Introduction
For more information, please read the block description.
Block type: PROCESSING
This block provides a SNAP polarimetric processing workflow that is applied on SAR scenes in SAFE format. The SNAP block takes a Level 1C GRD image and generates a product ready for analysis by using a median filter for speckle filtering, creating a land-sea mask, and converting the image to a GeoTIFF format.
Supported parameters
bbox
: The bounding box to use as an AOI. Will clip to scenes that intersect with this box. Use onlybbox
orintersects
orcontains
.intersects
: A GeoJSON geometry to use as an AOI. Will clip to scenes that intersect with this geometry. Use onlybbox
orintersects
orcontains
.contains
: A GeoJSON geometry to use as an AOI. Will clip to scenes that intersect with this geometry. Use onlybbox
orintersects
orcontains
.polarisations
: Requested polarisations, either one and only one of:["VV","VH"]
,["HH", "HV"]
,["VV"]
,["VH"]
,["HV"]
or["HH"]
. The operation will fail and give a corresponding error message if the requested polarization is not avialble in the input image to SNAP.mask
: It applies a masks for eitherland
orsea
. Use one and only one, you cannot chose both.tcorrection
: It applies Range Doppler Terrain Correction based on a suitable Digital Elevation Model (DEM).clip_to_aoi
: When set totrue
, the AOI specified viabbox
, orcontains
, orintersect
for the previous data block in the workflow will first be clipped and then processed. Please note that by default this parameter is set tofalse
which means that the full scene will be processed.calibration_band
: It applies calibration to provide imagery in which the pixel values can be directly related to the radar backscatter of the scene. The default option usingSigma Nought
for calibration. Other available options areBeta Nought
andGamma Nought
.speckle_filter
: It applies Lee Sigma filter to remove speckle noise from the image. Please note that by default this parameter is set totrue
.linear_to_db
: It converst the pixel intensity to normalised radar cross-section measured in decibel (dB) units. Please note that by default this parameter is set totrue
.
Example block parameters using the Sentinel-1 L1C GRD Full Scene block as data source which is processed via SNAP after clipping it to the given AOI. The processing consists here of Range Doppler Terrain correction (tcorrection
set to true
) and a Land mask (land
set to true
).
{
"sobloo-s1-grd-fullscene:1": {
"bbox": [
13.358345031738283,
52.480689337378706,
13.395252227783203,
52.507654123207665
],
"ids": null,
"time": "2018-01-01T00:00:00+00:00/2019-12-31T23:59:59+00:00",
"limit": 1,
"time_series": null,
"orbit_direction": null,
"acquisition_mode": null
},
"snap-polarimetric:1": {
"bbox": [
13.358345031738283,
52.480689337378706,
13.395252227783203,
52.507654123207665
],
"mask": null,
"contains": null,
"intersects": null,
"clip_to_aoi": true,
"tcorrection": true,
"linear_to_db": true,
"polarisations": [
"VV"
],
"speckle_filter": true,
"calibration_band": [
"sigma"
]
}
}
Output format
The block outputs a GeoTIFF file. For each chosen polarization, a separate band will be generated in the output file. For instance, if both VV
and VH
polarizations are chosen, the output will be a single GeoTIFF with two bands, one for VV
and one for VH
polarization.
Download example output
You can create example output to use when testing processing blocks built to work with this data by running the block in a workflow via the console, and downloading the results in the job overview.
Capabilities
Input
raster
up42_standard | |
---|---|
bands | {
"or": [
[
"HH",
"HV",
"alpha"
],
[
"VV",
"VH",
"alpha"
],
[
"HH",
"alpha"
],
[
"VV",
"alpha"
]
]
} |
dtype | uint16 |
format | SAFE |
sensor | Sentinel1GRD |
resolution | 10 |
processing_level | l1 |
Output
raster
up42_standard | |
---|---|
bands | > (propagated) |
dtype | {
"or": [
"uint16",
"float"
]
} |
format | GTiff |
sensor | > (propagated) |
resolution | > (propagated) |
processing_level | > (propagated) |