{"id":54,"date":"2022-05-15T10:00:57","date_gmt":"2022-05-15T03:00:57","guid":{"rendered":"https:\/\/opengis.vn\/?p=54"},"modified":"2024-03-28T09:18:39","modified_gmt":"2024-03-28T02:18:39","slug":"gee-co-ban-huong-dan-them-mot-tap-anh-trong-google-earth-engine","status":"publish","type":"post","link":"https:\/\/opengis.vn\/en\/blog\/gee-co-ban-huong-dan-them-mot-tap-anh-trong-google-earth-engine\/","title":{"rendered":"[GEE C\u01a1 b\u1ea3n #1] H\u01b0\u1edbng d\u1eabn th\u00eam m\u1ed9t t\u1eadp \u1ea3nh trong Google Earth Engine"},"content":{"rendered":"

English version here<\/a>.<\/p>\n

M\u1edf \u0111\u1ea7u<\/h2>\n

Trong tr\u00ecnh duy\u1ec7t web, v\u00e0o trang ch\u1ee7 Google Earth Engine: https:\/\/earthengine.google.com\/<\/a> Click v\u00e0o Datasets \u1edf g\u00f3c tr\u00ean b\u00ean ph\u1ea3i.<\/p>\n

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Trong data catalog c\u1ee7a GEE ch\u00fang ta c\u00f3 r\u1ea5t nhi\u1ec1u lo\u1ea1i d\u1eef li\u1ec7u, h\u00f4m nay ch\u00fang ta s\u1ebd l\u00e0m vi\u1ec7c v\u1edbi d\u1eef li\u1ec7u Landsat.<\/p>\n

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Click v\u00e0o k\u00fd hi\u1ec7u cu\u1ed1i d\u00f2ng code n\u00e0y s\u1ebd d\u1eabn ch\u00fang ta t\u1edbi script m\u1eabu trong https:\/\/code.earthengine.google.com\/<\/a>, \u0111\u01b0\u1ee3c vi\u1ebft b\u1eb1ng ng\u00f4n ng\u1eef Javascript:<\/p>\n

\"image\"<\/p>\n

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N\u1ebfu b\u1ea1n ch\u01b0a \u0111\u0103ng nh\u1eadp, ch\u00fang ta s\u1ebd ph\u1ea3i \u0111\u0103ng nh\u1eadp b\u1eb1ng t\u00e0i kho\u1ea3n google.<\/p>\n

Gi\u1ea3i th\u00edch c\u00e1c d\u00f2ng code<\/h2>\n

D\u00f2ng code \u0111\u1ea7u ti\u00ean: s\u1eed d\u1ee5ng t\u1eeb kh\u00f3a var t\u1ea1o bi\u1ebfn dataset, bi\u1ebfn n\u00e0y s\u1ebd ch\u1ee9a t\u1eadp h\u1ee3p \u1ea3nh Landsat 8 Collection 2 Tier 1 calibrated top-of-atmosphere (TOA) reflectance c\u1ee7a GEE.<\/p>\n

