Data Format and Structure

Data Format

Images are stored in the Cloud Optimized GeoTIFF (COG) format specification which enables users to effeciently read these data directly off S3 while still maintaining all the benefits of distributing imagery as a GeoTIFF. These COG images contain internal overviews that GDAL can use when reading a low resolution version of the image. Each image stores a single polarization as a single band. Data are stored in linear units of power instead of logarithmic units of decibels, and saved as Float32. The NODATA value is 0, as in the original GRD product.

The data are gridded into tiles based on the Sentinel-2 20m gridding scheme. Each tile is 5490x5490 in size in a UTM zone based on the grid definition. This Sentinel-2 grid is based on the Military grid system (latest KML file). For this dataset extent (Contiguous United States), there are 993 grid tiles.

You may download the vector data we use to define the dataset extent and grid here:

Extent (CONUS)

Grid (based off Sentinel-2 MGRS grid)

Both vector files are stored in the GeoJSON format. The grid GeoJSON file has attributes that you may use to identify the grid tiles and know ahead of time the geospatial attributes of the tiled raster data (e.g., the Affine transform and projection).

Each backscatter image has the following attributes,

Attribute

Value

Description

Projection

UTM

UTM zone varies by scene

Resolution

20m

20x20m spatial resolution

Bands

1

Each polarization is stored as a separate 1-band image

Shape

5490x5490

The shape of a Sentinel-2 MGRS grid tile

No Data Value

0

Image “no data value”

Data Type

Float32

Float32 used to store backscatter as linear power ratio

Compression

Deflate

Deflate compression with predictor=3

Block Sizes

512x512

512x512 pixels per block

We also provide the local incident angle used by the Sentinel-1 Toolbox when performing terrain flattening and correction. These angle images are formatted slightly differently, and differ in the following attributes:

Attribute

Value

Description

Data Type

UInt16

Unsigned 16-bit integer

Scaling

100

Angle (degrees) is scaled and converted to UInt16 to save storage space. For example, 4500 is 45 degrees.

Data Structure

We organize the dataset on S3 in a similar manner to the layout of the Sentinel-2 L1C and L2A datasets on AWS. Data are initially split according to the grid tile and then are organized according to the year of the acquisition. All images for a given tile and date are organized within their own subdirectory, making it relatively easy to locate radar backscatter imagery and metadata if you know the grid tile and date range you are searching for.

The layout of the bucket is as follows,

s3://sentinel-s1-rtc-indigo/tiles/RTC/1/[MODE]/[MGRS UTM zone]/[MGRS latitude label]/[MGRS Grid Square ID]/[YEAR]/[SATELLITE]_[DATE]_[TILE ID]_[ORBIT DIRECTION]/[ASSET]

Where,

Path Component

Values

Description

MODE

  • IW

Only Interferometric Wide (IW) are processed

MGRS UTM Zone

  • 10 - 19

UTM Zone component of tile ID

MGRS Latitude

  • R - U

Latitude band (CONUS spans from R to U)

MGRS Grid Square ID

  • PN

The 100x100km Grid Square ID

YEAR

  • 2017

Year of the acquisition

SATELLITE

  • S1A

  • S1B

Satellite mission ID

DATE

  • 20200901

  • etc

Date of the acquisition starting time, formatted as %Y%m%d

TILE ID

  • 14TPN

  • etc

Sentinel-2 20m MGRS tile grid ID

ORBIT DIRECTION

  • ASC

  • DSC

Ascending or descending orbit direction

ASSET

  • Gamma0_VV.tif

  • Gamma0_VH.tif

  • local_incident_angle.tif

Tiled RTC Sentinel-1 Cloud Optimized GeoTIFF

For example,

s3://sentinel-s1-rtc-indigo/tiles/RTC/1/IW/14/T/PN/2020/S1A_20200801_14TPN_ASC/
s3://sentinel-s1-rtc-indigo/tiles/RTC/1/IW/14/T/PN/2020/S1A_20200801_14TPN_ASC/Gamma0_VV.tif
s3://sentinel-s1-rtc-indigo/tiles/RTC/1/IW/14/T/PN/2020/S1A_20200801_14TPN_ASC/Gamma0_VH.tif
s3://sentinel-s1-rtc-indigo/tiles/RTC/1/IW/14/T/PN/2020/S1A_20200801_14TPN_ASC/local_incident_angle.tif

These data are acquired during an ascending orbit in dual-vertical polarization for August 1st, 2020 for the tile 14TPN.