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emmanuelmathotemmanuelmathot
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simplified swath descriptiomn
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‎.vscode/settings.json

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{
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"jira-plugin.workingProject": ""
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}

‎README.md

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## Item Properties or Asset Fields
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| Field Name | Type | Description |
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| --------------------------- | ------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
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| sar:instrument_mode | string | **REQUIRED.** The name of the sensor acquisition mode that is commonly used. This should be the short name, if available. For example, `WV` for "Wave mode" of Sentinel-1 and Envisat ASAR satellites. |
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| sar:frequency_band | string | **REQUIRED.** The common name for the frequency band to make it easier to search for bands across instruments. See section "Common Frequency Band Names" for a list of accepted names. |
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| sar:center_frequency | number | The center frequency of the instrument, in gigahertz (GHz). |
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| sar:polarizations | \[string] | **REQUIRED.** Any combination of polarizations. |
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| sar:product_type | string | ***DEPRECATED** in favor of [`product:type`](https://github.com/stac-extensions/product).* The product type, for example `SSC`, `MGD`, or `SGC` |
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| sar:resolution_range | number | The range resolution, which is the maximum ability to distinguish two adjacent targets perpendicular to the flight path, in meters (m). |
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| sar:resolution_azimuth | number | The azimuth resolution, which is the maximum ability to distinguish two adjacent targets parallel to the flight path, in meters (m). |
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| sar:pixel_spacing_range | number | The range pixel spacing, which is the distance between adjacent pixels perpendicular to the flight path, in meters (m). Strongly RECOMMENDED to be specified for products of type `GRD`. |
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| sar:pixel_spacing_azimuth | number | The azimuth pixel spacing, which is the distance between adjacent pixels parallel to the flight path, in meters (m). Strongly RECOMMENDED to be specified for products of type `GRD`. |
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| sar:looks_range | number | Number of range looks, which is the number of groups of signal samples (looks) perpendicular to the flight path. |
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| sar:looks_azimuth | number | Number of azimuth looks, which is the number of groups of signal samples (looks) parallel to the flight path. |
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| sar:looks_equivalent_number | number | The equivalent number of looks (ENL). |
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| sar:observation_direction | string | Antenna pointing direction relative to the flight trajectory of the satellite, either `left` or `right`. |
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| sar:relative_burst | number | Identification number that uniquely identifies a burst cycle within each repeat cycle. |
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| sar:swath | \[[Beam Object](#beam-object)] | Composition of the swath of the SAR acquisition. |
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| Field Name | Type | Description |
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| --------------------------- | --------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
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| sar:instrument_mode | string | **REQUIRED.** The name of the sensor acquisition mode that is commonly used. This should be the short name, if available. For example, `WV` for "Wave mode" of Sentinel-1 and Envisat ASAR satellites. |
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| sar:frequency_band | string | **REQUIRED.** The common name for the frequency band to make it easier to search for bands across instruments. See section "Common Frequency Band Names" for a list of accepted names. |
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| sar:center_frequency | number | The center frequency of the instrument, in gigahertz (GHz). |
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| sar:polarizations | \[string] | **REQUIRED.** Any combination of polarizations. |
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| sar:product_type | string | ***DEPRECATED** in favor of [`product:type`](https://github.com/stac-extensions/product).* The product type, for example `SSC`, `MGD`, or `SGC` |
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| sar:resolution_range | number | The range resolution, which is the maximum ability to distinguish two adjacent targets perpendicular to the flight path, in meters (m). |
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| sar:resolution_azimuth | number | The azimuth resolution, which is the maximum ability to distinguish two adjacent targets parallel to the flight path, in meters (m). |
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| sar:pixel_spacing_range | number | The range pixel spacing, which is the distance between adjacent pixels perpendicular to the flight path, in meters (m). Strongly RECOMMENDED to be specified for products of type `GRD`. |
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| sar:pixel_spacing_azimuth | number | The azimuth pixel spacing, which is the distance between adjacent pixels parallel to the flight path, in meters (m). Strongly RECOMMENDED to be specified for products of type `GRD`. |
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| sar:looks_range | number | Number of range looks, which is the number of groups of signal samples (looks) perpendicular to the flight path. |
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| sar:looks_azimuth | number | Number of azimuth looks, which is the number of groups of signal samples (looks) parallel to the flight path. |
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| sar:looks_equivalent_number | number | The equivalent number of looks (ENL). |
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| sar:observation_direction | string | Antenna pointing direction relative to the flight trajectory of the satellite, either `left` or `right`. |
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| sar:relative_burst | number | Identification number that uniquely identifies a burst cycle within each repeat cycle. |
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| sar:beam_ids | \[string] | Composition of the swath of the SAR acquision referencing the beam identifiers. |
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**Note:** In this specification *range* values are meant to be measured perpendicular to the flight path and *azimuth* values
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are meant to be measured parallel to the flight path.
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**Important:** In the `properties` of a STAC Item `sar:polarizations` must be a set with unique elements.
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In assets `sar:polarizations` can contain duplicate elements and, if possible, the polarizations must appear in the same order as in the file.
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### Beam Object
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The beam object is used to describe the subswaths of a SAR acquisition.
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According to the instrument mode defined in `sar:instrument_mode`, the `sar:swath` is composed of one or more beams.
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| Field Name | Type | Description |
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| -------------- | --------------------- | -------------------------------------------------------------------------------------- |
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| id | string | **REQUIRED.** The unique identifier of the beam. It can be the subswath identifier |
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| relative_burst | number | Identification number that uniquely identifies a burst cycle within each repeat cycle. |
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| polarizations | \[string] | Any combination of polarizations. |
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As every beam is a specific view in the acquisition, the object can also contain additional fields from the [View extension](https://github.com/stac-extensions/view).
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> \[!NOTE]
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> If the value of a field repeats for all beams, it is recommended to include it only in the parent scope, i.e. usually in the Item Properties.
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Examples of a `sar:swath` field for sentinel-1 IW mode:
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```json
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"sar:relative_burst": 541,
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"sar:polarizations": ["VV", "VH"],
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"sar:swath": [
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{
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"id": "IW1",
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"view:off_nadir": 28.3,
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"view:incident_angle": 32.1
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},
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{
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"id": "IW2",
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"view:off_nadir": 33.3,
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"view:incident_angle": 37.1
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},
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{
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"id": "IW3",
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"view:off_nadir": 38.3,
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"view:incident_angle": 42.1
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}
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]
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```
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#### sar:beam_ids
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The `sar:beam_ids` field is used to reference the beam identifiers of the SAR acquisition. According to the mission and the sensor mode,
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the beam identifiers can be used to identify the composition of the swath of the SAR acquisition.
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The beam identifiers are usually provided in the metadata of the SAR data.
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### Common Frequency Band Names
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‎examples/sentinel-1-grd-ew.json

