| IPVI Algorithm Specification | |
The Infrared Percentage Vegetation Index
algorithm was first described by Crippen (1990).
Crippen found that the subtraction of the red in the numerator was irrelevant, and proposed this index as a way of improving calculation speed.
It is restricted to values between 0 and 1, which eliminates the need for storing a sign for the vegetation index values.
It also eliminates the conceptual strangeness of negative values for vegetation indices.
The IPVI results from the following equation:
IPVI = (IR_factor * near_IR) / (IR_factor * near_IR + red_factor * red)
or:
IPVI = 1/2 * (NDVI + 1)
where: NDVI = (IR_factor * near_IR - red_factor * red) / (IR_factor * near_IR + red_factor * red)
Conclussions:
- IPVI is functionally equivalent to NDVI and RVI, but it only ranges in value from 0.0 - 1.0
- IPVI eliminates one mathematical operation per image pixel which is important for the rapid processing of large amounts of data.
Also the processor computes an additional flags band called 'ipvi_flags' with the following bit coding:
| Bit Position | Description |
|---|---|
| Bit 0 | The computed value for IPVI is NAN or is Infinite |
| Bit 1 | The computed value for IPVI is less than 0 (zero) |
| Bit 2 | The computed value for IPVI is greater than 1 (one) |