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1 The Geometrical Quality of Terrestrial Laser Scanner Presented by Rudolf Staiger 20.4.2005 The Geometrical Quality of TLS - R. STAIGER 2 Geometrical Quality of TLS Table of contents 1 Introduction 2 The geometrical quality of the measurements 2.1 Different methods 2.2 Specifications from the manufacturers 3 Practical Test for the Quality of Point Clouds 3.1 Resolution-Test 3.2 Noise-Test 3.3 Accuracy-Test 4 System Calibration – Overall accuracy of 10 scans 4.1 Description 4.2 Results 5 Conclusions 20.4.2005 The Geometrical Quality of TLS - R. STAIGER 3 Comparison Measurement and Modeling Tacheometer <-> Scanner Tacheometer - a few points are observed precisely - Points are representative - effort per point is high - “Think” in 3D-points - Quality -> points Scanner - a mass of arbitrary points (regular grid?) - points are non-representative - effort per point very small - “Think” in 3D-elements - Quality -> geometrical elements X 5 = 234.567 Y 5 = 56.008 Z 5 = -270.443 X 13 = 108.565 Y 13 = 176.123 Z 13 = 6.462 20.4.2005 The Geometrical Quality of TLS - R. STAIGER 4 Specifications manufacturer R: 5 mm A: 10 mm R: 3 mm @ 100 m A: 6 mm @ 50 m Position U 4 :3mm @10m R: 0,0011°(V) R: 0,00076°(Hz) 880 Iqsun A: ±2,5 mm (plane) A 2 : 5 mm A: 0,009°(V) A: 0,005°(Hz) CP 3200 Callidus R: 0,018°(V) R: 0,01°(Hz) R: 0,0025° R: 32 µrad A 1 : 60 µrad Angle L: 5 mm A: 10 /5 mm 6 U 5,6 :1,4–6,5 mm T 5,6 :3–10 mm A: +-4 mm Distance IMAGER 5003 Z & F LMS Z 420 i Riegl ILRIS-3D Optech GS 200 Mensi A: 2 mm (plane) 7 HDS 3000 Cyra Element Product Manuf. 1 Hz + V 2 typical accuracy 3 depends on averaging 4 reflectivity of 84% 5 between 5 and 100 m 6 average 7 CYRA 2500 A: Accuracy L: Linearity P: Precision R : Resolution U: Uncertainity T: Tolerance 20.4.2005 The Geometrical Quality of TLS - R. STAIGER 5 - refraction - vibrations - optical perturbations Environment Method 1 System calibration - distance - angle - Synchronization - calibration Instrument - size - orientation - curvature - surface Objects - geometry -Distance to the object - Number of scans - orientation object - with / without reference Method of Acquisition - registration with tie-points - calculation of geometrical elements Method of calculation 20.4.2005 The Geometrical Quality of TLS - R. STAIGER 6 Method 2 Single-Component-Method Calculation Acquisition Environm. Object Instrument synchronization - scale-factor - additional - cyclic distances - orthogonality - eccentricity - scale V-angles - orthogonality - eccentricity - scale Hz-angles ?? factory-calibration ?? Func tional Model

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1

The Geometrical Qualityof

Terrestrial Laser Scanner

Presented

byRudolf Staiger

20.4.2005 The Geometrical Quality of TLS - R. STAIGER2

Geometrical Quality of TLSTable of contents

1 Introduction

2 The geometrical quality of the measurements

2.1 Different methods 2.2 Specifications from the manufacturers

3 Practical Test for the Quality of Point Clouds

3.1 Resolution-Test 3.2 Noise-Test 3.3 Accuracy-Test

4 System Calibration – Overall accuracy of 10 scans 4.1 Description 4.2 Results

5 Conclusions

20.4.2005 The Geometrical Quality of TLS - R. STAIGER3

Comparison Measurement and Modeling Tacheometer <-> Scanner

Tacheometer

- a few points are observed precisely

- Points are representative

- effort per point is high

- “Think” in 3D-points

- Quality -> points

Scanner

- a mass of arbitrary points(regular grid?)

