nz-stac · git:20261008.c9d8874 · 2026-10-08 · sha256 6f9469c2ce3d4756
nz-stac git:20261008.c9d8874A
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--- name: nz-stac description: "Find LINZ elevation and aerial imagery collections and COG tiles from public NZ STAC catalogues. Use for DEM/DSM, RGB/infrared footprints, bbox tile searches and elevation point sampling guidance." license: MIT compatibility: "Requires Python 3.10+ and network access for live data" metadata: thecolab.category: "geospatial" thecolab.source_owner: "Toitū Te Whenua Land Information New Zealand" thecolab.source_type: "official" thecolab.auth: "none" thecolab.access_mode: "public-STAC-HTTPS" thecolab.data_class: "public" thecolab.writes: "false" thecolab.browser: "false" thecolab.risk: "low" thecolab.cache_ttl: "none" thecolab.schema_version: "1" thecolab.skill_type: "public-api" thecolab.pack: "nz-public-data" thecolab.source_url: "https://nz-elevation.s3.ap-southeast-2.amazonaws.com/catalog.json" thecolab.allowed_domains: "nz-elevation.s3.ap-southeast-2.amazonaws.com,nz-imagery.s3.ap-southeast-2.amazonaws.com" thecolab.last_verified: "2026-10-08" thecolab.health: "healthy" thecolab.maintainer: "@adam91holt" --- # NZ STAC Find datasets and Cloud Optimised GeoTIFF (COG) tile URLs in LINZ's public `nz-elevation` and `nz-imagery` AWS buckets, hosted in `ap-southeast-2`. Python 3.10+, stdlib only; no AWS credentials, boto3, or LINZ Data Service key. ## Workflow 1. Run `collections` with the bucket kind and optional region. Copy the returned `collection` selector (kind plus published path), or use its HTTPS `collection.json` URL. `info` returns the upstream STAC id and full metadata. 2. Check capture interval, product and resolution with `info`. DEM represents terrain; DSM includes surface features. Use the source capture dates for freshness, rather than its processing/update date. 3. Use a small WGS84 bbox to find tiles. `--format geojson` emits a FeatureCollection of the actual STAC footprints. Assets are public HTTPS COG URLs. The helper fetches bounded JSON metadata only, never raster files. 4. For a terrain point, use a DEM collection with `point`. It returns `sampling_status=sampling_required`, `elevation=null`, the tile URL and a `gdallocationinfo` one-liner. Run that command with GDAL installed to sample remotely by HTTP range reads. Check nodata and the source vertical datum. The stdlib helper does not decode compressed GeoTIFFs or report an invented elevation. A tile footprint may contain nodata. ## Commands Run from the repository root, or use an absolute path to `scripts/cli.py`. ```bash python3 skills/nz-stac/scripts/cli.py collections --kind elevation --region auckland --json python3 skills/nz-stac/scripts/cli.py collections --kind imagery --region auckland --json python3 skills/nz-stac/scripts/cli.py info elevation:auckland/auckland-part-1_2024/dem_1m/2193 --json python3 skills/nz-stac/scripts/cli.py tiles elevation:auckland/auckland-part-1_2024/dsm_1m/2193 --bbox 174.715,-36.905,174.725,-36.895 --json python3 skills/nz-stac/scripts/cli.py tiles elevation:auckland/auckland-north_2016-2018/dem_1m/2193 --bbox 174.715,-36.905,174.725,-36.895 --format geojson python3 skills/nz-stac/scripts/cli.py tiles imagery:auckland/auckland_2024_0.075m/rgb/2193 --bbox 174.715,-36.905,174.725,-36.895 --format geojson python3 skills/nz-stac/scripts/cli.py tiles imagery:auckland/auckland_2024_0.075m/rgbnir/2193 --bbox 174.715,-36.905,174.725,-36.895 --limit 5 --json python3 skills/nz-stac/scripts/cli.py point --lon 174.72 --lat -36.9 --collection elevation:auckland/auckland-part-1_2024/dem_1m/2193 --json ``` Every data command supports `--json`; `tiles` and `point` also support `--format geojson`. Human output is the default. ## Bounds and interpretation - `--bbox` is `minLon,minLat,maxLon,maxLat`. Longitude comes first. Tile search supports mainland NZ Topo50 tile names in EPSG:2193; unsupported grids fail clearly. Chatham Islands need a different CRS. - Collections default to 100 records, capped at 200 per request. Use `--offset` and `--limit` for another slice. `matched` is the catalogue count after region filtering. Listings derive year, resolution and product from published names and paths; licence is null until `info` or tile metadata supplies it. - Tile results default to 20, capped at 50. At most 100 nearby item JSON files are candidates; a larger bbox fails with a request to narrow it. `truncated` means at least one additional matching footprint exists. Results include `candidates` and `items_inspected`; there is no unbounded item crawl. - JSON envelopes and records carry `source_url`, `publisher`, `licence`, `retrieved_at` (UTC) and `latest_data` (capture end, or the catalogue title's stated year range). Unknown metadata stays null. - `point` returns all discovered touching tiles up to four, with an explicit truncation flag. `no_tile` means no intersecting tile in that collection. It does not mean the location has no elevation in other collections. Read [references/source-notes.md](references/source-notes.md) for the static STAC schema, tile-grid method, exact Auckland selectors and source limits. Verify the skill with `scripts/test_contract.py` (deterministic fixtures) and `scripts/smoke_test.py` (bounded live Auckland probes and one 16-byte COG range).