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Archive preview (L1B thumb)

Quickview thumbnail sample image

Product description

The Archive Preview product is a single, low resolution (20m pixel size) 4-band GeoTIFF mosaic built from all the L1 Basic (L1B) VISUAL tiles that compose a capture. Instead of exposing a capture as a collection of many small tiles, this product condenses the entire capture into one single raster, so that the whole outcome can be located, rendered and explored at a glance.

Because it covers a full capture in a single asset, it is published as one STAC item per capture, linked to its source capture through the satl:outcome_id property.

API only product

This product is not packaged for delivery to clients and cannot be ordered or downloaded as a standalone product. It is only accessible through the Archive STAC API, and exists to power catalog browsing experiences: it is the base collection used to populate and preview the archive, and is the imagery layer that Aleph uses to render captures when exploring the archive.

Technical characteristics

Parameter Value
Spectral bands

Red, Green, Blue, NIR
GSD

20 m
Coverage

Full capture footprint, one item per capture (satl:outcome_id)
Image bit depth

8-bit
Algorithms applied

Mosaicking and downsampling of L1B VISUAL tiles, reprojection to Web Mercator
Image format

GeoTiff, LZW lossless compression
Ancillary files

Cloud mask (GeoTiff), preview (PNG) and thumbnail (PNG).

Projection

Unlike other processing levels, which are projected to UTM, this product is projected to Web Mercator (EPSG:3857) so that it can be readily consumed by web mapping clients, such as the one used in Aleph. The projection is indicated in the proj:epsg property of the item.

STAC item

Collection: quickview-visual-thumb

Assets

  1. analytic
  2. cloud
  3. preview
  4. thumbnail

Note

Non documented files or parameters should be ignored.

All assets follow the same basename template.

{DATE}_{TIME}_SN{SATELLITE}_{PRODUCT_NAME}_{GSD}_{VERSION}_{SUFFIX}.{EXTENSION}

  • DATE: Year(4 digits)month(2 digits)day(2 digits)
  • TIME: Hour(2 digits)minute(2 digits)second(2 digits)
  • SATELLITE: Satellite number
  • PRODUCT_NAME: QUICKVIEW_VISUAL_THUMBNAIL
  • GSD: Ground sample distance of the mosaic, always 20m
  • VERSION: The product version, with dots replaced by underscores, inherited from L1B
  • SUFFIX: Depends on the asset
  • EXTENSION: Depends on the asset type

All time values refer to the capture time in UTC. Hence the string 20261016_073809 represents actually 2026-10-16 07:38:09.

Raster

The analytic asset is an 8-bit, 4-band (Red, Green, Blue, NIR) GeoTIFF at 20m GSD, covering the full extent of the capture in a single file.

Cloud

The cloud mask is provided as a single band GeoTIFF. It is built by joining all the L1B tiles' cloud masks and resampling them to the same grid as the analytic asset.

Check here for details on how they are computed.

Preview and thumbnail

Downsampled versions of the analytic asset are included in .png format, as in every other processing level.

Metadata

Metadata is available per item, in STAC format. The following table shows the description of each field and an example corresponding to the sample item used throughout this page.

