FLI-MAP is a helicopter and fixed wing mounted LiDAR system designed for acquiring terrain features with high detail and high accuracy. The airborne system consists of the following components:
- Eye-safe laser scanner
- 150.000 – 200.000 – 250.000 pulses per second
- Up to 4 returns per pulse
- 60º scan angle
- 1000 pulses per scan
- 150 – 250 scans per second
- Range accuracy 1 cm (1 sigma)
- 2 Trimble L1/L2 GPS receivers
- 10 Hz positioning
- Omnistar dGPS for real-time sub-meter navigation
- Applanix PosAV V5 INS
- 200 Hz IMU data sampling
- high resolution dual and single mapping camera's with 16 Megapixel
- high resolution forward looking photo camera
- forward and down looking video cameras
- line scan RGB camera tightly integrated with laser scanner. With the line-scan camera RGB values of the surveyed corridor are being captured which can be assigned to the laser data
- control and data storage of all sensors
- real-time status and QC information
- pilot navigation display
In addition to the airborne system FLI-MAP comes with the following ground system components:
GPS base stations
To support high accuracy of absolute positioning of the airborne system the GPS data of the helicopter and the base stations is post-processed using kinematic GPS processing techniques
Everyday after data collection the data is collected at the field processing office for data management, QC (completeness, point density, coverage etc.) GPS and INS data is processed and data accuracy is checked.
Point density is a function of flight speed and flight altitude above ground level. To give an impression for an average flight speed of 35 kts and 100 m AGL altitude the point density will be 74 points per square meter, at 400 m AGL and same speed the point density will be 16 pts/m².
Accuracy of FLI-MAP
Due to the high accuracy of the laser scanner the relative accuracy of the LiDAR points can be quoted at 1 – 1.5 cm (1 sigma). For the absolute accuracy the GPS and INS error sources should be taken into account. Experience has shown that a 2.5 - 3 cm (1 sigma) is achievable for hard level surfaces.
Depending on the desired point density, corridor width and geometry of the corridor the number of flight passes to cover the area according to the specifications can be determined.