayer = new ImageryTileLayer({
  url: "https://tiledimageservices.arcgis.com/...",
});

map.add(imageryTileLayer);

云优化 GeoTIFF（COG）

const imageryTileLayer = new ImageryTileLayer({
  url: "https://example.com/image.tif",
  title: "COG Layer",
});

栅格函数

应用栅格函数

// Hillshade
const hillshadeFunction = new RasterFunction({
  functionName: "Hillshade",
  functionArguments: {
    azimuth: 315,
    altitude: 45,
    zFactor: 1,
  },
});

imageryLayer.rasterFunction = hillshadeFunction;

常见栅格函数

// Stretch
const stretchFunction = new RasterFunction({
  functionName: "Stretch",
  functionArguments: {
    stretchType: 3,
    numberOfStandardDeviations: 2,
  },
});

// Colormap
const colormapFunction = new RasterFunction({
  functionName: "Colormap",
  functionArguments: {
    colormap: [
      [1, 255, 0, 0],
      [2, 0, 255, 0],
      [3, 0, 0, 255],
    ],
  },
});

// NDVI
const ndviFunction = new RasterFunction({
  functionName: "NDVI",
  functionArguments: {
    visibleBandID: 3,
    infraredBandID: 4,
  },
});

RasterFunction 属性

属性	类型	描述
functionName	string	栅格函数的名称
functionArguments	object	函数的参数
outputType	string	输出像素类型

常见函数名称： Hillshade、Stretch、Colormap、NDVI、GVITINDEX、SAVI、Pansharpening、Convolution、MLClassify

镶嵌规则

const mosaicRule = new MosaicRule({
  mosaicMethod: "center", // "center", "northwest", "nadir", "lock-raster", "by-attribute"
  mosaicOperator: "first", // "first", "last", "min", "max", "mean", "sum", "blend"
  lockRasterIds: [1, 2, 3], // Lock to specific rasters
  multidimensionalDefinition: [], // For multidimensional data
});

imageryLayer.mosaicRule = mosaicRule;

多维数据

DimensionalDefinition

// Define dimensions (depth, time, etc.)
const dimInfo = [];

// Depth dimension
dimInfo.push(
  new DimensionalDefinition({
    dimensionName: "StdZ",
    values: [0],
    isSlice: true,
  }),
);

// Time dimension
dimInfo.push(
  new DimensionalDefinition({
    dimensionName: "StdTime",
    values: [1396828800000],
    isSlice: true,
  }),
);

const mosaicRule = new MosaicRule({
  multidimensionalDefinition: dimInfo,
});

const layer = new ImageryLayer({
  url: "...",
  mosaicRule: mosaicRule,
});

访问多维信息

await imageryLayer.load();

const dimensions = imageryLayer.multidimensionalInfo.dimensions;
dimensions.forEach((dim) => {
  console.log("Dimension:", dim.name);
  console.log("Values:", dim.values);
  console.log("Unit:", dim.unit);
});

多维 ImageryTileLayer

const layer = new ImageryTileLayer({
  url: "...",
  multidimensionalSubset: {
    dimensions: [
      {
        name: "StdTime",
        values: [
          /* epoch ms */
        ],
      },
      {
        name: "StdZ",
        values: [
          /* depth values */
        ],
      },
    ],
  },
  multidimensionalDefinition: [
    new DimensionalDefinition({
      dimensionName: "StdTime",
      values: [1609459200000],
    }),
  ],
});

常见维度名称： StdTime、StdZ、StdPlev、StdDepth

像素过滤

自定义像素过滤器

const imageryLayer = new ImageryLayer({
  url: "...",
  pixelFilter: processPixels,
});

function processPixels(pixelData) {
  if (!pixelData || !pixelData.pixelBlock) return;

  const pixelBlock = pixelData.pixelBlock;
  const pixels = pixelBlock.pixels;
  let mask = pixelBlock.mask;
  const numPixels = pixelBlock.width * pixelBlock.height;

  const minVal = pixelBlock.statistics[0].minValue;
  const maxVal = pixelBlock.statistics[0].maxValue;
  const factor = 255 / (maxVal - minVal);

  const band = pixels[0];
  const rBand = new Uint8Array(numPixels);
  const gBand = new Uint8Array(numPixels);
  const bBand = new Uint8Array(numPixels);

  if (!mask) {
    mask = new Uint8Array(numPixels);
    mask.fill(1);
    pixelBlock.mask = mask;
  }

  for (let i = 0; i < numPixels; i++) {
    if (mask[i] === 0) continue;
    const normalized = (band[i] - minVal) * factor;
    rBand[i] = normalized;
    gBand[i] = 0;
    bBand[i] = 255 - normalized;
  }

  pixelData.pixelBlock.pixels = [rBand, gBand, bBand];
  pixelData.pixelBlock.statistics = null;
  pixelData.pixelBlock.pixelType = "u8";
}

