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HOTSPOT service specifications


This service performs a hotspot detection algorithm. It takes as input a single calibrated optical dataset containing nir and swir22 spectral bands to generate a hotspot bitmask, representing areas of active fire.

📕 The tutorial of the HOTSPOT service is available in this section.

Service Description

The Hotspot Detection (HOTSPOT) service employs an hotspot algorithm that requires in input a Calibrated Dataset having at least nir and swir22 assets (e.g. for Sentinel-2 MSI those are respectively the 8A and 12 bands). It calculates the ratio and the difference between those assets in TOA reflectance:

\[ ratio = { swir22 \over nir } \]
\[ delta = swir22 - nir \]

Pixels over water are masked and then excluded from the hotspot detection in case of TOA reflectance for swir22 asset is minor than 0.04. Hotspot and candidate hotspots are then identified using the following expressions:

\[ hotspot = { ratio>2 } , { delta>0.15 } \]
\[ candidate_{hotspot} = { ratio>1.1 } , { delta>0.1 } \]

The algorithm performs a background characterization around candidate hotspot pixels in case of a large fire event. The aggregated hotspot size is increased if the number of candidate fire pixels is less than the half of the total pixels in the window (approximately 2x2 km). Statistics (mean and standard deviation of the ratio) are also computed for pixels within the windows considered in the background characterization. In a later stage, the algorithm undertakes contextual tests which are needed to decide for all candidate hotspot pixels if they can be classified as hotspot or not.

In this process, two conditions needs to be satisfied to classify a candidate pixel as hotspot:

  1. ratio > ratio_mean + max((3 * ratio_std), 0.5),

  2. swir22 > swir22_mean + max((3 * swir22_std), 0.05).

Finally, the algorithm returns the hotspot classification of the entire scene as a binary mask (No-Fire=0, Hotspot=1). Output binary classification of active fires is given as single band raster in COG format.


The integrated algorithm does not perform any cloud/smoke masking of source EO data.


This processor uses as input a calibrated product from the Optical Products having swir22 and nir STAC assets. HOTSPOT supports Calibrated Datasets from the following EO missions:

  • Sentinel-2,

  • Landsat-8, Landsat-9.


The HOTSPOT service requires a specified number of mandatory and optional parameters. All service parameters are listed in the table below.

Parameter Description Required Default value
Optical calibrated dataset Optical calibrated dataset with red, nir and swir22 assets YES
Area of Interest Area of interest expressed in WKT NO

Table 1 - Service parameters of the HOTSPOT processor.

Optical calibrated dataset

The first parameter represents the reference to the input optical calibrated dataset that is used to detect hotspots.


The input product reference refers to a calibrated optical multi-spectral dataset having at nir, and swir22 assets. Therefore, an Optical Calibrated Dataset having only nir asset cannot be used as input for HOTSPOT.


The drag and drop of the single-band asset (e.g. "nir") is not possible. Users must drag and drop only a Calibrated Dataset (e.g. "[CD] SENTINEL-2A MSI L2A 96 2023-02-07 14:37:31") into both Flood event image and Reference event image fields.

AOI (optional)

This second parameter (optional) may define the area of interest expressed as a Well-Known Text value.


The HOTSPOT processor generates the following products:

  1. Hotspot binary mask (1=true=fire, 0=false=not-fire),

  2. Hotspot overview (true values in red with transparency set for false values).

HOTSPOT Product Specifications can be found in the below tables:

Long Name Hotspot overview
Short Name overview-hotspot
Description Hotspot bitmask in red color scale
Processing level L1C / L2
Data Type Unsigned 8-bit Integer (UInt 8)
Band 4
Format COG
Projection EPSG:4326 - WGS84
Units N/A
Valid Range [1 - 255]
Fill Value 0

Long Name Hotspot bit mask
Short Name hotspot
Description Bitmask from hotspot detection based on nir08 and swir16 reflectances
Processing level L1C / L2
Data Type 1-bit
Band Single
Format COG
Projection EPSG:4326 - WGS84
Units N/A
Valid Range [0 - 1]
Fill Value N/A

Vectorize HOTSPOT single band asset

HOTSPOT's binary mask can be converted to polygons by using the FilterVectorize service in Vectorize mode and selecting only true values DN=1 (hotspot).


Only the hotspot single band asset can be used in the FilterVectorize on-demand service, being the only discrete raster produced by the HOTSPOT service.