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Raw corrected (L1A)

L1A sample image

Product description

The L1A Product is a raw, but corrected product from Satellogic’s products family. It is composed by the raw frames that have been radiometrically corrected along with the necessary metadata.

The algorithms applied to the L0 data to convert it into L1A are: - Artifacts removals - PSF Deconvolution - Radiometric correction to Top of the atosmphere units - HDR (combining 2 L0 frames with different exposures, only on Mark V) - Stray light correction - NO-data and cloud mask calculation

Given the nature of our payload design and operations, the L1A product is a set of overlaping frames, each with 4 areas corresponding to each of the RGBNir bands of the sensor.

Technical characteristics

Parameter

Mark IV

Mark V
Spectral bands

Blue : 450 - 510 nm
Green: 510 - 580 nm
Red : 590 - 690 nm
NIR : 750 - 900 nm

Blue : 450 - 517 nm
Green: 517 - 583 nm
Red : 597 - 690 nm
NIR : 759 - 890 nm

Frame size

5120 x 5120 pix

 9344 x 7000

GSD

0.7m - 1.35m 1

 0.70m - 0.81m 1

Swath

4.8 - 5.5 Km 1

 6.8Km - 8.5Km 1

Image bit depth

16 bit scaled TOA (0-10000)

⁠
Algorithms applied

Artifacts removal, PSF deconvolution, stray light correciton, radiometric correction, HDR

⁠
Geolocation Accuracy

<= 300m TBC CE90

⁠
Image format

GeoTiff, LZW loseless compression

⁠
Ancilliary files

Metadata (JSON), preview (PNG), thumbnail (PNG), cloud mask (TIF), cloud_statistics (CSV)

⁠

Product presentation

Each of the frames is 16-bit single band Grayscale GeoTIFF. The GeoTiff location is coarsly defined by the onboard satellite telemetry to help with the fine location process. Each of the frames contains 4 regions, corresponding to RGBNIR as depicted in the following image:

drawing

The size of each frame varies by platform beign 5120x5120 for Mark IV and 9344x7000 for Mark V.

The position of each band varies slightly between satellites and the exact position is defined in the metadata file for each frame.

Product components

Each L1A product, contains a preview, a thumbnail a metadata file, a cloud mask and a cloud_statistics file as well.

Raster, preview and thumbanil

drawing drawing drawing







Cloud mask and cloud statistics

drawing The mask is a single band GeoTiff. The values of the raster represent different cloud data as follows:

  • 0: nodata
  • 1: valid_data
  • 128: shadow_data
  • 255: cloud

The cloud statistics csv files contains a description of the detected cloud and saturated pixel count for each individual band. For example

scene_id band detected_cloud_coverage saturation
SL-newsat43-20240527T030147882889Z-micro-L1A-0.14.4 blue 0.0 7.059575547200715e-05
SL-newsat43-20240527T030147882889Z-micro-L1A-0.14.4 green 0.0 0.00032127568493150685
SL-newsat43-20240527T030147882889Z-micro-L1A-0.14.4 nir 0.0 2.7833692573525483e-07
SL-newsat43-20240527T030147882889Z-micro-L1A-0.14.4 red 0.0 0.00010316780821917808

Metadata file

The Metadata file is a JSON file that contains metadata about the satellite, the payload and the capture at the moment of taking that specific frame. The following parameters are expected on a JSON metada file of an L1A product.