按值遮罩像素

let minThreshold = 0;
let maxThreshold = 100;

function maskPixels(pixelData) {
  if (!pixelData || !pixelData.pixelBlock) return;

  const pixelBlock = pixelData.pixelBlock;
  const pixels = pixelBlock.pixels[0];
  let mask = pixelBlock.mask;

  if (!mask) {
    mask = new Uint8Array(pixels.length);
    mask.fill(1);
    pixelBlock.mask = mask;
  }

  for (let i = 0; i < pixels.length; i++) {
    mask[i] = pixels[i] >= minThreshold && pixels[i] <= maxThreshold ? 1 : 0;
  }
}

// Update thresholds and redraw
function updateThresholds(min, max) {
  minThreshold = min;
  maxThreshold = max;
  imageryLayer.redraw();
}

PixelBlock 结构

属性	类型	描述
pixels	TypedArray[]	每个波段对应一个数组
mask	Uint8Array	0 = 透明，1 = 不透明
statistics	object[]	每个波段的 { minValue, maxValue }
width	number	像素块宽度
height	number	像素块高度
pixelType	string	"u8"、"u16"、"u32"、"s16"、"s32"、"f32"、"f64"

波段组合

// Select specific bands
imageryLayer.bandIds = [4, 3, 2]; // NIR, Red, Green (False color)

// Common band combinations
// Natural color: [1, 2, 3] (R, G, B)
// False color: [4, 3, 2] (NIR, R, G)
// SWIR: [7, 5, 4] (SWIR, NIR, R)

Identify（查询像素值）

view.on("click", async (event) => {
  const result = await imageryLayer.identify({
    geometry: event.mapPoint,
    returnGeometry: false,
    returnCatalogItems: true,
  });

  console.log("Pixel value:", result.value);
  console.log("Catalog items:", result.catalogItems);
});

栅格统计信息

await imageryLayer.load();

const stats = imageryLayer.serviceRasterInfo.statistics;
console.log("Min:", stats[0].min);
console.log("Max:", stats[0].max);
console.log("Mean:", stats[0].avg);
console.log("StdDev:", stats[0].stddev);

定向影像

OrientedImageryLayer

const oiLayer = new OrientedImageryLayer({
  url: "https://services.arcgis.com/.../FeatureServer/0",
});

map.add(oiLayer);

OrientedImageryViewer 微件

import OrientedImageryViewer from "@arcgis/core/widgets/OrientedImageryViewer.js";

const oiViewer = new OrientedImageryViewer({
  view: view,
});

view.ui.add(oiViewer, "top-right");

影像组件

组件	用途
arcgis-oriented-imagery-viewer	查看和浏览定向影像
arcgis-video-player	播放来自视频服务的视频流

常见问题

1. 像素滤镜性能：复杂的像素滤镜会在每次渲染时运行，请优化循环并尽量减少内存分配。

2. 波段数组索引：服务中的波段 ID 从 1 开始，而 bandIds 数组中的索引从 0 开始。

3. 坐标系：可能需要对影像进行重投影，使其与视图的空间参考保持一致。

4. 大尺寸影像的内存占用：大型数据集请使用 ImageryTileLayer，它会自动切片。

5. 像素类型转换：在像素滤镜中更改 pixelType 时请谨慎，不匹配会导致图像失真。

6. 更改滤镜后重绘：更改 pixelFilter 中使用的外部变量后，调用 imageryLayer.redraw()。

参考示例

• layers-imagerylayer — 基本的 ImageryLayer
• layers-imagery-pixelvalues — 查询像素值
• layers-imagery-rasterfunction — 栅格函数处理
• layers-imagery-multidimensional — 多维影像
• layers-imagerytilelayer — ImageryTileLayer
• layers-imagerytilelayer-cog — 云优化 GeoTIFF
• layers-imagery-renderer — 影像渲染器
• layers-imagery-clientside — 客户端影像处理
• layers-orientedimagerylayer — 定向影像

相关技能

• arcgis-time-animation — 感知时间的影像动画
• arcgis-layers — 常见图层模式
• arcgis-smart-mapping — 自动生成的渲染器
• arcgis-custom-rendering — 自定义切片图层渲染