NDVI用于量化植被的绿色度，有助于了解植被密度和评估植物健康的变化。 NDVI按传统方式计算为红色(R)和近红外(NIR)归一化值:
NDVI=(NIR - R) / (NIR + R)
In Landsat 4-7, NDVI = (Band 4 – Band 3) / (Band 4 + Band 3).
In Landsat 8, NDVI = (Band 5 – Band 4) / (Band 5 + Band 4).
本文数据位Landsat8NDVI数据，基本信息如下：
| Attribute | Value |
|---|---|
| Long Name | Normalized Difference Vegetation Index |
| Short Name | LC8NDVI, LE7NDVI, LT5NDVI, or LT4NDVI |
| File Name | *_sr_ndvi.tif |
| Data Type | Signed 16-bit Integer |
| Units | Spectral Index (Band Ratio) |
| Valid Range | -10,000 — 10,000 |
| Fill Value | Collection 2: -1 |