Field name Description Example
supplier The name of the supplier of the imagery. Satellogic
productname The product name L0
scene_id The ID of the individual frame this metadata file corresponds to.
Format: SL-<satellite_id>-<timestamp>-<payload>-<product_name>-<version>		 SL-newsat43-20240527T030147897033Z-micro-L0-v0.1.8
sceneset_id The UUID of the entire capture this individual frame is part of. 81b495ff-1b2a-49a0-bb08-204ac31ae732
satellite_class The satellite class this individual frame is from. Valid options are [NewSat] NewSat
satellite_name The name of the satellite that took this frame.
Format: newsat-, with N>0		 newsat43
timestamp The timestamp of the corresponding individual frame, in ISO8601 2024-05-27T03:01:47.897033+00:00
footprint The estimated footprint of the individual frame. 
{
  "type": "Polygon",
  "coordinates": [
   [
    [
     151.2926010511119,
     -33.713019131320415
    ],
    [
     151.21924049959776,
     -33.695235769770775
    ],
    [
     151.23516759437442,
     -33.64939917428438
    ],
    [
     151.30852814588852,
     -33.6671920186592
    ],
    [
     151.2926010511119,
     -33.713019131320415
    ]
   ]
  ]
 }
metadata → sun_elevation Estimated sun elevation measured at the target at the moment of the capture. In degrees 33
metadata → exposure_us Exposure time in microseconds (us). Possible range: 0-1000000 4583
metadata → burnt_pixel_threshold DNs threshold to be used for computation of burnt_pixels 250
metadata → burnt_pixels Number of pixels over the burnt_pixels_threshold. Valid range: [0, width * height] 0
metadata → azimuth Azimuth expressed in Radians 0.2827841471
metadata → offnadir Offnadir expressed in Radians 0.06472428649
metadata → software_version_L0 Version of the product, using semver. v0.1.8
metadata → camera Specification of payload used for outcome_id. Possible options: [micro for MSI, macro for HSI] micro
metadata → satellite_model Satellite generation. For example MarkIV, MarkV, etc. MarkV
metadata → location_requested The initial location requested for the entire capture. If the associated capture refers to an Area (area coverage) then this is the centroid of the planned area. 
{
"altitude": 0.0,
"latitude": -33.8684,
"longitude": 151.2161
}
metadata → telemetry → estimated_error The estimated errors of the measurements provided in this document in deg, deg, deg, m, m 
{
"payload_attitude_roll_error":
  0.00303881073,
"payload_attitude_pitch_error":  
  0.0033185956,
"payload_attitude_yaw_error": 
 0.00298694815,
"satellite_position_error_xyz": 47,
"satellite_altitude_error": 47.2
}
metadata → telemetry → payload_attitude LVLH (“Local Vertical Local Horizontal” reference frame) to Payload.
The rotation between the Payload Reference Frame and Orbit Reference Frame in
 
{
"roll": 0.1662209217136321,
"pitch": 3.65127060124016,
"yaw": -96.99019650435964,
"qi": 0.02289759792844922,
"qj": -0.022197503617459674,
"qk": 0.7484874823859377,
"qr": -0.6623816570179316
}
metadata → telemetry → payload_attitude_ecef Estimated payload attitude with respect to ECEF 
{
"roll": 54.91229311994126,
"pitch": -11.115225411802388,
"yaw": 106.37762737879517,
"qi": 0.20616164868982098,
"qj": -0.41889617398559253,
"qk": 0.6803416618050814,
"qr": 0.564941229900976
}
metadata → telemetry → body2sensor_quaternion The satellite body to sensor quaternions 
{
"qr": -0.0028739884584221323,
"qi": -0.0029586435692281906,
"qj": -0.004557872346308913,
"qk": 0.999981106030632
},
metadata → telemetry → satellite_altitude The satellite altitude at the moment of the capture, in meters. 495173.0583
metadata → telemetry → satellite_nadir Estimated Nadir point in WGS84 at the moment of the capture 
{
"latitude": -33.73413011813329,
"longitude": 151.60113662203554
},
metadata → telemetry → satellite_posvel Position and velocity of the satellite 
{
"pos_x": -5032954.358480158,
"pos_y": 2721179.239210317,
"pos_z": -3796949.197049603,
"vel_x": 4409.801501309834,
"vel_y": -567.7075025111607,
"vel_z": -6271.424870965866
}
metadata → telemetry → satellite_attitude_calculated_ecef2body Estimated attitude of the satellite, with the refecence system ECEF. 
[
 -0.682659079864783, 
-0.4135383032464778,
 -0.20688691258855424,
 -0.5658272331955825
]
metadata → telemetry → location_calculated 
{ 
"latitude": -33.68122100977548, 
"longitude": 151.2639020596401, 
"altitude": -0.09642131812870502
}
metadata → product_metadata → satellite_serial_number Internal satelilte serial number. Format: FM FM45
metadata → product_metadata → time_range Start and end timestamps, in Unix time format, for the entire associated captures. 
[
1716778907.564665,
1716778913.118901
]
metadata → product_metadata → category Internal identification of the capture. Possilbe values: (production, engineering, no_process) production
metadata → product_metadata → bands Position and information of each of the bands present on the raw frame. Bands can be blue, green, red, nir 
"blue": {
"band_field_of_view": {
 "x_fov": 1.147225208113778,
 "y_fov": 0.18085003548283332
},
"band_indices": {
 "y_max": 1560,
 "y_min": 88
},
"center_of_band": {
 "cob_x_px": null,
 "cob_y_px": null
}
},
metadata → product_metadata → timestamp Timestamp of the individual frame in Unix time format 1716778907.564665

TOA Factors

The L1A product is calibrated into Top Of Atmosphere units. L1A frames are in units of reflectance which are a 0-100% value. In order to fit them in a standard Tiff file, the decimal percentage mapped to 0-10000 units. In order to convert it to radiance, calibration factors are included in the TOA_factors.json file in the radiance_to_reflectance field as can be seen in the follwoing example.

