TWI

The TWI operator algorithm computes the Triangle Water Index from a given product.

The TWI results from the following equation:

TWI = (2.84 * (RE1 - RE2) / (G + S2)) + ((1.25 * (G - B) - (N - B)) / (N + 1.25 * G - 0.25 * B))

, where:

The bands are:

- B is the Blue band
- G is the Green band
- RE1 is the Red Edge 1 band
- RE2 is the Red Edge 2 band
- R is the Red band
- N is the NIR band
- S2 is the SWIR 2 band

TWI-Flags

Also the processor computes an additional flags band called 'twi_flags' with the following bit coding:

Bit Position	Description
Bit 0	The computed value for TWI is NAN or is Infinite
Bit 1	The computed value for TWI is less than -1 (minus one)
Bit 2	The computed value for TWI is greater than 1 (one)