This project, like many of my others, began far from a computer screen — in the middle of the Strabrechtse Heide, a heathland in the Netherlands. During a family walk, my mother, who visits the area often, remarked how the heather seemed to be fading. Once vibrant and purple, the plants were now being overtaken by grasses that flourish in nitrogen-rich soil.
That observation stuck with me. Back home, I began to wonder: could I trace this change using remote sensing data? This page walks you through how I tried to answer that question.
Area of Interest
To get a first impression of the area, I started with a true color satellite image of the Strabrechtse Heide. This is what the landscape looks like from above — a familiar view for remote sensing, and a helpful baseline before diving into more analytical layers.
Soil Adjusted Vegetation Index (SAVI)
To highlight vegetation, I used the Soil Adjusted Vegetation Index (SAVI). Similar to the better-known NDVI, SAVI measures how “green” an area is — but it also corrects for the influence of bare soil, which is helpful in semi-open landscapes like heathlands.
In this visualization, higher SAVI values (darker green) suggest denser vegetation cover, including both heather and grasses.
Green mask – Treshold classification
Next, I applied a threshold to the SAVI values. Pixels with a SAVI above this threshold were classified as “green” — meaning they likely represent healthy vegetation.
This mask gives a simplified view: not of what type of vegetation is present, but where it’s thriving.
Visualizing change
To see how the landscape evolved over time, I compared the green masks of two years: 2018 and 2020.
The resulting visualization shows where vegetation has increased (yellow) and where it has declined (blue). It’s a direct way to spot local changes — subtle on the ground, but visible from above.
Comparing yearly overview
Finally, I looked at the total number of green-classified pixels per image. This simple graph shows how “green” the area was over time — not just where things changed, but how much. It’s a rough but useful indicator of overall vegetation trends in the Strabrechtse Heide.
Looking at the results, my mum’s feeling seems spot on. An increase in green. There can be different explanations for the cause. But it’s interesting to see it validated in the data.