| TNDVI Algorithm Specification | |
The Transformed Normalized Difference Vegetation Index
algorithm indicates a relation between the amount of green biomass that is found in a pixel. (Senseman et.al. 1996)
Transformed Normalised Difference Vegetation index (TNDVI) is the square root of the NDVI.
It has higher coefficient of determination for the same variable and this is the difference between TNDVI and NDVI.
The formula of TNDVI has always positive values and the variances of the ratio are proportional to mean values.
The TNDVI results from the following equation:
TNDVI = sqrt( (IR_factor * near_IR - red_factor * red) / (IR_factor * near_IR + red_factor * red) + 0.5)
Also the processor computes an additional flags band called 'tndvi_flags' with the following bit coding:
| Bit Position | Description |
|---|---|
| Bit 0 | The computed value for TNDVI is NAN or is Infinite |
| Bit 1 | The computed value for TNDVI is less than 0 (zero) |
| Bit 2 | The computed value for TNDVI is greater than 1.23 (one point two three) |