WRI 참고: WRI는 FORMA 알림 업데이트를 중단하기로 결정했습니다. 목표는 Global Forest Watch 사용자 환경을 간소화하고 중복을 줄이는 것이었습니다.
Terra-i와 GLAD가 더 자주 사용되는 것으로 확인되었습니다.
또한 GLAD를 표준으로 사용하여 Terra-i가 전 세계적으로 FORMA보다 성능이 우수함을 확인했습니다.
FORMA 알림은 NDVI (정규 식생 지수)와 FIRMS(자원 관리 시스템용 화재 정보)라는 두 가지 MODIS 제품을 조합하여 감지됩니다. NDVI 업데이트는 16일마다 처리되고 화재 업데이트는 매일 처리됩니다. 모델은 각 생태 그룹에 대해 개별적으로 개발되어 두 입력을 벌채 지역과 연결하며, Hansen 연간 나무 덮개 손실 데이터를 사용하여 모델을 학습시킵니다. 경고로 간주되는 최소 기준점은 픽셀의 25% 가 지워진 경우입니다. 하지만 오탐을 최소화하기 위해 기준점은 ecogroup에 따라 다릅니다.
다음은 FORMA 데이터 세트를 간략하게 소개하는 예시 스크립트입니다.
이 ImageCollection의 이미지에는 NTT를 계산하는 데 사용되는 '역전된 보정 t-통계'와 FORMA가 갈변을 측정하는 데 사용하는 MODIS NDVI에서 파생된 식물 색상 지수가 포함됩니다. 이 ImageCollection의 다양한 기간에 합계 리듀서를 사용하면 'NTT' 이미지가 생성됩니다.
'ecogroup'으로 인해 이미지가 손상되었습니다.
대역
픽셀 크기 250미터
대역
이름
최소
최대
픽셀 크기
설명
tstat_r
0*
25.41*
미터
수정된 역전된 값, 즉 (max(0,-t_stat)), t-통계입니다.
* 예상 최솟값 또는 최댓값
이미지 속성
이미지 속성
이름
유형
설명
년
INT
데이터 세트에 포함된 가장 최근 데이터의 연도
격주
INT
1년 중 2주 (16일) 간격으로 반복되는 기간
ecogroup_id
문자열
연결된 ecogroup의 ID
이용약관
이용약관
FORMA 데이터 세트는 사용 또는 배포에 제한이 없습니다. WRI는 사용자가 적절한 저작자 표시를 제공하고 해당되는 경우 WRI와 GFW를 데이터 소스로 식별하도록 요청합니다.
WRI 참고: WRI는 FORMA 알림 업데이트를 중단하기로 결정했습니다. 목표는 Global Forest Watch 사용자 환경을 간소화하고 중복을 줄이는 것이었습니다. Terra-i와 GLAD가 더 자주 사용되는 것으로 확인되었습니다. 또한 GLAD를 표준으로 사용하여 Terra-i가 전 세계적으로 FORMA보다 성능이 우수함을 확인했습니다. FORMA 알림이 감지됨 …
[null,null,[],[[["\u003cp\u003eThe FORMA dataset provides MODIS-based vegetation change alerts, specifically "reversed rectified t-statistics" used to measure browning, with a resolution of 250 meters.\u003c/p\u003e\n"],["\u003cp\u003eWRI has discontinued updating FORMA alerts, recommending Terra-i and GLAD as preferred alternatives due to their performance and user experience.\u003c/p\u003e\n"],["\u003cp\u003eFORMA alerts were generated using NDVI and FIRMS data, trained with Hansen tree cover loss data, and triggered when 25% or more of a pixel was cleared.\u003c/p\u003e\n"],["\u003cp\u003eThe dataset is organized by ecogroups and includes bi-weekly periods for the years 2012 to 2019.\u003c/p\u003e\n"],["\u003cp\u003eThe FORMA datasets are available for use without restriction, but attribution to WRI and GFW is requested.\u003c/p\u003e\n"]]],["The WRI/GFW/FORMA vegetation t-statistics dataset, provided by the World Resources Institute/Global Forest Watch, spans from 2012 to 2019. It uses MODIS-derived NDVI and FIRMS data to detect forest clearing alerts, updating NDVI every 16 days and fire data daily. Alerts are generated when at least 25% of a pixel is cleared. The dataset, which is no longer updated, provides reversed rectified t-statistics used to measure vegetation browning and is broken down by ecogroup with 250-meter pixel size.\n"],null,["# FORMA Vegetation T-Statistics\n\nDataset Availability\n: 2012-01-01T00:00:00Z--2019-04-23T00:00:00Z\n\nDataset Provider\n:\n\n\n [World Resources Institute / Global Forest Watch](https://www.globalforestwatch.org/)\n\nTags\n:\n[daily](/earth-engine/datasets/tags/daily) [deforestation](/earth-engine/datasets/tags/deforestation) [forest](/earth-engine/datasets/tags/forest) [forest-biomass](/earth-engine/datasets/tags/forest-biomass) [forma](/earth-engine/datasets/tags/forma) [gfw](/earth-engine/datasets/tags/gfw) [modis](/earth-engine/datasets/tags/modis) [monitoring](/earth-engine/datasets/tags/monitoring) [wri](/earth-engine/datasets/tags/wri) \n\n#### Description\n\n**NOTE from WRI** : WRI decided to stop updating FORMA alerts. The goal was\nto simplify the [Global Forest Watch](https://www.globalforestwatch.org)\nuser experience and reduce redundancy.\nWe found that [Terra-i](http://www.terra-i.org/terra-i.html) and\n[GLAD](https://glad-forest-alert.appspot.com/) were more frequently used.\nMoreover, using GLAD as a standard, found that Terra-i outperformed\nFORMA globally.