var dataset = ee.ImageCollection('LANDSAT\/LC08\/C01\/T1_TOA')\n<\/code><\/pre>\n
(T\u1eadp h\u1ee3p \u1ea3nh l\u00e0 m\u1ed9t nh\u00f3m c\u00e1c \u1ea3nh c\u00f9ng lo\u1ea1i trong Earth Engine. V\u00ed d\u1ee5 nh\u01b0, t\u1ea5t c\u1ea3 \u1ea3nh Landsat 8 trong GEE l\u00e0 m\u1ed9t t\u1eadp h\u1ee3p \u1ea3nh)<\/p>\n
D\u00f2ng code th\u1ee9 2 l\u1ecdc c\u00e1c \u1ea3nh trong th\u1eddi gian t\u1eeb 1\/1\/2017 \u0111\u1ebfn 31\/12\/017<\/p>\n
                  .filterDate('2017-01-01', '2017-12-31');<\/code><\/pre>\n
D\u00f2ng code th\u1ee9 3 t\u1ea1o bi\u1ebfn trueColor432 ch\u1ee9a c\u00e1c k\u00eanh m\u00e0u th\u1ef1c 4, 3 v\u00e0 2.<\/p>\n
var trueColor432 = dataset.select(['B4', 'B3', 'B2']);<\/code><\/pre>\n
D\u00f2ng code th\u1ee9 4 t\u1ea1o bi\u1ebfn trueColor432Vis x\u00e1c \u0111\u1ecbnh gi\u00e1 tr\u1ecb max l\u00e0 0.4 v\u00e0 min l\u00e0 0.0<\/p>\n
var trueColor432Vis = {\n  min: 0.0,\n  max: 0.4,\n};<\/code><\/pre>\n
D\u00f2ng code th\u1ee9 5: H\u00e0m Map.setCenter cho GEE bi\u1ebft n\u00ean xem b\u1ea3n \u0111\u1ed3 \u1edf t\u1ecda \u0111\u1ed9 n\u00e0o, v\u1edbi m\u1ee9c \u0111\u1ed9 zoom n\u00e0o.<\/p>\n
Map.setCenter(6.746, 46.529, 6);<\/code><\/pre>\n
T\u1ea1i thanh c\u00f4ng c\u1ee5 ph\u00eda tr\u00ean b\u00ean tr\u00e1i, chuy\u1ec3n t\u1eeb tab Scripts sang tab Docs. G\u00f5 Map.setCenter\u00a0 v\u00e0o ph\u1ea7n t\u00ecm ki\u1ebfm\/search bar c\u1ee7a Docs \u2192 Kho\u1ea3ng gi\u1edbi h\u1ea1n ph\u00f3ng to thu nh\u1ecf l\u00e0 0 \u0111\u1ebfn 24.<\/p>\n
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Ch\u00fang ta thay \u0111\u1ed5i tham s\u1ed1 th\u1ee9 3 c\u1ee7a h\u00e0m, s\u1ed1 nh\u1ecf h\u01a1n \u0111\u1ec3 thu nh\u1ecf\/zoom out, s\u1ed1 l\u1edbn h\u01a1n \u0111\u1ec3 ph\u00f3ng to\/zoom in.<\/p>\n
T\u1ea5t c\u1ea3 c\u00e1c tham s\u1ed1 \u0111\u1ec1u thay \u0111\u1ed5i \u0111\u01b0\u1ee3c, c\u00e1c b\u1ea1n h\u00e3y v\u00e0o ph\u1ea7n Docs \u0111\u1ecdc th\u00eam v\u1ec1 c\u00e1c h\u00e0m \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng v\u00e0 th\u1eed thay \u0111\u1ed5i c\u00e1c tham s\u1ed1 nh\u00e9.<\/p>\n
D\u00f2ng l\u1ec7nh cu\u1ed1i s\u1eed d\u1ee5ng h\u00e0m Map.addLayer s\u1ebd gi\u00fap \u0111\u01b0a t\u1eadp \u1ea3nh Landsat v\u1edbi k\u00eanh 4, 3, 2 v\u00e0o c\u1eeda s\u1ed5 b\u1ea3n \u0111\u1ed3, v\u00e0 gi\u00e1 tr\u1ecb hi\u1ec3n th\u1ecb s\u1ebd gi\u1edbi h\u1ea1n t\u1eeb min = 0.0 \u0111\u1ebfn max = 0.4.<\/p>\n
Map.addLayer(trueColor432, trueColor432Vis, 'True Color (432)');<\/code><\/pre>\n
L\u1edbp d\u1eef li\u1ec7u True Color (432) s\u1ebd \u0111\u01b0\u1ee3c th\u00eam v\u00e0o map view.<\/p>\n
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R\u00fat g\u1ecdn code<\/h2>\n
Thay v\u00ec t\u1ea1o nhi\u1ec1u bi\u1ebfn kh\u00e1c nhau, ch\u00fang ta c\u00f3 th\u1ec3 thu g\u1ecdn \u0111o\u1ea1n script n\u00e0y th\u00e0nh:<\/p>\n
var dataset = ee.ImageCollection('LANDSAT\/LC08\/C01\/T1_TOA')\n                  .filterDate('2017-01-01', '2017-12-31');\n\nMap.setCenter(6.746, 46.529, 6);\nMap.addLayer(dataset, { min:0.0, max: 0.4, bands: 'B4,B3,B2' }, 'True Color (432)');<\/code><\/pre>\n
C\u00e1c b\u1ea1n c\u0169ng c\u00f3 th\u1ec3 th\u1eed v\u1edbi nh\u1eefng d\u1eef li\u1ec7u kh\u00e1c m\u00e0 GEE c\u00f3 s\u1eb5n nh\u00e9.<\/p>\n
Video h\u01b0\u1edbng d\u1eabn th\u00eam t\u1eadp \u1ea3nh trong Google Earth Engine:<\/h2>\n