ImageCollection 概览

ImageCollection 是图像的堆叠或序列。您可以通过将 Earth Engine 资产 ID 粘贴到 ImageCollection 构造函数中来加载 ImageCollection。您可以在数据目录中找到 ImageCollection ID。例如，如需加载 Sentinel-2 地表反射率集合，请执行以下操作：

Code Editor (JavaScript)

var sentinelCollection = ee.ImageCollection('COPERNICUS/S2_SR');

Python 设置

如需了解 Python API 以及如何使用 geemap 进行交互式开发，请参阅 Python 环境页面。

import ee
import geemap.core as geemap

Colab (Python)

sentinel_collection = ee.ImageCollection('COPERNICUS/S2_SR')

此集合包含公开目录中的每张 Sentinel-2 图像。有很多。 通常，您需要按此处或此处所示过滤合集。

除了使用 Earth Engine 集合 ID 加载 ImageCollection 之外，Earth Engine 还提供了创建图像集合的方法。构造函数 ee.ImageCollection() 或便捷方法 ee.ImageCollection.fromImages() 可根据图片列表创建图片集合。您还可以通过合并现有图库来创建新的图库。 例如：

Code Editor (JavaScript)

// Create arbitrary constant images.
var constant1 = ee.Image(1);
var constant2 = ee.Image(2);

// Create a collection by giving a list to the constructor.
var collectionFromConstructor = ee.ImageCollection([constant1, constant2]);
print('collectionFromConstructor: ', collectionFromConstructor);

// Create a collection with fromImages().
var collectionFromImages = ee.ImageCollection.fromImages(
  [ee.Image(3), ee.Image(4)]);
print('collectionFromImages: ', collectionFromImages);

// Merge two collections.
var mergedCollection = collectionFromConstructor.merge(collectionFromImages);
print('mergedCollection: ', mergedCollection);

// Create a toy FeatureCollection
var features = ee.FeatureCollection(
  [ee.Feature(null, {foo: 1}), ee.Feature(null, {foo: 2})]);

// Create an ImageCollection from the FeatureCollection
// by mapping a function over the FeatureCollection.
var images = features.map(function(feature) {
  return ee.Image(ee.Number(feature.get('foo')));
});

// Print the resultant collection.
print('Image collection: ', images);

Python 设置

如需了解 Python API 以及如何使用 geemap 进行交互式开发，请参阅 Python 环境页面。

import ee
import geemap.core as geemap

Colab (Python)

# Create arbitrary constant images.
constant_1 = ee.Image(1)
constant_2 = ee.Image(2)

# Create a collection by giving a list to the constructor.
collection_from_constructor = ee.ImageCollection([constant_1, constant_2])
display('Collection from constructor:', collection_from_constructor)

# Create a collection with fromImages().
collection_from_images = ee.ImageCollection.fromImages(
    [ee.Image(3), ee.Image(4)]
)
display('Collection from images:', collection_from_images)

# Merge two collections.
merged_collection = collection_from_constructor.merge(collection_from_images)
display('Merged collection:', merged_collection)

# Create a toy FeatureCollection
features = ee.FeatureCollection(
    [ee.Feature(None, {'foo': 1}), ee.Feature(None, {'foo': 2})]
)

# Create an ImageCollection from the FeatureCollection
# by mapping a function over the FeatureCollection.
images = features.map(lambda feature: ee.Image(ee.Number(feature.get('foo'))))

# Display the resultant collection.
display('Image collection:', images)

请注意，在此示例中，ImageCollection 是通过将返回 Image 的函数映射到 FeatureCollection 而创建的。如需详细了解映射，请参阅“映射 ImageCollection”部分。 如需详细了解地图项集合，请参阅 FeatureCollection 部分。

您还可以使用 Cloud Storage 中的 GeoTiff 创建 ImageCollection。例如：

Code Editor (JavaScript)

// All the GeoTiffs are in this folder.
var uriBase = 'gs://gcp-public-data-landsat/LC08/01/001/002/' +
    'LC08_L1GT_001002_20160817_20170322_01_T2/';

// List of URIs, one for each band.
var uris = ee.List([
  uriBase + 'LC08_L1GT_001002_20160817_20170322_01_T2_B2.TIF',
  uriBase + 'LC08_L1GT_001002_20160817_20170322_01_T2_B3.TIF',
  uriBase + 'LC08_L1GT_001002_20160817_20170322_01_T2_B4.TIF',
  uriBase + 'LC08_L1GT_001002_20160817_20170322_01_T2_B5.TIF',
]);

// Make a collection from the list of images.
var images = uris.map(ee.Image.loadGeoTIFF);
var collection = ee.ImageCollection(images);

// Get an RGB image from the collection of bands.
var rgb = collection.toBands().rename(['B2', 'B3', 'B4', 'B5']);
Map.centerObject(rgb);
Map.addLayer(rgb, {bands: ['B4', 'B3', 'B2'], min: 0, max: 20000}, 'rgb');

Python 设置

如需了解 Python API 以及如何使用 geemap 进行交互式开发，请参阅 Python 环境页面。

import ee
import geemap.core as geemap

Colab (Python)

# All the GeoTiffs are in this folder.
uri_base = (
    'gs://gcp-public-data-landsat/LC08/01/001/002/'
    + 'LC08_L1GT_001002_20160817_20170322_01_T2/'
)

# List of URIs, one for each band.
uris = ee.List([
    uri_base + 'LC08_L1GT_001002_20160817_20170322_01_T2_B2.TIF',
    uri_base + 'LC08_L1GT_001002_20160817_20170322_01_T2_B3.TIF',
    uri_base + 'LC08_L1GT_001002_20160817_20170322_01_T2_B4.TIF',
    uri_base + 'LC08_L1GT_001002_20160817_20170322_01_T2_B5.TIF',
])

# Make a collection from the list of images.
images = uris.map(lambda uri: ee.Image.loadGeoTIFF(uri))
collection = ee.ImageCollection(images)

# Get an RGB image from the collection of bands.
rgb = collection.toBands().rename(['B2', 'B3', 'B4', 'B5'])
m = geemap.Map()
m.center_object(rgb)
m.add_layer(rgb, {'bands': ['B4', 'B3', 'B2'], 'min': 0, 'max': 20000}, 'rgb')
m

详细了解如何从 Cloud GeoTiff 加载图片。