STAC Task Summary

Key Questions and Answers

1. What is the difference between STAC Items and Assets?

   Answer: Items are containers that provide metadata and structure for spatiotemporal data, while Assets are the actual data files linked to an Item (e.g., GeoTIFF, JSON, PNG).

2. How can two developers, a senior architect and a junior programmer, start formulating STACs for LA fires?

   Answer:

   • Senior Architect: Define the data model, catalog structure, metadata standards, and storage strategy.
   • Junior Programmer: Gather data, normalize it, create STAC Items and Collections, and automate data ingestion.

3. Are Items the same as Assets?

   Answer: No, Items describe and provide metadata about data, while Assets are the actual files (e.g., GeoTIFFs, metadata).

4. Can you give a brief example of a STAC Item?

   Answer: A minimal JSON example was provided.

5. Can you give a brief example of a STAC Catalog?

   Answer: A minimal JSON example was provided.

Example Code

STAC Item

{
  "type": "Feature",
  "stac_version": "1.0.0",
  "id": "fire-perimeter-2025",
  "geometry": {
    "type": "Polygon",
    "coordinates": [[[100.0, 0.0], [101.0, 0.0], [101.0, 1.0], [100.0, 1.0], [100.0, 0.0]]]
  },
  "bbox": [100.0, 0.0, 101.0, 1.0],
  "properties": {
    "datetime": "2025-01-01T12:00:00Z"
  },
  "assets": {
    "data": {
      "href": "https://example.com/fire_perimeter_2025.geojson",
      "type": "application/geo+json",
      "title": "Fire Perimeter GeoJSON"
    }
  }
}

STAC Catalog

{
  "stac_version": "1.0.0",
  "type": "Catalog",
  "id": "la-fires-catalog",
  "title": "Los Angeles Fires",
  "description": "Catalog of spatiotemporal data related to Los Angeles fires.",
  "links": [
    {
      "rel": "self",
      "href": "https://example.com/catalog.json",
      "type": "application/json"
    },
    {
      "rel": "child",
      "href": "https://example.com/collection.json",
      "type": "application/json",
      "title": "Fire Progression Data"
    }
  ]
}

Summary

Items describe spatiotemporal entities and link to Assets. Catalogs organize Items and Collections into a hierarchical structure. Examples provided for both STAC Items and Catalogs.