Scenarios

Scenarios turn a height model into a decision aid. Open them from Scenarios ▾ in the header or Tools → Scenarios.

Flood response

Water rises from a source and flows out over the terrain, filling the connected lower ground first. The flow is simulated with the shallow-water equations (the local inertial scheme used by LISFLOOD-FP, with Manning friction), so the water advances as a front, runs downhill and pools in hollows before it settles at the chosen level. In 3D the water is drawn at its real height: buildings lower than the water are submerged, and taller ones stand out of it with a visible waterline. Buildings are ranked by how soon the water reaches them, how many people they are likely to hold, and whether they house critical facilities.

1. Make sure the scene has terrain elevation: it must be georeferenced and anchored (Anchoring). Without terrain, the panel shows Needs terrain elevation.
2. Choose a Flood source:
   • Water bodies: rivers, lakes and ponds detected in the scene;
   • Chosen point: click a location on the terrain;
   • Whole scene: a uniform rise everywhere.
3. Drag Water level rise, or press Play to animate it. The water follows as a time-lapse (about 8 simulated minutes per second). The panel reports the flooded area and water depth as the water moves, and marks buildings under their roofline as submerged.
4. Optionally enable Show water on the terrain and Shade dry ground by how soon it floods.
5. Review the priority table: each building’s tier and score, with ★ marking critical facilities.

Priority score (0–100) is a weighted sum of:

• urgency: how early the building floods;
• occupancy proxy: footprint area × estimated storeys from the predicted height;
• critical facility: from OpenStreetMap, once the Facilities layer has loaded.

Buildings are grouped into Critical, High and lower tiers. The exact weights and thresholds are shown in the panel.

flowchart TB
  A[Anchored DSM] --> B[Pick flood source] --> C[Raise water level · connected fill]
  C --> S[Shallow-water flow simulation] --> D[Flooded area & depth]
  C --> E[Flood time per building]
  E --> F[Score = urgency + occupancy + facility] --> G[Priority table]

Telecom coverage

Place transmitter towers on the surface and check where the signal reaches, taking terrain, buildings and trees into account.

1. Click Add a tower. It is placed at the scene centre. Set each tower’s Height (m) and EIRP (dBm).
2. Pick a Frequency, MHz preset and an Environment, and set the Receiver height (m).
3. Enable Show coverage on the terrain to drape the coverage map.
4. Read the coverage breakdown and the list of the largest no-service patches (dead zones).
5. Click Suggest additional towers to get placements that close the biggest dead zones.

Caution

Both scenarios are planning aids, not engineering models. Flooding is a shallow-water simulation over the DEM terrain, on a grid of at most 256 cells a side, with closed scene edges and no rainfall, drainage or flood defences. Coverage is a line-of-sight and path-loss estimate. Their accuracy is bounded by the height model’s accuracy (Error analysis).