Ringkasan ImageCollection

ImageCollection adalah tumpukan atau urutan gambar. ImageCollection dapat dimuat dengan menempelkan ID aset Earth Engine ke konstruktor ImageCollection. Anda dapat menemukan ID ImageCollection di katalog data. Misalnya, untuk memuat koleksi pantulan permukaan Sentinel-2:

Editor Kode (JavaScript)Colab (Python)
var sentinelCollection = ee.ImageCollection('COPERNICUS/S2_SR');

Lihat halaman Lingkungan Python untuk mengetahui informasi tentang Python API dan penggunaan geemap untuk pengembangan interaktif.

import ee
import geemap.core as geemap
 
sentinel_collection = ee.ImageCollection('COPERNICUS/S2_SR')

Koleksi ini berisi setiap gambar Sentinel-2 dalam katalog publik. Ada banyak. Biasanya, Anda ingin memfilter koleksi seperti yang ditunjukkan di sini atau di sini.

Selain memuat ImageCollection menggunakan ID koleksi Earth Engine, Earth Engine memiliki metode untuk membuat koleksi gambar. Konstruktor ee.ImageCollection() atau metode praktis ee.ImageCollection.fromImages() membuat koleksi gambar dari daftar gambar. Anda juga dapat membuat koleksi gambar baru dengan menggabungkan koleksi yang ada. Contoh:

Editor Kode (JavaScript)Colab (Python)
// 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);

Lihat halaman Lingkungan Python untuk mengetahui informasi tentang Python API dan penggunaan geemap untuk pengembangan interaktif.

import ee
import geemap.core as geemap
 
# 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)

Perhatikan bahwa dalam contoh ini, ImageCollection dibuat dengan memetakan fungsi yang menampilkan Image melalui FeatureCollection. Pelajari pemetaan lebih lanjut di bagian Pemetaan di bagian ImageCollection. Pelajari koleksi fitur lebih lanjut dari bagian FeatureCollection.

Anda juga dapat membuat ImageCollection dari GeoTiff di Cloud Storage. Contoh:

Editor Kode (JavaScript)Colab (Python)
// 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');

Lihat halaman Lingkungan Python untuk mengetahui informasi tentang Python API dan penggunaan geemap untuk pengembangan interaktif.

import ee
import geemap.core as geemap
 
# 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

Pelajari lebih lanjut cara memuat gambar dari Cloud GeoTiff.