Started common metadata page

collection-spec/examples/landsat-item.json

@@ -3,7 +3,6 @@
     "stac_extensions": [
         "commons",
         "eo",
-        "instrument",
         "https://example.com/stac/landsat-extension/1.0/schema.json"
     ],
     "id": "LC08_L1TP_107018_20181001_20181001_01_RT",

extensions/README.md

@@ -53,7 +53,6 @@ An extension can add new fields to STAC entities (content extension), or can add
 | [Data Cube](datacube/README.md) (`cube`)                     | Item, Collection | Data Cube related metadata, especially to describe their dimensions. | *Proposal* |
 | [Datetime Range](datetime-range/README.md) (-)               | Item             | An extension to provide datetime ranges with a start and an end datetime stamp in a consistent way. | *Proposal* |
 | [EO](eo/README.md) (`eo`)                                    | Item             | Covers electro-optical data that represents a snapshot of the earth for a single date and time. It could consist of multiple spectral bands, for example visible bands, infrared bands, red edge bands and panchromatic bands. The extension provides common fields like bands, cloud cover, gsd and more. | *Pilot* |
-| [Instrument](instrument/README.md) (-)                       | Item             | Adds metadata specifying a platform and instrument used in a data collection mission. | *Proposal* |
 | [Label](label/README.md) (`label`)                           | Item             | Items that relate labeled AOIs with source imagery | *Proposal* |
 | [Point Cloud](pointcloud/README.md) (`pc`)                   | Item             | Provides a way to describe point cloud datasets. The point clouds can come from either active or passive sensors, and data is frequently acquired using tools such as LiDAR or coincidence-matched imagery. | *Proposal* |
 | [SAR](sar/README.md) (`sar`)                                 | Item             | Covers synthetic-aperture radar data that represents a snapshot of the earth for a single date and time. | *Proposal* |

extensions/commons/README.md

@@ -76,7 +76,7 @@ An incomplete item:
 ```
 {
   "stac_version": "0.8.1",
-  "stac_extensions": ["commons", "eo", "instrument", "sat"],
+  "stac_extensions": ["commons", "eo", "sat"],
   "type": "Feature",
   "id": "LC08_L1TP_107018_20181001_20181001_01_RT",
   "bbox": [...],
@@ -98,7 +98,7 @@ The merged Item then looks like this:
 ```
 {
   "stac_version": "0.8.1",
-  "stac_extensions": ["eo", "instrument", "sat"],
+  "stac_extensions": ["eo", "sat"],
   "type": "Feature",
   "id": "LC08_L1TP_107018_20181001_20181001_01_RT",
   "bbox": [...],

extensions/commons/examples/landsat-item.json

@@ -3,7 +3,6 @@
     "stac_extensions": [
         "commons",
         "eo",
-        "instrument",
         "sat",
         "https://example.com/stac/landsat-extension/1.0/schema.json"
     ],

extensions/eo/README.md

@@ -18,7 +18,7 @@ A lot of EO data will have common metadata across many Items.
 It is not necessary, but recommended to use the [Commons extension](../commons/README.md)
 (see chapter "Placing common fields in Collections").
 
-If the data has been collected by a satellite, it is strongly recommended to use the [`sat` extension](../sat/README.md), which in turn requires the [`instrument` extension](../instrument/README.md). If the data has been collected on an airborne platform is is strongly recommended to use the [`instrument` extension](../instrument/README.md).
+If the data has been collected by a satellite, it is strongly recommended to use the [`sat` extension](../sat/README.md), which in turn requires the [Instrument Fields](../item-spec/common-metadata.md#instrument). If the data has been collected on an airborne platform is is strongly recommended to use the [Instrument Fields](../item-spec/common-metadata.md#instrument).
 
 - [Example (Landsat 8)](examples/example-landsat8.json)
 - [JSON Schema](json-schema/schema.json)
@@ -223,7 +223,6 @@ the eo:bands portion is still being fleshed out.
 The [extensions page](../README.md) gives an overview about related extensions. Of particular relevance to EO data:
 
 * the [Sat Extension Specification](../sat/README.md) to describe SAR data collected from a satellite.
-* the [Instrument Extension Specification](../instrument/README.md) is required when using the EO extension, which contains fields about the sensor and platform used to collect the data. It is required when using the Sat extension.
 
 ### Placing common fields in Collections
 A lot of EO data will have common metadata across many Items. It is not necessary, but recommended	

extensions/eo/examples/example-landsat8.json

@@ -2,7 +2,6 @@
     "stac_version": "0.9.0",
     "stac_extensions": [
       "eo",
-      "instrument",
       "https://example.com/stac/landsat-extension/1.0/schema.json"
     ],
     "id": "LC08_L1TP_107018_20181001_20181001_01_RT",

extensions/sar/README.md

@@ -7,7 +7,7 @@ SAR data is considered to be data that represents a snapshot of the earth for a
 
 It is not necessary, but recommended to use the [Commons extension](../commons/README.md) (see chapter "Placing common fields in Collections").
 