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"sar:looks_equivalent_number": 2.7,
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"sar:frequency_band": "C",
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"sar:center_frequency": 5.405,
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"sar:swath": [
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{
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"id": "EW",
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"polarizations": [
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"HH"
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],
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"view:incident_angle": 40.1
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}
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"sar:beam_ids": [
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"EW"
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],
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"product:type": "GRD"
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},

‎examples/sentinel-1-grd-s4.json

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"processing:datetime": "2024-05-31T11:25:04.541000+00:00",
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"sar:instrument_mode": "SM",
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"processing:level": "L1",
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"sar:swath": [
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{
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"id": "S6"
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}
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"sar:beam_ids": [
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"S6"
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],
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"processing:facility": "Production Service-SERCO",
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"processing:version": "003.71",

‎examples/sentinel-1-slc-iw.json

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"processing:datetime": "2024-06-18T18:24:17.837861+00:00",
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"sar:instrument_mode": "IW",
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"processing:level": "L1",
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"sar:swath": [
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{
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"id": "IW1",
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"relative_burst": 541,
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"polarizations": [
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"VV",
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"VH"
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],
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"view:incident_angle": 32.1
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},
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{
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"id": "IW2",
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"view:incident_angle": 34.1
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},
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{
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"id": "IW3",
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"view:incident_angle": 36.1
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}
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"sar:beam_ids": [
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"IW1",
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"IW2",
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"IW3"
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],
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"processing:facility": "Production Service-SERCO",
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"processor:version": "003.80",

‎json-schema/schema.json

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"right"
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]
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},
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"sar:swath": {
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"title": "Swath",
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"sar:beam_ids": {
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"title": "Beam identifiers",
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"type": "array",
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"items": {
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"$ref": "#/definitions/beam"
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"type": "string"
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}
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}
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},
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},
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"additionalProperties": false
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},
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"beam": {
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"anyOf": [
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{
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"type": "object",
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"properties": {
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"id": {
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"title": "Beam identification",
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"type": "string",
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"minLength": 1
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},
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"relative_burst": {
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"title": "Relative burst identificator",
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"type": "integer",
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"minimum": 0
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},
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"polarizations": {
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"title": "Polarizations",
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"type": "array",
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"minItems": 1,
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"items": {
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"$ref": "#/definitions/polarizations"
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}
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}
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},
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"additionalProperties": true
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},
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{
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"$ref": "https://stac-extensions.github.io/view/v1.0.0/schema.json#/definitions/fields",
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"additionalProperties": true
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},
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{
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"required": [
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"id"
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]
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}
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]
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},
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"polarizations": {
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"type": "string",
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"enum": [

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