Skip to main content

How to convert your multispectral data to NDVI in QGIS

Derive an NDVI layer from your multispectral drone data for further analysis

Karen Joyce avatar
Written by Karen Joyce
Updated yesterday

What is the NDVI?

The Normalised Difference Vegetation Index (NDVI) is commonly used to simplify multispectral visualisation by combining the NIR and red reflectance into a single layer that can indicate vegetation health.

NDVI is calculated using the following equation:

(NIR - Red) / (NIR + Red)

When creating an NDVI layer, we apply this equation to every pixel in the multispectral image to return an output of between -1 and +1.

To learn more about how the NDVI is calculated and how to understand the output, check out this video.

Deriving NDVI

It's very simple to derive the NDVI (and other indices) on GeoNadir - learn more here.

However, if you would like to do this in QGIS, we cover the steps below. It might look complicated but I promise you it's not too bad and you can do it!

In brief, the video addresses:

  1. Upload your multispectral data to GeoNadir for processing

  2. When complete, download the multispectral orthomosaic

  3. Drag and drop the orthomosaic into QGIS

  4. Change the contrast and band display of the orthomosaic

  5. Use the raster calculator to apply the NDVI equation to your orthomosaic

  6. For best results, change the contrast of the resulting NDVI

  7. Use the identify features tool in QGIS to inspect individual NDVI pixel values

Did this answer your question?