# NDBI formula for Landsat 8

The formula for NDBI for landsat 8 is (NIR-swir)/(NIR+swir). I am confused if it is (Band5-band6)/(Band5+band6) OR (Band5-band7)/(Band5+band7)?

(For Landsat 5TM, NDBI formula is (Band5-Band4)/(Band5+Band4), and wavelength of band 5 is between 1.55-1.75. So, by refering the wavelength, I am guessing, below formula to be correct for Landsat 8.

(Band5-band6)/(Band5+band6), but I want to be sure. Please help me clear my confusion.

## 2 Answers

I am not 100% familiar with the NDBI Index, but found an article here: https://www.researchgate.net/publication/273886729_Built-up_area_extraction_using_Landsat_8_OLI_imagery

Specifically on Page 14 that describes the NDBI as:

NDBI = (Band 5 - Band 4) / (Band 5 + Band 4)

Which is the original equation.

In order to get the NDBI for the Landsat 8 the author combines the Bands 6 and 7 and Bands 10 and 11 in a PCA.

NDBI = (PCA B6,7 + PCA 10,11) - Band 5 / (PCA B6,7 + PCA 10,11) + Band 5

Another article Here describes the NDBI as

NDBI = (B6 - B5) / (B6 + B5)

Another article Here describes the SWIR for use in the NDBI as 1.57 - 1.65um. Which according to the Landsat Website, puts this as Band 6. Which corroborates the B6-B5 / B6+B5 equations.

• Cool if this is the answer you needed, please click the little green tick to show the question is answered and closed. – Keagan Allan Apr 3 '18 at 8:49

For Landsat 8 you can follow this equation below

NDBI = Band 7 MIR or SWIR - Band 5 NIR / Band 7 + Band 5