How does laser scanning work? Explore the ins and outs of laser scanning or LiDAR as it is commonly known. If you would like to find out more - please drop us a line at info@3dlasermapping.com or have a look at our website www.3dlasermapping.com

1. AN INTRODUCTION TO LASER SCANNING
PART 1

2. LIDAR
• YOU WILL OFTEN HEAR THE TERM ‘LIDAR’
• LIGHT DETECTION AND RANGING
• OR A COMBINATION OF THE WORDS LIGHT AND RADAR
• TECHNOLOGY TO MEASURE DISTANCES BY ILLUMINATING A TARGET WITH A LASER AND
ANALYSING THE REFLECTED LIGHT TO DETERMINE DISTANCE
• NUMEROUS PLATFORMS, APPLICATIONS AND TECHNIQUES

3. ?!

4. TYPES OF LASER SCANNER
• THERE ARE MANY DIFFERENT TYPES OF LASER SCANNER
• THE MOST COMMON TYPES FOR SURVEYING ARE:
• TIME OF FLIGHT (PULSE-BASED)
• PHASE SHIFT
• LATEST SCANNERS CAN MEASURE UP TO 1 MILLION POINTS PER SECOND

5. TIME OF FLIGHT SCANNERS
• PULSE OF LIGHT EMITTED BY LASER SOURCE
• LIGHT IS REFLECTED OFF AN OBJECT BACK TO LASER SENSOR
• SPEED OF LIGHT IS KNOWN SO WE CAN CALCULATE DISTANCE
time

6. PHASE SHIFT SCANNERS
• SIMILAR CONCEPT TO TIME OF FLIGHT SCANNERS
• CONSTANT BEAM OF LASER ENERGY IS EMITTED
• SCANNER MEASURES THE PHASE SHIFT OF THE RETURN LASER ENERGY TO
CALCULATE DISTANCE

7. WHICH SCANNER?
Scanner Type Pros Cons
Time of Flight Good range
(1m – 6km), multiple
target capability
Expensive
Phase Shift Cheap, slightly more
precise
Low maximum range
(<500m), can have
ambiguous measurements

8. WAVEFORM DATA - MULTIPLE TARGETS

9. WAVEFORM DATA - MULTIPLE TARGETS

10. WAVEFORM DATA - MULTIPLE TARGETS
Rock face with fine mesh- Jwaneng Diamond Mine, Botswana

11. WAVEFORM DATA - MULTIPLE TARGETS

12. WAVEFORM DATA – DIGITIZING AND ANALYSIS
• THE ENTIRE WAVEFORM IS CAPTURED AND DIGITIZED
• EXTRACTED ECHOES AT A CERTAIN TIME PROVIDE RANGE
• ADDITIONAL INFORMATION ABOUT THE SHAPE OF THE PEAK INDICATES QUALITY

13. WAVEFORM DATA – DIGITIZING AND ANALYSIS
• MULTIPLE ATTRIBUTES CAN BE MEASURED FROM THE WAVEFORM DATA

14. LASER SCANNER INTENSITY
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15. AMPLITUDE & REFLECTIVITY
Amplitude Reflectivity

16. MEASURING IN 3D
• LASER SCANNERS USE A MOVING MIRROR TO MEASURE ON A 2D PLANE
• ROTATING POLYGON MIRROR
• OSCILLATING MIRROR
• TO MEASURE IN 3D THE SCANNER MUST EITHER:
• ROTATE
• TRIPOD BASED SCANNER
• MOVE
• PLATFORM MOVES PROVIDING A TRAJECTORY
• EXAMPLES INCLUDE HELICOPTERS, FIXED WING, CARS, UAVS ETC.

17. DO YOU WANT TO KNOW MORE?
IF SO, GO TO WWW.3DLASERMAPPING.COM FOR MORE
INFO, OR GIVE US A CALL
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