> For the complete documentation index, see [llms.txt](https://satdocs.hydrosat.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://satdocs.hydrosat.com/product-details/changelog.md).

# Changelog

A list of satellite data product updates, including release dates and key features.

{% updates format="full" %}
{% update date="2026-09-08" tags="quality-control" %}

## Image Quality Logs

Quality logs are now available in STAC item metadata (`hydrosat:quality_log`).

These logs offer more context about acquisition and processing conditions so that users can better understand quality characteristics across scenes.

| Quality Log                          | What It Means                                                                                    |
| ------------------------------------ | ------------------------------------------------------------------------------------------------ |
| `Insufficient illumination for VNIR` | The sun's elevation was low during acquisition. This may reduce the quality of the VNIR imagery. |
| `Geolocation out of spec`            | Geolocation for the scene does not meet the expected accuracy.                                   |
| `Georeference failure`               | The nominal georeference procedure did not complete as expected.                                 |
| `Extreme cold values clipped`        | Some pixels contain fill values. Use the `QUALITY_ASSURANCE` mask for details.                   |
| {% endupdate %}                      |                                                                                                  |

{% update date="2026-08-25" tags="cloud-mask" %}

## Cloud Mask Improvements

We've deployed a new version of our cloud detection model using a significantly larger and more diverse training dataset. This results in fewer false positives in the cloud mask and improved detection performance across a wider range of cloud conditions.
{% endupdate %}

{% update date="2026-05-21" tags="processing" %}

## Footprint Geometry Correction

We've deployed a minor fix to ensure representativeness of STAC item footprint geometries with actual imaged area.
{% endupdate %}

{% update date="2026-03-31" tags="processing" %}

## Coregistration Improvements

We've refined our mutual information-based coregistration workflow for improved feature matching between the LWIR and VNIR data.
{% endupdate %}

{% update date="2026-02-24" tags="processing" %}

## Geometric Processing Improvements

We've updated our georeferencing and VNIR band alignment workflows to improve geolocation accuracy and band-to-band registration. This release includes:

1. An enhanced optical distortion correction to reduce residual along-track offsets
2. Use of a digital elevation model (DEM) to improve band-to-band registration over complex terrain
   {% endupdate %}

{% update date="2026-02-05" tags="product-update" %}

## Level-1 Unit Changes

We've modified the units for our Level-1A and Level-1B data products.

#### Before The Change

Previously, L1A and L1B imagery assets contained per-band digital number data. To arrive at radiance, the user needed to apply gain and offset coefficients provided in product metadata.

#### After The Change

**Level-1A Products**

* L1A imagery assets now natively contain per-band top-of-atmosphere (TOA) radiance values. Gain and offset coefficients are applied as part of Hydrosat's data processing.
  * Units: W/m<sup>2</sup>/sr/μm
  * Scaling factor: 0.01 (VNIR), 0.0001 (LWIR)

**Level-1B Products**

* L1B imagery assets contain per-band TOA reflectance data (for VNIR bands) and brightness temperature data (for LWIR bands).
  * Units: Unitless (VNIR); Kelvin (LWIR)
  * Scaling factor: 0.0001 (VNIR); 0.01 (LWIR)

**Conversions**

* Hydrosat provides a full suite of coefficients in product metadata for conversion between TOA radiance and reflectance (or brightness temperature). For more information on usage, see [this page](https://satdocs.hydrosat.com/product-details#conversions) or our product guide.
  {% endupdate %}

{% update date="2026-01-27" tags="thumbnails" %}

## Thumbnail Colorization Improvements (LWIR)

We've improved the contrast and visual consistency in our L1B and L2 thermal thumbnails and previews. This includes:

* Consistent scaling across the full imaging strip rather than within individual scenes.
* A switch from the `inferno` color ramp to a modified `RdYlBu_r` color ramp, where cooler pixels are shown in blue and warmer ones in red. These colors map to predictable temperatures; the breakpoint from blue to yellow occurs at approximately 0 degrees Celsius.

This change has no impacts on the underlying data.
{% endupdate %}

{% update date="2026-01-20" tags="processing" %}

## Noise Mitigation

We've implemented a minor correction for noise in the thermal products.
{% endupdate %}

{% update date="2026-01-14" tags="thumbnails" %}

## Thumbnail Colorization Improvements (RGB)

We've released a color curve approach that improves the visual contrast in our true color thumbnails. This change has no impacts on the underlying data.
{% endupdate %}

{% update date="2025-12-17" tags="cloud-mask" %}

## Updated Cloud Mask

We've released an improved cloud mask, which uses a U-Net convolutional neural network architecture. The new model outperforms our baseline Fmask approach across several key metrics.
{% endupdate %}
{% endupdates %}