using 3d laser profilers and imus to measure road geometryproceedings.esri.com › library ›...

PavemetricsVision Technology for Inspection of Transportation Infrastructures

2016 ESRI – UC

LaserDigitalTerrainMapping (LDTM)

Benoit Petitclerc, P. Eng.John Laurent, P. Eng.Éric Samson

PAVEMETRICS Systems Inc.

150 Boulevard René-Lévesque Est, Suite 1820Québec, Québec, CANADAG1R 5B1

www.pavemetrics.com

PavemetricsPavemetrics LDTM – Overview

System that produces a 3D representation in the space of a scanned surface to calculate or measure:

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• Break lines and detect lane markings,

• Road edges,

• Curbs,

• Dropoff of unpaved shoulders,

• Road profile,

• Curvature,

• Slope and crossfall (super elevation)

• Etc.

PavemetricsPavemetrics LDTM components - LCMS

100km/h scanning speed

Surface geometry measurement

Full 3D model of surface

Day or night operation

High-resolution image of surface

1mm x resolutionLCMS-1 : 5mm y resolutionLCMS-2 : 1mm y resolution at 100km/h0.5 mm z resolution

Automated data processing

LCMS-1 : 11200 profiles per secondLCMS-2 : 28000 profiles per second4160 points per profile (4m FOV) 3

PavemetricsPavemetrics

Line Laser

Camera

Measurement principle

LCMS Sensor

Road/Runway/Tunnel/Rail Surface

Range

Successive Scans are Compiled to Form a Continuous Image

DZ

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PavemetricsPavemetrics Understanding 3D Imaging

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Range Intensity3D

PavemetricsPavemetricsExample of results without

compensation

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The profiles are aligned in strait line one after the other and elevation varies according to movement of the

suspension

Example: U-turn and curb jump

PavemetricsPavemetricsLDTM Components for compensation

LDTM solutions:

1 –• Optical encoder (DMI)

• Inertial Measurement Unit (IMU) x 2

2 –• Optical encoder (DMI)

• Inertial Measurement Unit (IMU) x 2

• GNSS (Rover / Base station)

Or

Commercial inertial navigation system

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Milepoint: 156.4Z, Y, Z: 46.81, -71.21, 47.12Pitch, Roll Heading: 2%, 5%, 3 DegreesLane Width: 3.5m

PavemetricsPavemetrics LDTM components

Inertial Measurement Units

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High Dynamic test

• Curbside jump

• U-turn9

Example of compensation


IMUs compensate for short wave length and GNSS for the long one wave length

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IMUs and GNSS compensation

Elevation compensated


Wandering driver test- Compensating for highly dynamic vehicle movement

Before After


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PavemetricsPavemetrics LDTM -Typical configurations

1. Stand alone mode Pure inertial using IMUs only

2. Stand alone mixed with a GNSS GNSS is necessary for absolute data position1 and to compensate the

IMU’s drift over time

3. Coupled with a commercial Inertial solution2

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1 : If no ground truth used2 : All the results in that presentation are based on that configuration

PavemetricsPavemetrics LDTM - Usage

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Evaluation of the geometry and the surface characteristics of transportation infrastructures (Road, Rail, runway, tunnel)

Machinery control on construction site

Ref.: http://www.forconstructionpros.com/article/12067870

PavemetricsPavemetrics Usage example

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Road Rehabilitation

PavemetricsPavemetrics Road Rehabilitation

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Manual Road

Surveying

GPS/Laser Controlled

Milling


Paver

Engineering CAD Tool

Ref.: http://construction.trimble.com/ Ref.: Bentley Microstation InRoads ™

PavemetricsPavemetrics Road Rehabilitation

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Milling


Paver

Engineering CAD Tool

LDTM Road Surveying (100km/h)

Ref.: http://construction.trimble.com/ Ref.: Bentley Microstation InRoads ™

PavemetricsPavemetrics LDTM – Closing the Loop

3D Road Data Collection

Data Processing

Road Condition and Geometry

PMS

Civil engineering 3D road design

and infrastructure software

New Road

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PriorityProject List

Road Maintenance

Road Design

PavemetricsPavemetrics LDTM – Closing the Loop

3D Road Data Collection

Data Processing

Road Condition and Geometry

PMS

Civil engineering 3D road design

and infrastructure software

Rehabilitated Road

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PriorityProject List

Road Maintenance

Road Design

LDTM’s DataLoop

PavemetricsPavemetrics LDTM Benefits

Build a better surface• Achieve maximum smoothness• Remove road waves and high & low spots• Ideal for projects such as highways, airports and large commercial surfaces

Reduce use of expensive material• Pave within a tighter tolerance and get closer to the minimal asphalt

thickness specification

Improve productivity• Reduce surveying costs• Faster completion

Every millimeter saved reduces milling and paving costs substantially

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As Designed• 1 mile long (5,280 feet)• 2 lanes; total width of 28

feet• 3” asphalt (76mm)• Asphalt @ $75/ton= 2,772 tons required at a cost of $207,900

As Built• 1 mile long (5,280 feet)• 2 lanes; total width of 28

feet• 3.157” asphalt (80mm)• Asphalt @ $75/ton= 2,917 tons (+145) required at a cost of $218,775

