NDVI Analysis and Reclassification in ArcGIS Pro: Landsat & Sentinel Workflows

Introduction

Normalized Difference Vegetation Index (NDVI) is used to quantify vegetation greenness and is useful in understanding vegetation density and assessing changes in plant health. It is a numerical indicator which uses the visible and near-infrared bands of the electromagnetic spectrum.

Purpose Of NDVI Analysis

1)  To estimate agricultural parameters such as crop yields, pasture performance, and rangeland carrying capacity.

2)  To enhance vegetation analysis using remotely sensed data for large and diverse landscapes.

3)  To differentiate major land cover categories such as savannah, dense forest, non-forest areas, and agricultural fields.

4)  To distinguish between evergreen and seasonal forest types based on vegetation greenness and reflectance patterns.

To estimate key vegetation properties such as Leaf Area Index (LAI), biomass, chlorophyll concentration in leaves, plant productivity, fractional vegetation cover, and levels of plant stress.

NDVI Calculation

Formula: (NIR – Red) / (NIR + Red)

In Landsat Series (Landsat 8 / 9 – OLI Sensor), NDVI = (Band 5 – Band 4) / (Band 5 + Band 4).

In Sentinel-2 Bands, NDVI = (B8 – B4) / (B8 + B4)

Vegetated areas strongly reflect the NIR part of the spectrum and absorb the red light of the visible portion of the spectrum.

NDVI values range from -1 to 1. In general, the NDVI values are negative for waterbodies, close to zero for rocks, sands or concrete surfaces, and positive for vegetation, including crops, shrubs, grasses and forests.

Methodology

Step 1: Add Landsat Bands

Open ArcGIS Pro → Map → Add bands (band 4 and 5 respectively).

Step 2: Open Raster Calculator

Go to Analysis → Tools → Search “ Raster Calculator”.

Step 3: Enter NDVI Expression

In Raster Calculator enter the NDVI Expression, float (“Band 5” – “Band 4 “)/float(“Band 5”+ Band 4“), then give output raster name.

Step 4: Run the tool

Click Run

NDVI raster will be generated.

Step 5: Change Symbology

Right-click the NDVI layer → Symbology

Apply a suitable color ramp (e.g., green for vegetation, yellow/red for bare land, waterbodies etc).

Reclassify NDVI Values

The reclassify tool reclassifies (or changes) the values in a raster.

Step 1: Open Reclassify tool

Go to Analysis→ tools → spatial analyst tool → reclass → reclassify.

Step 2: Set Reclassification parameters

Choose Input Raster (your NDVI output)

Select Reclass Field

Choose the method: Manual breaks or Equal Interval

Assign new class ranges

Step 8: Run the Tool

Click Run

Reclassified NDVI raster will be created.

Conclusion

The NDVI analysis successfully extracted vegetation information from Landsat imagery by utilizing the Red and NIR bands. The generated NDVI raster clearly differentiated vegetation from non-vegetated areas based on reflectance characteristics. Reclassification of the NDVI values further simplified interpretation by grouping the continuous NDVI range into meaningful vegetation classes. This process enhances the understanding of vegetation distribution and supports better visualization, mapping, and analysis for various environmental and land-management applications. Overall, NDVI calculation and reclassification in ArcGIS Pro proved to be an effective method for identifying and representing vegetation patterns within the study area.