| --- |
| license: cc-by-4.0 |
| tags: |
| - aviation |
| - geospatial |
| - terrain |
| pretty_name: CommSight LZ — off-field landability fact tiles |
| --- |
| |
| # CommSight LZ — off-field landability fact tiles |
|
|
| Compressed raster **facts about ground**, built for the off-field landability layer in |
| [CommSight](https://flycommsight.com). One file per 1°×1° cell, named by the USGS 3DEP convention |
| (`n33w107` = the cell whose north-west corner is 33°N 107°W, so it spans lat 32–33, lon −107…−106). |
|
|
| > ### ⚠️ Advisory only — not for navigation |
| > These tiles describe terrain and land cover. They are **not** a survey, **not** a database of |
| > landing sites, and **not** a landing recommendation. Surface condition, fences, livestock, crops |
| > in season, wires below the charted-obstacle threshold and any current obstruction are **not |
| > modelled**. The absence of a depicted hazard is not evidence that none is there. Pilot-in-command |
| > judgment is final. |
|
|
| ## What is in a pack |
|
|
| Six `uint8` planes per 256×256 tile, plus the tile's DEM provenance byte: |
|
|
| | plane | what it is | |
| |---|---| |
| | `class` | surface class (water, wetland, developed, canopy, crop, range, barren…) | |
| | `conf` | confidence in that class, scaled by the source's own confidence band | |
| | `slope` | median slope, 0–50.8° | |
| | `rough` | detrended surface roughness (residual σ) | |
| | `hazard` | fused obstacle/hazard field from towers, roads and transmission corridors | |
| | `flags` | bitfield — charted obstacle, corridor, road buffer, water, wetland, coarse terrain | |
|
|
| **Facts, never verdicts.** Nothing here knows what aircraft is flying. Scoring happens on the |
| device, where the pilot's glide ratio and performance re-tint the same ground — so the same tile |
| means different things to a Cub and to a Malibu, and changing aircraft costs no download. |
|
|
| MBTiles/SQLite containers, z6–z13, planes raw-DEFLATE. `index.json` at the repo root is the |
| catalog: a flat `cells[]` array with bounds, size, sha256 and per-source vintages, plus `regions[]` |
| grouping cells into areas a pilot would recognise. |
|
|
| Overviews never average. Point hazards take the worst child; areal textures take the second-worst |
| of four, because plain `max` compounds up a pyramid until the map excludes everything (measured: |
| 16% → 73% between z13 and z8 on the first cell). Native resolution is untouched either way. |
|
|
| ## Coverage |
|
|
| Grows as cells are built. `index.json` is authoritative — a cell absent from it does not exist. |
| Each entry publishes `coarse_terrain_tiles`: how much of that cell had only 10 m elevation |
| available, where the ditch- and berm-scale checks **cannot run** and the score is capped instead. |
|
|
| ## Sources and attribution |
|
|
| | source | licence | |
| |---|---| |
| | USGS 3DEP elevation (1 m where published, else 1/3″) | public domain (US Gov) | |
| | USGS Annual NLCD land cover + confidence | public domain (US Gov) | |
| | USDA NASS Cropland Data Layer | public domain (US Gov) | |
| | USFWS National Wetlands Inventory | public domain (US Gov) | |
| | FAA Digital Obstacle File | public domain (US Gov) | |
| | US Census TIGER/Line roads | public domain (US Gov) | |
| | **Meta / WRI canopy height** | **CC-BY-4.0 — attribution required** | |
|
|
| Canopy height data © Meta Platforms, Inc. and World Resources Institute, used under |
| [CC-BY-4.0](https://creativecommons.org/licenses/by/4.0/). Source imagery is from 2016, so canopy |
| here is roughly a decade old and reads **low** against present-day growth. Every other input is |
| United States federal public-domain data. |
|
|
| ### No OpenStreetMap data is present in these tiles |
|
|
| Deliberately, and it is load-bearing rather than incidental. OSM is ODbL, and conflating ODbL |
| geometry into the hazard plane would make this a Derivative Database — a one-way door that could |
| compel opening data these tiles are intended to be combinable with. The hazard plane is built |
| solely from public-domain federal sources, and the build pipeline **proves** it: the planes are |
| rebuilt with the OSM artifact deleted and compared bit-for-bit. |
|
|
| ## Verifying a pack |
|
|
| Files are stored as classic Git-LFS, not Xet, because the app fetches them with a plain anonymous |
| `GET`. If you re-host these, keep it that way: |
|
|
| ```bash |
| curl -sL -o n33w107.lzpack \ |
| https://huggingface.co/datasets/SingularityUS/commsight-lz/resolve/main/cells/n33w107.lzpack |
| sqlite3 n33w107.lzpack "SELECT name, value FROM metadata WHERE name LIKE 'lz_%';" |
| ``` |
|
|
| The `sha256` in `index.json` is the authority on integrity. |
|
|