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Millimeters Matter

Just 4mm extra asphalt on 1 mile…+$10,875 in material costs

PavemetricsPavemetrics Millimeters Matter

“Concrete pavements constructed 10% less than their design thickness will reduce its life cycle by 90%”

Jim Ollis, National Survey Standard for Road and Bridge Construction in Australia and New Zealand

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PavemetricsPavemetricsLDTM vs Mobile Mapping and

Manual Survey

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1 - LDTM coupled with an Inertial system2 - Industry accepted specification values3 - Obstruction caused by objects in the field of view (ex: cars, people, trees, etc.)4- Réf.: Accuracy evaluation of a mobile mapping system with advanced statistical methods (2015)

I. Toschi , P. Rodríguez-Gonzálvez, F. Remondino, S. Minto, S. Orlandini, A. Fuller

Manual Survey LDTM1 Mobile Mapping2

Sampling rate 15 points / hour 45 Mpixels / sec. 1 Mega pixels / sec.Field of view 100 m 4 m 360 degreesPosition accuracy 3 mm 4 mm 8 to 10 mm4

Obstruction by object3 None None Yes

LDTM collects 45 Mega pixels per second over a 4m lane with the accuracy achieved by a

professional surveyor.

PavemetricsPavemetrics LDTM

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Accuracy and precision

Ref.: http://www.extremetech.com/

PavemetricsPavemetrics LDTM validation - Test Track

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Local Québec Test Site

PavemetricsPavemetrics LDTM Test Track

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Test Site Characteristics

• Allow for testing LDTM in multiple road geometry scenarios and different collection speeds- 700m straight road

- Soft curves

- Sharp turns

- Various Loops : 2.2km, 1.7km, 1.2km and dead end (200m)

- Elevation changes (approximately 2 º slope )

- More the 500 ref. points=> surveyed 3 time with total station

PavemetricsPavemetrics LDTM Test Track

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Targets used-

• Target Type- 10cm diameter disc with overlaid cross.(cont’d)

- Cross: Easy identification of the disc center for surveying


Test Site : Surveyed markers

LDTM Test Track

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Markers group

PavemetricsPavemetricsAccuracy assessment of the

ground truth

Accuracy (mm): X: 2.8 Y: 3.0 Z: 2.0 Precision (mm): X: 0.8 Y: 0.1 Z: 0.1

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0

1

2

3

4

5

6

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1 2 3 4 5 6 7 8 9 10 11

RMS Error (mm)

Markers group

“Marker Group” comparison of Survey 1 and 2

X Y Z

PavemetricsPavemetrics LDTM – Accuracy assessment

Method:

For a certain distance (300 and 825 meters)

Best fit between GT and LDTM clicked reference points

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Accuracy compare to GT (Avg. in mm): X: 5.0 Y: 4.0 Z: 2.5 Repeatability compare to first scan (mm)*: X: 3.0 Y: 5.0 Z: 2.0

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0

1

2

3

4

5

6

7

8

1 2 3 4 5 6 7 8 9 10 11 12

Average RM

S Error (mm)

Run

Multiple runs ‐ Average error compare to GT

X Y Z

Best fit « Detected Markers »vs Ground Truth –300m

*Mean of RMS Error over 11 scans


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Accuracy compare to GT(Avg. in mm): X: 9.0 Y: 7.0 Z: 5.0 Repeatability compare to first scan (mm)* : X: 6.0 Y: 6.0 Z: 4.0

0

2

4

6

8

10

12

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1 2 3 4 5 6 7 8 9 10 11 12

Average RM

S Error (mm)

Run

Multiple runs ‐ Average error compare to GT

X Y Z

Best fit « Detected Markers » vs Ground Truth – 825m

*Mean of RMS Error over 11 scans

PavemetricsPavemetrics LDTM elevation repeatability

Elevation measured between 2 reference points separated by approx. 3.5m transversally

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PavemetricsPavemetrics LDTM elevation repeatability

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0

0.02

0.04

0.06

0.08

0.1

0.12

Delta elevation per siteLDTM with commercial inertial system

Delta_LDTM Delta_GT

Average GT-LDTM (m): 0.00183Standard deviation (m): 0.001563


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1 - LDTM coupled with an Inertial system2 - Industry accepted specification values3 - Obstruction caused by objects in the field of view (ex: cars, people, trees, etc.)4- Réf.: Accuracy evaluation of a mobile mapping system with advanced statistical methods (2015)

I. Toschi , P. Rodríguez-Gonzálvez, F. Remondino, S. Minto, S. Orlandini, A. Fuller

Manual Survey LDTM1 Mobile Mapping2

Sampling rate 15 points / hour 45 Mpixels / sec. 1 Mega pixels / sec.Field of view 100 m 4 m 360 degreesPosition accuracy 3 mm 4 mm 8 to 10 mm4

Obstruction by object3 None None Yes

LDTM collects 45 Mega pixels per second over a 4m lane with the accuracy achieved by a

professional surveyor.

LDTM - Conclusion

PavemetricsPavemetrics LDTM - Conclusions

• Reduce significantly the number of reference point to be measured manually (ground truth)

• System as accurate as traditional surveying methods

• Possibility to stitch many runs to produce multi lane 3D models (highways, runways, tunnels wall, etc.)

• Fast and highly accurate solution to produce data for automatic measures of geometry and infrastructure’s surface characteristics

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