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feat: start Aerial Imagery extension (#260)
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* feat: start Aerial Imagery extension

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dwsilk authored May 22, 2023
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64 changes: 64 additions & 0 deletions extensions/aerial-imagery/README.md
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# LINZ Aerial Imagery Extension Specification

**This is a work in progress and has not been reviewed everything is likely to
change**

- **Title**: Aerial Imagery
- **Identifier**: <https://stac.linz.govt.nz/_STAC_VERSION_/aerial-imagery/schema.json>
- **Field Name Prefix**: aerial-imagery
- **Scope**: Item, Collection
- **Extension Maturity Classification**: Work In Progress (Before proposal)

Toitū Te Whenua makes New Zealand’s publicly owned aerial imagery freely available to use under an open licence. You can access this through the [LINZ Data Service](https://data.linz.govt.nz/data/category/aerial-photos/?s=n), [LINZ Basemaps](https://basemaps.linz.govt.nz/#@-41.8899962,174.0492437,z5) or an Amazon Web Services (AWS) S3 bucket.

STAC metadata is stored in `s3://linz-imagery`, a public requester-pays bucket in the `ap-southeast-2` region, alongside the aerial imagery surveys. The STAC Catalog and Collections are maintained using a [public GitHub repository](https://github.com/linz/imagery).

The aerial imagery survey metadata that is being converted to STAC is also held in the NZ Imagery Survey Index layer on the [LINZ Data Service](https://data.linz.govt.nz/layer/95677).

For more details see
[our website](https://www.linz.govt.nz/products-services/data/types-linz-data/aerial-imagery).

- Examples:
- [Collection example](https://stac.linz.govt.nz/_STAC_VERSION_/aerial-imagery/examples/collection.json): Shows the basic usage of the
extension in a STAC Collection
- [Item example](https://stac.linz.govt.nz/_STAC_VERSION_/aerial-imagery/examples/item.json): Shows the basic usage of the extension
in a STAC Item
- [JSON Schema](https://stac.linz.govt.nz/_STAC_VERSION_/aerial-imagery/schema.json)

## STAC Collections

### [STAC Collection Fields](https://github.com/radiantearth/stac-spec/blob/v1.0.0/collection-spec/collection-spec.md)

| Field Name | Type | Description |
| ---------- | --------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------ |
| title | string | **REQUIRED**. A short descriptive one-line title for the Collection. |
| providers | [Provider Object](https://github.com/radiantearth/stac-spec/blob/v1.0.0/collection-spec/collection-spec.md#provider-object) | **REQUIRED**. A list of providers. At least one Provider with a role of each of `licensor`, `producer`, `processer` and `host` must exist. |

## STAC Items

### [STAC Item Fields](https://github.com/radiantearth/stac-spec/blob/v1.0.0-rc.1/item-spec/item-spec.md)

| Field Name | Type | Description |
| ---------- | ------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| id | string | **REQUIRED**. Provider identifier. The ID should be unique within the Collection that contains the Item. |
| geometry | [GeoJSON Geometry Object](https://tools.ietf.org/html/rfc7946#section-3.1) \| [null](https://tools.ietf.org/html/rfc7946#section-3.2) | **REQUIRED.** Defines the full footprint of the asset represented by this item, formatted according to [RFC 7946, section 3.1](https://tools.ietf.org/html/rfc7946#section-3.1). The footprint should be the default GeoJSON geometry, though additional geometries can be included. Coordinates are specified in Longitude/Latitude or Longitude/Latitude/Elevation based on [WGS 84](http://www.opengis.net/def/crs/OGC/1.3/CRS84). |
| bbox | \[number] | **REQUIRED** Bounding Box of the asset represented by this Item, formatted according to [RFC 7946, section 5](https://tools.ietf.org/html/rfc7946#section-5). |

### [STAC Item Properties](https://github.com/radiantearth/stac-spec/blob/v1.0.0/item-spec/item-spec.md#properties-object)

| Field Name | Type | Description |
| ---------- | ---- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| datetime | null | **REQUIRED**. Use `null` as `start_datetime` and `end_datetime` from [common metadata](https://github.com/radiantearth/stac-spec/blob/v1.0.0/item-spec/common-metadata.md#date-and-time-range) are to be used instead. |

