FUNDAMENTAL CONCEPT OF LIGHT DETECTION AND RANGING

1. LiDER
SYED SAMIUL HAQUE
KAZI NAZRUL UNIVERSITY
DEPERMENT OF GEO-INFORMATICS

2. LiDER
Light detection and Ranging is Active Remote Sensing Methods that uses laser to measure
variable distances to the Earth.
LiDER uses Ultraviolet,visible,infrared sense the objects and can penetrate low density of the
objects including trees.
Light energy emitted by the LiDER system is know the Pulse light, and reflect from the object
is know the Return.
 LiDER system sends a pulse and it wait pulse to return.
This travel time the light of pulses can be used to create
3d representation of the surface.

3. COMPONENTS of LiDER
Laser Scanner
• Scan the ground from side to side as the plane flying. The sensor is commonly green or NIR band.
• Frequency 50000 to 20000 pulses per second(HZ).
• Scanning angle 75 degree (Receives reflected pulse from surface return).
High Precision Clock
• Records the time to laser pulse leaves and return to scanner.
GPS
• Tracks the Altitude and Location of Airplane( x, y, z location of scanner) and accurate terrain elevation value.
IMU(inertial measurement unit)
• Measure of the angular orientation of the scanner relative to the ground and gives the precise orientation of the
scanner.
Computers
• Data storage and management
system.

4. PRINCIPLES OF LiDER REMOTE SENSING
The working principal of light Detection and ranging is quite simple.
A LiDER sensor mounted on the aircraft or helicopter.
It generally laser pulse which sent to surface /target measure the time and it takes to return to his source.
The different time ,with the angle the pulse of light was fired, and the location of the system itself and will able to
give the 3D coordinate target of the object.
The actual calculating for measuring how far a retiring a light photon has travel to and from and object is
calculated
 using following equation: Distance=(Travel Time)*(speed of light )/2

5. LIDER SYSTEM (PLATFORMS)
AERIAL/AVIATION(Airborne based LIDER): For highly detailed local elevation data. Small area where highly
density is needed.
SATELLITE(Space borne based LIDER): Cover Large areas with less details.
TERRESTRIAL(Ground based LIDER): Where the system will be fixed to the ground.

6. ADVANTAGES
All data geo-referenced from inception.
High level of accuracy.
Ability of cover large area quickly.
Quicker turn around less labour intensive and lower.
Cost than photogrammetric methods.
Can collect data steep terrain and shadows.
Can produce DTM and DSM.
DISADVANTAGE
Inability of penetrate very dense canopy leads to elevation model error.
Very large data set that are difficult interpreted and process.
No international protocols.
Highly cost.

7. LiDER DATA FORMAT
LiDER data generate from point cloud.
Point values are usually delivered by vendors as either ASCII point files or LAS format.
LIDER PROCESSING SOFTWARE
Micro station
Terra scan.
Arc GIS(work station,lider analyst,3d analyst ,lP360).
Lica photogrammetric suite..

8. APPLICATION
Mapping for corridors (roads,railway tracks,pipelines,waterway,landscape).
Mapping for electrical transmission lines.
DSM and DTM generation,espically in forest areas.
Study of drainage pattern.
Measurement of costal areas ,including dunes ,determination of costal change and erosion.
High accuracy and very dense measurement application-flood maping,DTM generation,volume calculation,
waste deposit.
3D mapping and model for important infrastructure and architectural design.
3D city model.
Rapid mapping and drainage assessment after natural disaster after landslides earthquake cyclone.
Measurement of snow and ice cover areas including glacier monitoring or wetlands.
Derivation of vegetation parameters -Tree height tree density biomass estimation determination of forest borders.
Orthoimage and true orthoimage generation.
Hydrographic survey in depths up to 50-70m.
Plant growth monitoring in precision farming.

9. THANK YOU