Mission viewer

Requires the viz extra (pip install "longeron[viz]").

The track/CZML synthesis this widget plays lives in longeron.analysis.mission3d.

Fly a MissionTrack on a CesiumJS globe (anywidget).

mission_viewer() renders a MissionTrack’s baked CZML document on a Cesium Viewer: a grey planned-route polyline, small waypoint pins, and a drone entity that flies the samples with an orange trail, its label following the ACTIVE STATE name through the mission. The track synthesis itself – waypoints, state-machine timelines, CZML and glTF baking – lives in longeron.analysis.mission3d: it is analysis, deterministic and testable without a browser.

The camera tracks the drone with an offset sized from the route (CZML viewFrom). Cesium’s native timeline + animation dial are the mission-playback UI (play/pause/scrub); the chrome that needs Cesium ion (base-layer picker, geocoder) stays off. Clicking the drone (or any mission entity) reports its CZML id on the picked_json trait – the same pick seam as longeron.widgets.viewer3d – and the bidirectional time trait (seconds past the track epoch) lets kernel code scrub or follow the playhead. The playing / rate / drift_s traits are the time seam’s Cesium bridge (longeron.widgets.link_time()): playing mirrors the Cesium dial (clock.shouldAnimate) both ways, rate mirrors the multiplier, and while the dial animates a kernel seek inside drift_s (scaled by the multiplier) is treated as peer integration and ignored – the bounded-drift reconciliation that keeps the clock and the dial from fighting; a paused viewer converges exactly (echo tolerance 1e-3). The stage keeps a fixed explicit height (height_px, default 480) at 98% width, so it never overflows a notebook cell or the sidebar.

No Cesium ion token is required: every imagery base is tokenless on the plain WGS84 ellipsoid. The default 'satellite' is Esri World Imagery – the keyless ArcGIS Online World_Imagery tile service, acceptable for light development/demo use with the attribution the widget’s credit bar shows (heavy or production use should bring an ArcGIS API key or a Cesium ion token instead); 'plain' draws no imagery at all – a neutral dark-slate globe on which the route, trail, and model read cleanly; 'osm' is OpenStreetMap street tiles. Passing ion_token= upgrades to Cesium World Terrain + imagery regardless of imagery.

Offline tradeoff: the front-end loads CesiumJS (~6 MB plus workers and assets) from the pinned jsDelivr CDN at view time – the same judgment as longeron.widgets.viewer3d’s three.js (~630 kB was already too big to vendor; Cesium is ~10x that, a fortiori). On an offline front-end the widget degrades to a printed notice instead of a globe, and a later re-render retries the load. This is also why there is no browser-tier test for this widget: rendering truth would hard-depend on live CDN access (see tests/test_mission3d.py).

Requires the viz extra for anywidget: pip install "longeron[viz]".

longeron.widgets.mission3d.CESIUM_BASE_URL = 'https://cdn.jsdelivr.net/npm/cesium@1.144.0/Build/Cesium/'

workers/assets/widgets resolve against this base (window.CESIUM_BASE_URL)

longeron.widgets.mission3d.CESIUM_VERSION = '1.144.0'

pinned CDN release (monthly Cesium train); bump deliberately, with the evidence capture re-run – never float a latest tag

longeron.widgets.mission3d.Imagery

the imagery bases mission_viewer accepts (all tokenless): Esri World Imagery, a neutral dark globe with no tiles at all, or OpenStreetMap streets – _IMAGERY_BASES derives from this alias, so the two cannot drift

alias of Literal[‘satellite’, ‘plain’, ‘osm’]

longeron.widgets.mission3d.mission_viewer(track, *, mesh=None, model_scale=1.0, label=None, height_px=480, imagery='satellite', ion_token='')

Fly track on a Cesium globe in the notebook.

The viewer starts paused at the track epoch with the camera tracking the drone; Cesium’s native timeline and animation dial play, pause, scrub, and re-speed the mission. Pass mesh (a longeron.analysis.geometry mesh dict) to fly the airframe’s own geometry as a glTF model at model_scale times true size, flown with the multirotor attitude (yaw along the track heading, props level in vertical phases, the track’s tilt_deg forward tilt in cruise); without a mesh the drone is a point. imagery picks the tokenless base: 'satellite' (Esri World Imagery, the default), 'plain' (a neutral dark globe, no tiles), or 'osm' (OpenStreetMap streets); ion_token upgrades to Cesium World Terrain + imagery regardless. Click the drone (or a waypoint pin) to report its CZML id on picked_json; drive or observe the playhead through the bidirectional time trait. Assign a new JSON string to czml_json to swap the mission in place.

Return type:

AnyWidget