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

For more information on SkySatCollect product, visit: