NDBI简介及计算

Normalized Difference Built-up Index (NDBI)

用来分析建成区的指数有很多：

Normalized Difference Built-up Index (NDBI)

Built-up Index (BU)

Urban Index (UI)

Index-based Built-up Index (IBI)

Enhanced Built-up and Bareness Index (EBBI)

这些是最常用的，它们有各自的计算方法. 建成区和裸土在SWIR(短波红外)波段比在NIR(近红外)波段反射更多一些. 水体在红外波段几乎没有反射。

For better result, you can use Built-up Index (BU). Build-up Index is the index for analysis of urban pattern using NDBI and NDVI. Built-up index is the binary image with only higher positive value indicates built-up and barren thus, allows BU to map the built-up area automatically.

BU = NDBI - NDVI

NDBI 计算：

NDBI = (SWIR – NIR) / (SWIR + NIR)

For Landsat 7 data, NDBI = (Band 5 – Band 4) / (Band 5 + Band 4)

For Landsat 8 data, NDBI = (Band 6 – Band 5) / (Band 6 + Band 5)

Also, the Normalize Difference Build-up Index value lies between -1 to +1.

NDBI 负值代表水体，高值代表 建成区，植被的NDBI值比较低。

ENVI中Band Math计算公式：float(b5-b4)/float(b5+b4)   或者 (float(b5)-float(b4))/(float(b5)+float(b4))