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LIDAR

Light Detection and Ranging (Remote Sensing System)

March 2012

CE 316

CHAPTER 8

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8.1 Introduction

LIDAR: Laser Detection And Ranging

Defined: LIDAR (Light or laser Detection and Ranging) is an optical remote

sensing technology that measures properties of scattered light to find range

and/or other information of a distant target (i.e. collect topographical data)

Defined: LADAR (Laser Radar) used in military context. LADAR uses laser

beams to scans and process the signal echoed from targets, to create a

.

The primary difference between LIDAR and laser

radar is that with LADAR, much wavelengths

of the electromagnetic spectrum are used, typically

in the ultraviolet, visible or near infrared.

The LADAR processor looks for in the scenes. The

processor continuously compares these patterns with 3D targets files stored

in the weapon's memory.

Laser view of Scud mobile launcher

hidden between two trucks. Speed detection?

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8.2 Background

Data Use

- Digital elevation maps (DEM)

Many names of LIDAR

- Laser Altimetry, airborne laser scanning, and airborne

laser terrain mapping

Spatial Data Collector

- Collects data from a small aircraft via laser scanner,

Global Positioning System (GPS) and

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Airborne Laser Terrain Profiler, Penny (1971)

Advances:

•

• GPS (DGPS)

• IMU

•

Ground based LiDAR

8.3 LIDAR For Terrain Mapping 8.3.1 History

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8.3 LIDAR For Terrain Mapping

8.3.2 What is Lidar and how does it work

A typical LIDAR system rapidly transmits that

reflect off the terrain and other objects.

The return pulse is converted to electrical impulses and collected by a

high-speed data recorder.

Since the formula for the speed of light is well known,

time intervals from transmission to collection are

easily derived.

.

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8.3.3 Components of LIDAR22

Typical LiDAR components (Wehr and Lohr, 1999)

8.3 LIDAR For Terrain Mapping

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A basic LIDAR system involves a laser range

finder reflected by a rotating mirror (top). The

laser is scanned around the scene being

digitized, in one or two dimensions (middle),

gathering distance measurements at specified

angle intervals (bottom).

8.3.4 Components of LiDAR22

8.3 LIDAR For Terrain Mapping

281 Pitch (http://www.nasm.si.edu/exhibitions/gal109/NEWHTF/HTF541B.HTM)

11.3 LIDAR for Terrain Mapping

11.4.3 Pitch 11.4.4 Yaw

11.4.3 Roll

8.3.5 Roll

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Season

11.4 Using LIDAR

Active Sensor - Sun independent, can conceivably be used 24/7

(Wehr and Lohr, 2005)

Limited by weather conditions (Li and Baker, 2003)

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8.4.1 Limits

Rain and fog

•

High density vegetation

• Forest cover ≥ 80% result in low density ground

points

•

Terrain Slope

• Errors increase with sloped land

8.4 Using LIDAR

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Most terrain can be mapped with LIDAR

Water

• Generally near infra-red lasers (most common)

can not be used

• Blue/green laser (penetrates up to 50m)

Sloping terrain

•

8.4.2 Terrain

8.4 Using LIDAR

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Average values from a typical LiDAR Scan

(reproduced from Elsheimy et al. 2005)

8.4.3 Average Scanning Values

8.4 Using LIDAR

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Constant velocity rotating mirror scanning technique (El-Sheimy et al., 2005)

8.4.4 Constant Velocity Rotating Mirror Scanning

8.4 Using LIDAR

287

Oscillating mirror scanning technique (El-Sheimy et al., 2005)

8.4.5 Oscillating Mirror Scanning

8.4 Using LIDAR

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8.4.6 Fibre Optic Scanning

Fibre optic scanning technique (El-Sheimy et al., 2005)

8.4 Using LIDAR

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8.4.7 Elliptical Scanning

Elliptical scanning technique (El-Sheimy et al., 2005)

8.4 Using LIDAR

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8.4.8 Coordinates

Geo-referenced data (x,y,z)

• In North America, references the NAD 83

• One ground control station is needed within

30km of the project site (NCGC Report EM 1110-

1-1000, 2002)

•

8.4 Using LIDAR

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8.4.9 Equipment Providers

Optech ALTM 3100EA http://www.optech.ca/prodaltm.htm

8.4 Using LIDAR

Falcon II equipment http://www.toposys.com/

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8.4.10 LIDAR Vendors

LiDAR Worldwide vendors (NCGC Report EM 1110-1-1000, 2002)

• 1995 (3)

• 2000 (50)

8.4 Using LIDAR

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8.4.11 Major Canadian Consultant

LiDAR Services International Inc., Calgary, AB.

• Projects:

Highway corridor survey (Sask. Highways)

4 new Uranium Mine Sites, Northern Sask.

Many in Alberta, Manitoba, US, etc.

Multiple projects on 5 continents

8.4 Using LIDAR

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Offices: Houston, Calgary and Ottawa

Projects:

• Oil and Gas

• Land Development

• Power-line and Pipeline

• Transportation

• Mining

• Flood Plain

8.4.11 Major Canadian Consultant

8.4 Using LIDAR

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8.4.12 How much?

Cost versus vertical accuracy (Li and Baker, 2003)

8.4 Using LIDAR

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(NOAA Coastal Services Centre, 2006)

http://www.csc.noaa.gov/crs/rs_apps/sensors/lidar.htm#cost

NOAA Coastal Services Center

• $1000 to $2000 US per Mi2

• Includes:

Flight

Data collection

Post-processing

Delivery

• Dependant on location and specifications

8.4.12 How much? 8.4 Using LIDAR

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Coastline protection

Floods

City Models

Nature Conservation

Open pit and deposits

Corridor mapping

Research

8.4.13 Applications

8.4 Using LIDAR

These data are collected with aircraft-mounted

lasers capable of recording elevation

measurements at a rate of 2,000 to 5,000 pulses per

second and have a vertical precision of 15

centimeters (6 inches). After a baseline data set has

been created, follow-up flights can be used to

detect shoreline changes.

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8.4.13 Applications

• Manitou Beach Road

Section 1 Scan 2

LiDaR 3D Screen Shot

8.4 Using LIDAR

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8.4.13 Applications

8.4 Using LIDAR

• Manitou Beach Road Scan Near Danceland

LiDaR 3D Screen Shot

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8.4.14 Products

Digital Surface Model (DSM)

(Earth’s surface including objects)

8.4 Using LIDAR

Digital Terrain Model (DTM)

(Earth’s Surface only)

Döbern redevelopment area © eta AG, Germany

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Digital Terrain Model (DTM)

8.4.14 Products

8.4 Using LIDAR

Relief image of Celtic chieftain’s settlement

Heuneburg

3D presentation of Roman fortified

camp Cava de Viriato near Viseu, Portugal

http://www.toposys.com/joomla/index.php?option=com_content&view=article&id=63&Itemid=92&lang=en

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Point cloud model

Point cloud with errors removed

(www.toposys.com, 2006)

8.4.14 Products

8.4 Using LIDAR

REF: http://www.toposys.com/joomla/

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8.4.15 Cases

Gutelius (1998)

• Successful applications in highway engineering, coastal

mapping and corridor mapping for power lines (500-

600km per day)

Berber and Shortridge (2005) and Webster and Dias (2005)

•

8.4 Using LIDAR

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Terminology

• Create an industry and academic

standard

8.5 Discussion

Industry versus Academia

• Is the data up to the required standards

Appropriate applications

• LiDAR is the most accurate remote

sensing technology, use it appropriately

and when necessary

REF:

http://www.toposys.com/joomla/