Mission Scenario: Photogrammetry Mapping
Objective
Create a high-resolution 2D orthomosaic or 3D model of a 5-hectare construction site. The drone must maintain a consistent ground resolution (GSD) and ensure 80% frontal overlap between photos.
Vehicle Configuration
- Type: Multirotor (Quad/Hex)
- Payload: High-resolution RGB Camera (e.g., Sony A7R) pointing Nadir (straight down).
- Speed: 8 m/s (optimized for shutter speed vs. motion blur).
- Altitude: 60m AGL (Above Ground Level).
Key Concepts
- Distance Triggering: Using
DO_SET_CAM_TRIGG_DISTinstead of time intervals guarantees overlap even if the drone slows down against the wind. - Overshoot: The drone flies past the edge of the survey area before turning. This ensures the vehicle is stable and moving at constant velocity before entering the next capture leg.
Mission Plan
| Seq | Command | Parameters | Description |
|---|---|---|---|
| 1 | NAV_TAKEOFF |
Alt: 30m | Climb safely above obstacles before navigating. |
| 2 | DO_CHANGE_SPEED |
Speed: 8 m/s | Set survey cruise speed. |
| 3 | DO_MOUNT_CONTROL |
Pitch: -90, Roll: 0, Yaw: 0 | Point camera straight down (Nadir). |
| 4 | NAV_WAYPOINT |
Lat/Lon: [Start of Grid] | Fly to the first survey point. |
| 5 | DO_SET_CAM_TRIGG_DIST |
Dist: 18.5m | Start capturing a photo every 18.5 meters (calculated for 80% overlap). |
| 6 | NAV_WAYPOINT |
Lat/Lon: [End of Leg 1] | Fly the first transect. |
| 7 | NAV_WAYPOINT |
Lat/Lon: [Turn Point] | Turn 90 degrees to next lane. |
| 8 | NAV_WAYPOINT |
Lat/Lon: [Start of Leg 2] | Align for return pass. |
| 9 | NAV_WAYPOINT |
Lat/Lon: [End of Leg 2] | Fly the second transect. |
| ... | ... | ... | Repeat pattern... |
| 50 | DO_SET_CAM_TRIGG_DIST |
Dist: 0 | Stop capturing photos to save storage/processing time. |
| 51 | DO_MOUNT_CONTROL |
Pitch: 0, Roll: 0, Yaw: 0 | Retract/Level gimbal for landing. |
| 52 | NAV_RETURN_TO_LAUNCH |
- | Return home and auto-land. |
Pro-Tips
- Terrain Following: If the site is hilly, use
TERRAINframe for all waypoints to ensure the GSD (pixel size) remains constant across the entire map. - Shutter Priority: Set your camera to Shutter Priority (Tv) mode with at least 1/1000s shutter speed to eliminate motion blur at 8 m/s.