#### [Common Metadata](https://github.com/radiantearth/stac-spec/blob/v1.0.0/item-spec/common-metadata.md)

| Field Name | Type | Description |
| -------------- | ------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| start_datetime | string | **REQUIRED**. The first or start date and time for the Item, in UTC. It is formatted according to [RFC 3339, section 5.6](https://tools.ietf.org/html/rfc3339#section-5.6) and [ISO 8601](https://www.iso.org/iso-8601-date-and-time-format.html). |
| end_datetime | string | **REQUIRED**. The first or start date and time for the Item, in UTC. It is formatted according to [RFC 3339, section 5.6](https://tools.ietf.org/html/rfc3339#section-5.6) and [ISO 8601](https://www.iso.org/iso-8601-date-and-time-format.html). |

#### [File Info Extension](https://github.com/stac-extensions/file/blob/v1.0.0/README.md)

| Field Name | Type | Description |
| ---------------------------------------------------------------------------------------- | ------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| [file:checksum](https://github.com/stac-extensions/file/blob/v1.0.0/README.md#checksums) | string | **REQUIRED**. Provides a way to specify file [checksums](#checksums) (e.g. BLAKE2, MD5, SHA1, SHA2, SHA3). The hashes are self-identifying hashes as described in the [Multihash specification](https://github.com/multiformats/multihash) and must be encoded as hexadecimal (base 16) string with lowercase letters. |
21 changes: 21 additions & 0 deletions extensions/aerial-imagery/examples/collection.json
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{
"type": "Collection",
"stac_version": "1.0.0",
"id": "01GHD4BHWJ4PJAS2T7M5G45JQT",
"title": "Bay of Plenty 0.2m Aerial Photos (2021-2022)",
"description": "Bay of Plenty 0.2m Rural Aerial Photos",
"license": "CC-BY-4.0",
"links": [
{ "rel": "self", "href": "./collection.json", "type": "application/json" },
{ "rel": "item", "href": "./BC40_2000_2421.json", "type": "application/json" }
],
"providers": [
{ "name": "BOPLASS", "roles": ["licensor"] },
{ "name": "AAM NZ", "roles": ["producer"] },
{ "name": "Toitū Te Whenua Land Information New Zealand", "roles": ["host", "processor"] }
],
"extent": {
"spatial": { "bbox": [[176.4620537, -38.8704907, 178.1159018, -37.5040892]] },
"temporal": { "interval": [["2021-12-01T11:00:00Z", "2022-05-05T12:00:00Z"]] }
}
}
49 changes: 49 additions & 0 deletions extensions/aerial-imagery/examples/item.json
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{
"type": "Feature",
"stac_version": "1.0.0",
"id": "BC40_2000_2421",
"links": [
{
"rel": "self",
"href": "./BC40_2000_2421.json",
"type": "application/json"
},
{
"rel": "collection",
"href": "./collection.json",
"type": "application/json"
},
{
"rel": "parent",
"href": "./collection.json",
"type": "application/json"
}
],
"assets": {
"visual": {
"href": "./BC40_2000_2421.tiff",
"type": "image/tiff; application=geotiff; profile=cloud-optimized",
"file:checksum": "12206a8fdde3e33ec42a02a7db98a57f266e0802b97070e32dcbc0f7f08b6bb57fc2"
}
},
"stac_extensions": ["https://stac-extensions.github.io/file/v2.0.0/schema.json"],
"properties": {
"start_datetime": "2021-12-01T11:00:00Z",
"end_datetime": "2022-05-05T12:00:00Z",
"datetime": null
},
"geometry": {
"type": "Polygon",
"coordinates": [
[
[177.153697, -37.5060096],
[177.1544157, -37.518955],
[177.1652507, -37.5185728],
[177.1645301, -37.5056275],
[177.153697, -37.5060096]
]
]
},
"bbox": [177.153697, -37.518955, 177.1652507, -37.5056275],
"collection": "01GHD4BHWJ4PJAS2T7M5G45JQT"
}

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