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# The Enhanced Vegetation Index (EVI) comes to Atlas
- URL: https://le.mu/blog/the-enhanced-vegetation-index-evi-comes-to-atlas/
- Published: 2026-11-09T13:00:00.000Z
- Updated: 2026-11-10T00:25:20.000Z
- Description: How much of a place has dense, vigorous vegetation, active vegetation or bare ground, and how that changes month by month since 2020. Atlas calculates it from Sentinel-2 imagery at 10 m.
- Author: Facundo Luis Menéndez
- Tags: Atlas, Indicators, #blog-col

## What the indicator is

Atlas’s new EVI indicator shows, month by month, how much of a zone has active vegetation, dense and vigorous vegetation, or no vegetation. It is calculated from Sentinel-2 imagery and covers January 2020 to September 2026.

EVI (*Enhanced Vegetation Index*) measures the vigor and density of vegetation. Compared with NDVI, it corrects for the atmosphere and the soil, and it saturates later over dense cover such as forests. Huete et al. (2002) developed it for NASA’s MODIS sensor.

## Highlights

- **Sentinel-2 data:** optical imagery from the European Space Agency’s Copernicus mission, free to use, with a revisit every five days.
- **One image per month:** each month is summarized in a geometric median composite, which reduces the effect of clouds, shadows and outliers.
- **Three simple classes:** EVI values are grouped into no vegetation or degraded, active vegetation, and dense and vigorous vegetation, using fixed ranges.
- **Monthly series since 2020:** data from January 2020 to September 2026, to show trends and seasonality.

## Technical specifications

| Attribute                   | Value                                                            |
| --------------------------- | ---------------------------------------------------------------- |
| Source                      | Sentinel-2 (ESA, Copernicus program)                             |
| Geographic coverage         | Global: any zone in the world                                    |
| Bands used                  | Blue (B2), red (B4) and near infrared (B8)                       |
| Cloud mask                  | Cloud Score+ (Google)                                            |
| Spatial resolution in Atlas | 10 m                                                             |
| Frequency                   | Monthly                                                          |
| Composite                   | Monthly geometric median                                         |
| Series available            | January 2020 to September 2026                                   |
| Classes                     | 3, by EVI range, plus “No data” for pixels under cloud or shadow |
| Units in Atlas              | Hectares and % of the valid area (excluding “No data”)           |
| Downloads                   | CSV, SVG, PNG                                                    |

## EVI classes

Each pixel of the monthly composite is assigned to one of three classes according to its EVI value.

| Class                         | EVI range        | What it usually represents                        |
| ----------------------------- | ---------------- | ------------------------------------------------- |
| No vegetation / degraded      | Below 0.2        | Bare soil, degraded areas and artificial surfaces |
| Active vegetation             | 0.2 to below 0.5 | Shrubs, grasslands, crops and open forests        |
| Dense and vigorous vegetation | 0.5 or above     | Dense forests and mature crops                    |

## Nonguén National Park in Atlas

In September 2026, 93.11% of the valid area of Nonguén National Park (3,029.46 ha, Biobío Region, Chile) shows as active vegetation.

![EVI screen in Atlas (Spanish interface) for Nonguén National Park, September 2026: a donut chart with the area per class, the class table with its ranges and a 3D view of the forest with a dense-vegetation pixel selected.](https://le.mu/content/images/2026/11/evi-atlas-nonguen-2026-09.jpeg)

The EVI indicator in Atlas for Nonguén National Park, September 2026 (Spanish interface)

| Class                         | % of the valid area |
| ----------------------------- | ------------------- |
| Active vegetation             | 93.11%              |
| Dense and vigorous vegetation | 3.83%               |
| No vegetation / degraded      | 3.05%               |

Nonguén is mostly native forest, and still only 3.83% shows as dense and vigorous vegetation. This is EVI’s seasonal effect: September is the end of the southern winter, when photosynthetic activity is lower. In summer the share rises: in January 2024, Atlas records 1,657 ha of dense vegetation in the park, more than half its area.

In Atlas, the panel shows the area of each class in a donut chart, next to the table of ranges and the description of each class. The map colors each pixel by its class, and each class can be hidden or centered from the table. The period selector steps through the series month by month.

## Methodology

1. All Sentinel-2 images of the month over the zone are gathered. Days with more than 20% cloud are discarded, and on the remaining days so are the pixels that Cloud Score+ flags as cloud or shadow.
2. A monthly geometric median composite is calculated: for each pixel, the multiband median of all valid observations in the month. It keeps the relationship between bands and filters out residual clouds and shadows.
3. EVI is calculated on the composite from the blue (B2), red (B4) and near-infrared (B8) bands, with the standard coefficients of Huete et al. (2002):

`EVI = 2.5 × (NIR − Red) / (NIR + 6 × Red − 7.5 × Blue + 1)`

1. Each 10 m pixel is assigned to a class using the ranges in the class table. Masked pixels become “No data”.
2. Atlas adds up the area of each class within the selected zone and shows it in hectares and as a percentage of the valid area.

## Use cases

- **Monitoring protected areas and conservation land:** follow month by month whether vegetation holds, recovers or degrades.
- **Post-fire and restoration tracking:** compare the same month across years to see how recovery is progressing.
- **Agriculture and grassland management:** identify the growth cycle and detect areas with low vigor.
- **Sustainability and nature reporting:** back the state of a site’s vegetation cover with satellite data.

## Limitations and how to read it well

- **Compare the same month across years:** EVI varies with the season, so a low value in winter does not mean degradation.
- **Classes measure vigor:** a native forest can show as active vegetation in months of lower activity. To know what cover is there, combine it with Land Use (CONAF).
- **Persistent cloud:** pixels under cloud or shadow become “No data” and do not count toward the percentage. A month in which no day passes the cloud filter is left empty in the series.
- **Snow and ice:** EVI rises over snow or ice. In high mountains or at high latitudes, a high winter value may come from snow.
- **Fixed thresholds:** the ranges are the same everywhere and are not adjusted by ecosystem.