SkySat

Long name SkySat
Short name SST
Sensor type Optical: CMOS frame camera with panchromatic (0.86 meter) and multispectral (1 meter) halves
Platform SkySat
Key file name (use to open dataset) *_metadata.json
Supported file name extensions .json, .tif, .txt
Sections

Data product name and description
Distribution disk files
Returned data for supported format
References

Data product name and description

SkySat is a constellation of sub-meter resolution Earth observation satellites owned by Planet Labs.

SkySat imagery is captured in a continuous strip of single-frame images known as scenes which are all are acquired in the blue, green, red, near infrared (NIR), and panchromatic bands. The SkySat products was designed for a wide variety of applications that require imagery with an accurate geolocation and cartographic projection.

The following SkySat data products are supported by GDB:

SkySat Basic Scene products

The SkySat Basic Scene product includes Analytic, Analytic DN, L1A Panchromatic DN, and Panchromatic imagery that is uncalibrated and in a raw digital number format. The Basic Scene Product is not corrected for any geometric distortions inherent in the imaging process.

SkySat Ortho Scene products

The SkySat Ortho Scene product includes Visual, Analytic DN, Analytic, Panchromatic, and Pansharpened Multispectral imagery. The Ortho Scene product is sensor-and geometrically-corrected and is projected to a cartographic map projection. The geometric correction uses fine Digital Elevation Models (DEMs) with a post spacing of between 30 and 90 meters.

SkySat Collect products

The SkySat Collect product is an orthorectified composite of SkySat scenes. The number of scenes included ranges from approximately 50-70 SkySat scenes and contains 4 multispectral bands, as well as the panchromatic band. It is sensor and geometrically corrected and is projected to a cartographic map projection.

Note: The information provided herein is based on the data distributor's documentation cited under References.

Spectral bands:
Spectral range (nm)

Spatial resolution (m)*
(spectral resolution)

Maximum image dimensions
(Across track x along track, km)

Notes

B1 (Blue):  450 - 515
B2 (Green): 515 - 595
B3 (Red): 605 - 695
B4 (NIR): 740 - 900
PAN(Panchromatic): 450 - 900

[SkySat-1, SkySat-2]
PAN: 0.86 (Panchromatic)

[SkySat-3 - SkySat-7]
PAN: 0.72 (Panchromatic)

MS:  1.0 (Analytic)

SkySat Scene:
3.199 x 1.349

SkySatCollect:
15km x 8km

  • SkySat satellites have three cameras per satellite, which capture overlapping strips. Each strip contains overlapping scenes.
  • 16-bit, unsigned integer, MS and PAN imagery (12-bit data depth).
  • Cross-sensor, non-uniformity correction (1 percent), color balancing across cameras.
  • Idealized sensor model and Rational Polynomial Coefficients (RPC) bands are coregistered.

* Resolution is always nadir position unless noted otherwise.

The available product types for SkySat Basic scenes are as follows:

Product type Description Notes

Analytic
Analytic DN

4-band Analytic(DN) image (Blue, Green, Red, NIR)

- Non-orthorectified, radiometrically corrected, multispectral BGRN
- Non-orthorectified, multispectral BGRN

Panchromatic
Panchromatic DN
L1A Panchromatic DN

1-band Panchromatic (DN) image

- Non-orthorectified, radiometrically corrected, panchromatic (PAN)
- Non-orthorectified, panchromatic (PAN)
- Non-orthorectified, pre-super resolution, panchromatic (PAN) (not tested)

The available product types for SkySat Ortho scenes are as follows:

Product type Description Notes
Visual 3-band Image (Red, Green, Blue) - Orthorectified, pansharpened, and color-corrected (using a color curve) 3-band RGB Imagery (not tested)
Pansharpened Multispectral 4-band Image (Red, Green, Blue, NIR) - Orthorectified, pansharpened 4-band BGRN Imagery

Analytic SR
Analytic
Analytic DN

4-band Analytic (DN) Image (Blue, Green, Red, NIR)

- Orthorectified, multispectral BGRN. Atmospherically corrected Surface Reflectance product
- Orthorectified, multispectral BGRN. Radiometric corrections applied to correct for any sensor artifacts and transformation to top-of-atmosphere radiance
- Orthorectified, multispectral BGRN, uncalibrated digital number imagery product

Panchromatic
Panchromatic DN

1-band Panchromatic (DN) image

- Orthorectified, radiometrically correct, panchromatic (PAN)
- Orthorectified, panchromatic (PAN), uncalibrated digital number imagery product

Distribution disk files

Warning: Data sets for this sensor are organized in a specific folder structure on disk. GDB uses this structure and the file names to identify the data product type. Do not alter the folder structure or any file names prior to data ingestion to ensure the image data and auxiliary information are imported correctly.
You can open a SkySat data set by selecting the *_metadata.json file.
Note: When entering the file name of the dataset in EASI/PACE, enter *_metadata.json-productType.

When opening a SkySat dataset, the files read by GDB are described in the following table.

File name Format Required Contents/details
*_metadata.json GeoJSON Yes Key file name, contains data set metadata


*_analytic_dn.tif
*_analytic_clip.tif
*_analytic_SR_clip.tif

*_panchromatic_dn.tif
*_ortho_panchromatic_clip.tif

*_pansharpened.tif

GeoTIFF Yes Image data


*_analytic_dn_RPC.txt

*_panchromatic_RPC.txt

RPC data Yes

Text file of Rational Polynomial Coefficients
(Only availiable for basic products)


*_analytic_udm.tif
*_panchromatic_udm.tif
*_pansharpened_udm.tif

GeoTIFF Optional

Unusable Data Mask (UDM)
Not tested (not included in current test data)

Returned data for supported format

SkySat data can be opened directly in its raw vendor format or imported into a PCIDSK (*.pix) file using the key file name (*_metadata.json). For optimal processing, use the PCIDSK format.

The following table describes the data structure after it is opened by GDB.

Data product Data returned Details/notes



Analytic



4 x [16U] raster channels
1 x [BIN] rational function model



4-band Analytic Image (Blue, Green, Red, NIR)

RFM only available for basic product



Panchromatic



1 x [16U] raster channel
1 x [BIN] rational function model



1-band Panchromatic Image

RFM only available for basic product



Pansharpened



4x [16U] raster channels



4-band Image (Blue, Green, Red, NIR)

References

Planet Imagery Product Specifications. SkySat Imagery Products. Planet Labs Inc. January 2018. 57 pages.

For more information, visit: planet.com

Download a PDF copy of the specifications: Planet Imagery Products

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