\n\nFORMA alerts are detected using a combination of two MODIS\nproducts: NDVI (Normalized Difference Vegetation Index) and FIRMS\n(Fires Information for Resource Management System). NDVI updates are\nprocessed every 16 days, while fire updates are processed daily. Models\nare developed individually for each ecogroup to relate the two inputs to\nthe area of clearing, using the Hansen annual tree cover loss data to train\nthe model. The minimum threshold to qualify as an alert is 25% of the pixel\ncleared, though thresholds vary by ecogroup to minimize false positives.\nHere is an [example script](https://code.earthengine.google.com/f29b1e4360f3fc36847bd789ceeb20f6)\nfor a quick introduction to the FORMA datasets.\n\nThe images in this ImageCollection contain the \"reversed rectified\nt-statistics\" used in calculating NTT, the vegetation color index derived\nfrom MODIS NDVI that FORMA uses to measure browning. Using a sum reducer on\nover various date ranges in this ImageCollection produces an \"NTT\" image.\n\nThe images are broken by \"ecogroup\".\n\n### Bands\n\n\n**Pixel Size**\n\n250 meters\n\n**Bands**\n\n| Name | Min | Max | Pixel Size | Description |\n|-----------|-----|---------|------------|--------------------------------------------------------|\n| `tstat_r` | 0\\* | 25.41\\* | meters | Reversed rectified, ie (max(0,-t_stat)), t-statistics. |\n\n\\* estimated min or max value\n\n### Image Properties\n\n**Image Properties**\n\n| Name | Type | Description |\n|-------------|--------|------------------------------------------------------|\n| year | INT | Year of the most recent data included in the dataset |\n| biweekly | INT | The biweekly (every 16 days) period of the year |\n| ecogroup_id | STRING | ID of associated ecogroup |\n\n### Terms of Use\n\n**Terms of Use**\n\nThe FORMA datasets are available without restriction\non use or distribution. WRI does request that the\nuser give proper attribution and identify WRI and GFW, where applicable,\nas the source of the data.\n\n### Explore with Earth Engine\n\n| **Important:** Earth Engine is a platform for petabyte-scale scientific analysis and visualization of geospatial datasets, both for public benefit and for business and government users. Earth Engine is free to use for research, education, and nonprofit use. To get started, please [register for Earth Engine access.](https://console.cloud.google.com/earth-engine)\n\n### Code Editor (JavaScript)\n\n```javascript\nvar dataset = ee.ImageCollection('WRI/GFW/FORMA/vegetation_tstats')\n .filter(ee.Filter.date('2018-07-01', '2018-07-15'));\nvar tstat = dataset.select('tstat_r');\nvar visParams = {\n min: 0,\n max: 1,\n};\nMap.setCenter(26, -8, 3);\nMap.addLayer(tstat, visParams, 'Reversed rectified t-statistics');\n```\n[Open in Code Editor](https://code.earthengine.google.com/?scriptPath=Examples:Datasets/WRI/WRI_GFW_FORMA_vegetation_tstats) \n[FORMA Vegetation T-Statistics](/earth-engine/datasets/catalog/WRI_GFW_FORMA_vegetation_tstats) \nNOTE from WRI: WRI decided to stop updating FORMA alerts. The goal was to simplify the Global Forest Watch user experience and reduce redundancy. We found that Terra-i and GLAD were more frequently used. Moreover, using GLAD as a standard, found that Terra-i outperformed FORMA globally. FORMA alerts are detected ... \nWRI/GFW/FORMA/vegetation_tstats, daily,deforestation,forest,forest-biomass,forma,gfw,modis,monitoring,wri \n2012-01-01T00:00:00Z/2019-04-23T00:00:00Z \n-50 -120 40 180 \nGoogle Earth Engine \nhttps://developers.google.com/earth-engine/datasets\n\n- [](https://doi.org/https://www.globalforestwatch.org/)\n- [](https://doi.org/https://developers.google.com/earth-engine/datasets/catalog/WRI_GFW_FORMA_vegetation_tstats)"]]
