L4E_lidar

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payload I

UV sensors
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lidar scan

Scanning LIDAR

In a LIDAR system, a LASER beam is used in place of a microwave beam, to detect the distance to a target.

Scanning LIDAR is used to:

detect the distance to obstacles in front of the UAV, to help with collision avoidance
generate data for a Digital Elevation Map of the area under the UAV
detect the presence and height of trees, as shown in the plot above

See also altimeters

Scanning eye safe laser LIDAR

- from www.sickusa.com

Sick LMS 211-30206	value	units
scanning angle	100	degrees
resolution / accuracy (+/-) / range with 10% reflectivity	10 / 35 / 30	mm / mm / m
angular resolution (selectable)	0.25 / 0.5 / 1	degrees
response time	53 / 26 / 13	mS
weight	9	Kg

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Example of LIDAR scan showing tree height

Three LIDAR scans, showing trees and the ground level, from http://denali.gsfc.nasa.gov/research/laser/slicer/slicer.html

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LiteMapper LIDAR

From www.litemapper.com

The LiteMapper system is a fully integrate sensor package for highly accurate 3D measurements of the Earth's surface. It includes

High-resolution Laserscanner (scanning Lidar)
High-accuracy Position and Orientation sensor system
Control and data logging unit
Flight guidance system
Software for mission planning, system operation, data registration, geocoding, and processing
Optional Digital Video system
Optional Digital Camera system

All components are engineered for operation on airborne platforms. The compact and lightweight design and low power requirements make the LiteMapper system ideal for small survey aircraft and helicopters. A high degree of automation and tight integration with the flight guidance system make it easy to operate. A dedicated lidar operator is often not required.

Among LiteMappers special features are:

full return waveform digitization (LiteMapper 5600) for accurate and detailled mapping of vertical structures (vegetation, infrastructure), improved reliability and accuracy of elevation measurements
uniqe ability to collect true surface color information with each lidar measurement (LiteMapper 2800). Natural color and CIR true-ortho images at the lidar point density are available without additional processing.
superior range resolution and measurement accuracy

LiteMapper 5600

Versatile mid-altitude system for high-resolution topographic and corridor mapping with fixed-wing aircraft and helicopters with full waveform digitization

Specifications:

Range: up to 1500 m
Range resolution: 15 mm
Pulse repetition frequency: up to 200 kHz
Scan pattern: parallel scan lines, near-equidistant samples
Scan angle (fixed): ±22.5° (up to ±30° at reduced range)
Scan rate: variable, up to 160 scans/sec
Effective measurement rate: up to 133000 measurements/sec (@ ±30° FOV)
Full waveform digitization
" Unlimited" number of returns and intensities with each shot
Target separation down to 0.5 m within single shot
Detection of low ground vegetation down to 0.2 m height
eye-safe (laser class 1)
Sensor head dimensions: 560 x 200 x 210 mm , approx. 30 kg
typical accuracy (flat target, 850 m AGL): 0.04 m vertical, 0.12 m horizontal (RMSE, excluding GPS errors)
typical survey parameters (@ 120 kts flying speed):

Altitude above ground	Swath width	Point density / spacing
130 m (@40 kn, ±30°)	150 m	42 points per sqm / 0.15 m x 0.15 m
400 m (@±30°)	462 m	5 points per sqm / 0.46 m x 0.46 m
600 m (@±30°)	690 m	3 points per sqm / 0.57 m x 0.57 m
1000 m (@±22.5°)	1155 m	1 point per sqm / 1.04 m x 1.04 m

Waveform profile through forest area. From www.litemapper.com.

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