Line-of-Sight and Area-of-Sight terrain analysis#122
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Adds a new "Line of Sight" entry to the Measure menu. After placing an observer with the first click, the LoS recomputes on every pointermove against the Mapbox-RGB terrain tile source and renders the visible segment in green, the blocked segment as a dashed red line and the first blocker as a red diamond. Distance, eye-height delta and first-blocker distance are shown in the OSD. Range is clamped to 10 km (clip marker drawn at the cap); the second click finalises the LoS and leaves it on the map, so multiple Line-of-Sights can coexist in a session. Earth curvature and atmospheric refraction (k=0.13) are applied unconditionally to keep results realistic at the relevant distances. The command is gated on terrain availability and WebGL2 support (the latter is a prerequisite for the planned Area-of-Sight feature and is checked here for consistency). Observer/target heights default to 1.70 m AGL; an editor for these plus persistence will follow in a separate change.
Adds a LOS scope (los:{uuid}) to the id catalogue and rewires the
line-of-sight module to be store-driven. Finalised LoS results are
written to the store, restored on app start, and rebuilt incrementally
on subsequent put/del operations.
The in-progress (live-preview) overlay is unchanged. On finalisation
the live features are handed over directly to the persistent map so
there is no flicker, and a fresh losId is inserted into the store. A
small race-safe initial-load path waits for a terrain layer to be
available before rendering the persisted set.
Heights are still fixed to the 1.70 m defaults; the per-feature
height editor will land alongside selection support in a separate
change.
Selecting a finalised LoS on the map (click) now opens a Properties panel with editable observer/target height fields and a read-only distance display. Edits flow through store.update, our batch handler detects the change and rebuilds the visual representation; the existing clipboard-delete pipeline removes a selected LoS without any extra wiring. All sub-features of a LoS (observer point, visible/blocked segments, blocker diamond, clip marker) carry the same losId as OpenLayers feature id, so a click on any of them selects the whole document. The LoS layer is tagged selectable; the map-wide Select interaction is suspended while the placement tool is live so the first/second click never doubles as a feature select. Multi-select shows M/V in the height fields and accepts a value to apply to all selected LoS at once, mirroring how the other property panels behave.
- ElevationService samples at a data-driven analysis zoom (finest zoom resolving <= 15 m/cell) instead of the current view zoom: LoS and elevation profile results no longer change with zoom or after reload - promise-based tile cache deduplicates concurrent downloads; tiles are decoded once into Float32 elevations - profileAlongLine fetches required tiles in parallel, then samples synchronously - getGrid(extent) stitches a tile-aligned Float32 elevation grid (foundation for Area-of-Sight), coarsening zoom to fit a cell budget - drop the WebGL2 gate from the LoS command (LoS is CPU sampling only)
- R2 viewshed engine: WebGPU compute shader (one thread per ray), 10 km @ 10 m in single-digit ms; viewshedCPU as reference and fallback when no GPU adapter is available - tool follows the cursor with a live preview (latest-wins), click places the observer and persists the document in the aos: scope - visibility mask rendered as circular raster overlay (ImageCanvas), green/red, no-data cells stay transparent and never block - selectable observer point with properties panel for radius (default 2500 m, max 10 km) and observer/target heights; changes recompute - map clicks no longer deselect LoS/AoS results
LoS and AoS documents are now plain GeoJSON features flowing through featureSource — one feature per document, like measure. This replaces the parallel rendering paths (private layers, own store sync, multiple OL features sharing one id) and brings the standard machinery for free: delete, undo, hide/show, lock, vertex modify and selection. - LoS: LineString observer→target; the async sight-line analysis lives in the style orchestrator (ol/style/los.js) — renders as pending line until the profile arrives, recomputes on geometry/height changes and once terrain becomes available (bridge: ol/style/losCompute.js) - AoS: Point observer with radius/height properties; observer point and radius rim are pipeline styles (ol/style/aos.js), the visibility raster stays in the interaction and now mirrors hidden state (including temporary reveal while highlighted in search) - sidebar/search: options/documents handlers for both scopes with name, distance/radius description, rename and tagging - properties panels operate on GeoJSON properties - pre-pipeline documents are migrated to GeoJSON on startup
- LoS: arrow up/down adjusts observer height, shift+arrows target height while placing; live preview recomputes, values shown in OSD - AoS: arrow up/down adjusts radius (250 m steps), shift/alt+arrows observer/target height; preview recomputes on change - Escape cancels an active placement - last-used values persist per project (session store) and become the defaults for the next placement; placed objects remain editable via the properties panel
getTileGrid() returns null until a TileJSON source has fetched its metadata. setSource treated "terrain layer present" as "terrain ready" and the AoS initial load crashed on the null tile grid at startup. - setSource returns false while the tile grid is not available yet - new onTerrainReady(map, attempt) retries when a layer is added AND when a pending source finishes loading; LoS/AoS use it for computer registration and initial document rendering - getGrid/profileAlongLine/elevationAt guard against a missing grid
The emitter dispatches handlers via setImmediate, so the OSD clear from idle tools' command/draw/cancel resets landed after the freshly shown placement hint and erased it — the hint only reappeared after the first arrow-key press. - reset() clears the OSD only when the tool was actually active - the hint is re-asserted on pointer move (LoS placing phase, AoS preview) so it survives any remaining dispatch-order race
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Summary
Adds two terrain-analysis tools: Line-of-Sight (observer→target sight line with blocker detection) and Area-of-Sight (real-time viewshed). Both are backed by a reworked elevation service that samples deterministically from Mapbox-Terrain-RGB tiles, and both integrate into the standard feature pipeline like measurements.
The AoS engine runs the R2 viewshed algorithm as a WebGPU compute shader — one thread per ray — computing a 10 km radius at 10 m resolution in single-digit milliseconds, so the viewshed follows the cursor in real time during placement (benchmarked against single/multi-threaded CPU and a naive WebGL2 fragment shader; the CPU implementation remains as reference and fallback).
Changes
getGrid(extent)stitches tile-aligned elevation grids; handles TileJSON sources that are still loading their metadatafeatureSource— delete, undo, hide/show, lock, vertex modify (dragging endpoints recomputes live) and selection come from the standard machinery; pre-pipeline documents are migrated on startup