Prefix Field Name Description Example
n/a id Unique identifier for the STAC item. 
20261016_073809_SN47_QUICKVIEW_VISUAL_THUMBNAIL_20m_1_11_0_e7717778-8b3d-4e64-915a-a4e90b5da188
n/a bbox Item bounding box. 
[
  48.3663381549022,
  30.6342862633218,
  48.5581876632321,
  30.8000402054266
]
n/a geometry Footprint of the valid image data for the capture. 
{
  "type": "Polygon",
  "coordinates": [[...]]
}
n/a tile_geometry Footprint of the full mosaic extent, including areas with no valid data (nodata). 
{
  "type": "Polygon",
  "coordinates": [[...]]
}
n/a collection Collection name. 
quickview-visual-thumb
n/a assets List of the assets available for the item. 
{
  "cloud": {...},
  "preview": {...},
  "analytic": {...},
  "thumbnail": {...}
}
assets.analytic eo:bands The bands contained in the analytic raster. 
[
  {"name": "Red", "common_name": "red"},
  {"name": "Green", "common_name": "green"},
  {"name": "Blue", "common_name": "blue"},
  {"name": "NIR", "common_name": "nir"}
]
properties gsd The ground sampling distance of the image, in meters. Always 20 for this product. 
20
properties datetime Capture date and time. In UTC. 
2026-10-16T07:38:09.063549+00:00
properties platform Satellite name that acquired the imagery. 
newsat47
properties proj:epsg The EPSG code of the projection. Always Web Mercator for this product. 
3857
properties proj:shape Dimensions of the mosaic in pixels (Height x Width). Varies with the extent of the capture. 
[900, 900]
properties proj:transform Affine transform mapping pixel coordinates to the projected CRS. 
[20, 0, 247999.44, 0, -20, 3410000.38, 0, 0, 1]
properties eo:cloud_cover The percentage of cloud cover found on the image, from 0 to 100. In rare instances where cloud cover cannot be calculated, a sentinel value of 999 is assigned.a 
0
properties view:off_nadir The off-nadir angle for the capture measured in degrees. 
38.2539
properties view:sun_azimuth The azimuth angle of the sun at the target with respect to the north, in degrees. 
154.5554
properties view:sun_elevation The elevation angle of the sun at the target at the moment of the capture, in degrees. 
48
properties satl:outcome_id A unique identifier of the capture this item is built from. 
e7717778-8b3d-4e64-915a-a4e90b5da188
properties satl:ground_lock Indicates if there was enough GCP on the ground to geolocate the image. A false value indicates that the location of the image was done with onboard telemetry from the satellite and not a basemap. 
true
properties satl:valid_pixel The percentage of valid pixels on the tile. If less than 100 it means that part of the image contains no data values.a 
89.6998
properties satl:haze_cover The percentage of haze on the image, from 0 to 100 [experimental use]. In rare instances where cloud cover cannot be calculated, a sentinel value of 999 is assigned.a 
0.1329
properties satl:product_name The unique name of the product. 
QUICKVIEW_VISUAL_THUMBNAIL
properties satl:product_version The version of the product. Uses semantic versioning. Inherited from the product version of the corresponding L1B tiles. 
1.11.0
properties satl:satellite_generation Satellite model category. 
MarkV
properties satl:transaction_id Internal processing transaction identifier. 
rr-to-stac-nkrvs
properties satl:ba_[BAND]_response The FFT phase correlation response between the [BAND] and the Green band. [BAND] can be Red, Blue, NIR. Typically a number >0.5 means there is good correlation between [BAND] and the Green band.a 
1.1415
properties satl:ba_[BAND]_radial Radial error between the [BAND] band and the Green band, in pixels.a 
0.1272
properties satl:ba_[BAND]_xshift X direction error between the [BAND] band and the Green band, in pixels. [BAND] can be Red, Blue, NIR.a 
0.0176
properties satl:ba_[BAND]_yshift Y direction error between the [BAND] band and the Green band, in pixels. [BAND] can be Red, Blue, NIR.a 
0.0252
properties satl:geoaccuracy_[BAND]_radial Radial error for the [BAND] band with respect to the basemap, in meters. [BAND] can be Red, Green, Blue, NIR.a 
2.2374
properties satl:geoaccuracy_[BAND]_xshift X direction error between the [BAND] band with respect to the basemap, in meters. [BAND] can be Red, Green, Blue, NIR.a 
-1.0252
properties satl:geoaccuracy_[BAND]_yshift Y direction error between the [BAND] band with respect to the basemap, in meters. [BAND] can be Red, Green, Blue, NIR.a 
-1.5654
properties satl:geoaccuracy_[BAND]_response The FFT phase correlation response between the Green band and the [BAND]. [BAND] can be Red, Green, Blue, NIR. Typically a number >0.5 means there is good correlation between the basemap and the image being measured. For tiles with a value lower than that, the remaining geoaccuracy measurements are not relevant.a 
0.7518

\(^a\) This metric is an aggregation of this field across the set of L1B tiles that compose the capture.