-If the data has been collected by a satellite, it is strongly recommended to use the [`sat` extension](../sat/README.md), which in turn requires the [`instrument` extension](../instrument/README.md). If the data has been collected on an airborne platform is is strongly recommended to use the [`instrument` extension](../instrument/README.md).
+If the data has been collected by a satellite, it is strongly recommended to use the [`sat` extension](../sat/README.md), which in turn requires the [Instrument Fields](../item-spec/common-metadata.md#instrument). If the data has been collected on an airborne platform is is strongly recommended to use the [Instrument Fields](../item-spec/common-metadata.md#instrument).
 
 - [Examples](examples/) (for example [Sentinel-1](examples/sentinel1.json) and [Envisat](examples/envisat.json))
 - [JSON Schema](json-schema/schema.json)
@@ -84,7 +84,6 @@ The [extensions page](../README.md) gives an overview about related extensions.
 
 * the [Datetime Range Extension Specification](../datetime-range/README.md) to describe frame start and end time.
 * the [Sat Extension Specification](../sat/README.md) to describe SAR data collected from a satellite.
-* the [Instrument Extension Specification](../instrument/README.md) which contains fields about the sensor and platform used to collect the data. The Instrument extension is required when using the Sat extension.
 
 ### Placing common fields in Collections
 A lot of SAR data will have common metadata across many Items. It is not necessary, but recommended	

extensions/sar/examples/envisat.json

@@ -3,8 +3,7 @@
   "stac_extensions": [
     "datetime-range",
     "sat",
-    "sar",
-    "instrument"
+    "sar"
   ],
   "id": "ASA_GM1_1PNPDE20090520_023957_000001022079_00118_37747_3607",
   "type": "Feature",

extensions/sar/examples/sentinel1.json

@@ -4,8 +4,7 @@
     "checksum",
     "datetime-range",
     "sar",
-    "sat",
-    "instrument"
+    "sat"
   ],
   "id": "S1A_EW_GRDM_1SSH_20181103T235855_20181103T235955_024430_02AD5D_5616",
   "type": "Feature",

extensions/sat/README.md

@@ -4,7 +4,7 @@
 
 This document explains the fields of the Satellite Extension to a STAC Item. Sat adds metadata related to a satellite that carries an instrument for collecting data. It will often be combined with other extensions that describe the actual data, such as the `eo` or `sar` extensions. In many instances, satellite data will share common properties about the spacecraft across all of the Items. It is not necessary, but recommended to place common fields in [STAC Collections](../../collection-spec/collection-spec.md#common-fields-and-standalone-collections).
 
-The Satellite extension requires the (Instrument extension)[../instrument/README.md].
+The Satellite extension requires the [Instrument Fields](../item-spec/common-metadata.md#instrument).
 
 - [Example (Landsat 8)](examples/example-landsat8.json)
 - [JSON Schema](json-schema/schema.json)
@@ -39,8 +39,7 @@ Example:
 {
   "stac_version": "0.9.0",
   "stac_extensions": [
-    "sat",
-    "instrument"
+    "sat"
   ],
   "id": "20171110",
   "type": "Feature",
@@ -66,6 +65,4 @@ Example:
 
 ## Extensions
 
-The [extensions page](../README.md) gives an overview about related extensions. Of particular relevance to sat data:
-
-* the [Instrument Extension Specification](../instrument/README.md), required when using the `sat` extension, which contains fields about the sensor and platform used to collect the data.
+The [extensions page](../README.md) gives an overview about related extensions. Of particular relevance to sat data.

extensions/sat/examples/example-landsat8.json

@@ -1,8 +1,7 @@
 {
     "stac_version": "0.9.0",
     "stac_extensions": [
-      "sat",
-      "instrument"
+      "sat"
     ],
     "id": "LC08_L1TP_107018_20181001",
     "collection": "landsat-8-l1",

item-spec/README.md

@@ -11,6 +11,9 @@ endpoints of a `/search` endpoint.
 **Item Specification:** The main definition of the STAC Item specification is in 
 *[item-spec.md](item-spec.md)*. It includes an overview and an in-depth explanation of the fields.
 
+**Common Metadata:** A set of commonly used metadata fields for STAC Items is listed in 
+*[common-metadata.md](common-metadata.md)*.
+
 **ItemCollection Specification:** The main definition of the STAC ItemCollection specification is in 
 *[itemcollection-spec.md](itemcollection-spec.md)*. It includes an overview and an in-depth explanation of the fields.