{
    "toa_product": "reflectance",
    "dn_to_toa": {
        "blue": 0.0005149058136425573,
        "green": 0.0005165027088655159,
        "nir": 0.0015526813957906338,
        "red": 0.0005702470410396718
    },
    "radiance_to_reflectance": {
        "blue": 3.066967270902978,
        "green": 3.243146439091673,
        "nir": 5.392975659309483,
        "red": 3.7239146733710684
    },
    "vicarious_factors": {
        "blue": {
            "bias_factor": 0,
            "scale_factor": 1.0217194978699562
        },
        "green": {
            "bias_factor": 0,
            "scale_factor": 0.9736846793952693
        },
        "nir": {
            "bias_factor": 0,
            "scale_factor": 1.1503664715826032
        },
        "red": {
            "bias_factor": 0,
            "scale_factor": 0.9820510061971801
        }
    }
}

Packaging specification

STAC API

The L1A product can be found in our STAC archives. Each frame of a capture is a single Item in the corresponding collection. The following metadata and assets are available for each

The following table shows the description of each field and an example corresponding to the capture used in previous section.

Field Description Example
datetime Capture date and time of the tile. In UTC 2024-05-27T03:01:47.897033+00:00
platform Satellite name that acquired the imagery newsat43
eo:cloud_cover The percentage of cloud cover (0-100) 0.0
view:off_nadir The off-nadir angle for the capture measured in degrees. 0.06472
view:sun_elevation The elevation angle of the sun at the target, at the moment of the capture, in degrees. 33
satl:outcome_id A unique identifier of the associated capture with this tile. 81b495ff-1b2a-49a0-bb08-204ac31ae732
satl:product_name The unique name of the product of which this tile corresponds to L1A
satl:product_version The version of the product. Uses semantic versioning. v0.14.4

Non documented parameters should be ignored.

Also, each item/tile contains the following assets/components:

STAC Item asset name Component
analytic The full resolution raster corresponding to the frame
preview A small preview of the raster
thumbnail A smallthubmnail of the raster.
metadata The JSON Metadata file describe above
cloud The raster cloud mask
toa_factors A GeoJson file containing the TOA calibration factors
cloud_statistics The cloud statistics report file as CSV

Packaged scene

If delivered as a package scene (via S3, FTP, or Zip download link) an L1A capture is packaged in the following format:

Scenes are delivered as a single folder. The file name follow the following format: SL-<SATELLITE_NAME>-<DATE>-<PAYLOAD>-L1A, for example like SL-newsat43-20240527T030147897033Z-micro-L1A.

Inside each package, a flat structure can be found with all corrsponding frames and their associated ancilliary files.

The following files and folders can be found in a typical scene: 

.
├── SL-<SATELLITE_NAME>-<DATE>-<PAYLOAD>-L1A-<VERSION>_anaytic.tiff
├── SL-<SATELLITE_NAME>-<DATE>-<PAYLOAD>-L1A-<VERSION>_preview.png
├── SL-<SATELLITE_NAME>-<DATE>-<PAYLOAD>-L1A-<VERSION>_thumbnail.png
├── SL-<SATELLITE_NAME>-<DATE>-<PAYLOAD>-L1A-<VERSION>_metadata.json
├── SL-<SATELLITE_NAME>-<DATE>-<PAYLOAD>-L1A-<VERSION>.json

File Description
*_analytic.tiff The full resolution raster for the individual frame
*_preview.png The preview component of the product for the entire scene
*_thumbnail.png A low resolution thumbnail of the scene
*_metadata.json The metadata JSON attachment
*_cloud_mask.tif The raster cloud mask
*_cloud_statistics.csv The cloud statistics report file as CSV
*.json A STAC metadata dump of the item in the archive.
*_toa_factors.json A GeoJson file containing the TOA calibration factors

Known issues for current version v0.14.4

-

Changelog

[v0.14.4] 03-07-2024

  • Initial release

  1. Varies with altitude of the satellites and off nadir angle. ↩↩↩↩

Last update: 2024-07-03