Skip to content

The researcher’s complete guide to NDVI and PRI

NDVI and PRI: theory, methods, and application

Modern technology makes it possible to sample spectral vegetation indices such as NDVI and PRI across a range of scales both in space and in time, from satellites sampling the entire earth’s surface to handheld small sensors that measure individual plants or even leaves.

Figure 1: NDVI is sensitive to the amount of vegetation cover that is present across the earth’s surface (source: low res map obtained from an earth orbiting satellite)

What are NDVI and PRI?

NDVI and PRI are both spectral vegetation indices derived from measurements of relatively narrow wavelengths of reflected light (10 to 50 nanometers) in the electromagnetic spectrum. This is useful for measuring various properties in plant canopies. NDVI stands for the Normalized Difference Vegetation Index and PRI stands for the Photochemical Reflectance Index.

image of SRS spectral reflectance sensor to measure NDVI and PRI | METER Environment
The METER SRS sensor measures both NDVI and PRI and works with ZENTRA Cloud for data visualization in near-real time.

There are many types of spectral vegetation indices, however, this article and the webinar below focus on the theory, methods and application of NDVI and PRI as they are two of the most commonly used (see webinar).


NDVI is especially useful for measuring plant canopy structural properties such as leaf area index, light interception and even biomass and growth, whereas PRI is more useful for getting at functional properties of plant canopies such as light use efficiency. Recent literature shows that PRI is also useful for measuring foliar pigments.

Understanding canopy radiation interactions 

To understand where NDVI and PRI come from, it’s important to learn about canopy-radiation interactions. There are three primary fates for electromagnetic radiation as it interacts with plant canopies.

Read more—>

No comments yet

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Share to...