Raw corrected (L1A)
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 |
Blue : 450 - 517 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:
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
Cloud mask and cloud statistics
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- |
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. |
|
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. |
|
metadata → telemetry → estimated_error | The estimated errors of the measurements provided in this document in deg, deg, deg, m, m |
|
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 |
|
metadata → telemetry → payload_attitude_ecef | Estimated payload attitude with respect to ECEF |
|
metadata → telemetry → body2sensor_quaternion | The satellite body to sensor quaternions |
|
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 |
|
metadata → telemetry → satellite_posvel | Position and velocity of the satellite |
|
metadata → telemetry → satellite_attitude_calculated_ecef2body | Estimated attitude of the satellite, with the refecence system ECEF. |
|
metadata → telemetry → location_calculated |
|
|
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. |
|
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 |
|
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