- points are non-representative

- effort per point very small

- “Think” in 3D-elements

- Quality -> geometrical elements

X5 = 234.567Y5 = 56.008Z5 = -270.443

X13 = 108.565

Y13 = 176.123Z13 = 6.462

20.4.2005 The Geometrical Quality of TLS - R. STAIGER4

Specifications manufacturer

R: 5 mm

A: 10 mm

R: 3 mm@ 100 m

A: 6 mm@ 50 m

Position

U 4 :3mm @10mR: 0,0011°(V) R: 0,00076°(Hz)

880Iqsun

A: ±2,5 mm (plane)

A2: 5 mm A: 0,009°(V) A: 0,005°(Hz)

CP 3200Callidus

R: 0,018°(V)R: 0,01°(Hz)

R: 0,0025°

R: 32 µrad

A1: 60 µrad

Angle

L: 5 mm

A: 10 /5 mm6

U 5,6 :1,4–6,5 mmT 5,6 :3–10 mm

A: +-4 mm

Distance

IMAGER 5003

Z & F

LMS Z 420 i

Riegl

ILRIS-3DOptech

GS 200Mensi

A: 2 mm (plane) 7

HDS 3000Cyra

ElementProductManuf.

1Hz + V 2typical accuracy 3depends on averaging4reflectivity of 84% 5between 5 and 100 m 6average 7CYRA 2500

A: Accuracy L: LinearityP: Precision R : ResolutionU: Uncertainity T: Tolerance

20.4.2005 The Geometrical Quality of TLS - R. STAIGER5

- refraction- vibrations- optical perturbations

Environment

Method 1 System calibration

- distance- angle- Synchronization- calibration

Instrument

- size- orientation- curvature- surface

Objects

- geometry-Distance to the object- Number of scans- orientation object- with / without reference

Method of Acquisition

- registration with tie-points- calculation of geometrical elements

Method of calculation

20.4.2005 The Geometrical Quality of TLS - R. STAIGER6

Method 2 Single-Component-Method

CalculationAcquisitionEnvironm.

ObjectInstrument

synchronization

- scale-factor- additional- cyclic

distances

- orthogonality- eccentricity- scale

V-angles

- orthogonality- eccentricity- scale

Hz-angles

?? factory-calibration ??

Functional Model

2

20.4.2005 The Geometrical Quality of TLS - R. STAIGER7

Standard case – 1 diffuse Reflection at the object

Total-Reflection combined with diffuse Reflection

?

Total-Reflection

Optical Perturbations 1

„Black holes“

Virtual Points

20.4.2005 The Geometrical Quality of TLS - R. STAIGER8

Optical Perturbations 2 Tail of a Comet

spher e

w a l l

Im age r 5003

Entire L aser beam

R ight pa rtP 1

P 2P

Left par t

20.4.2005 The Geometrical Quality of TLS - R. STAIGER9

Beispiele

Cyra 2500

(Leica)

Imager 5003 (Zoller & Fröhlich)

20.4.2005 The Geometrical Quality of TLS - R. STAIGER10

Geometrical Quality?

The geometrical quality of the raw-data (xyz-coordinate)

is of fundamental importance….

TLS is a new method

Specifications of the manufacturers ?

no redundancy no control on a point level

huge amount of data

20.4.2005 The Geometrical Quality of TLS - R. STAIGER11

Calibration of the entire system 2 Point clouds

10 scans with IMAGER 5003 (Z+F) registered pair wise by local transformations

Point identification with the standard chess-board-traget

Additional tacheometry (Leica TPS 1200) ~ 50 points in the regions L, M and R

20.4.2005 The Geometrical Quality of TLS - R. STAIGER12

Calibration of the entire system 1 description

17 5 18 2 18 3 18 4 18 5 19 1 19 2 19 3

12 4 13 3 138

12 5 12 7 13 0 1 32 14 7 10 1 10 3 10 6 1 09 119

10 0 10 2

10 4

10 5

10 7 13 1 13 4 13 6 13 7 139 18 1 18 6

18 7

18 8

18 9

19 5

19 6 19 8

21 0

X

Y

~ 90 m

~ 15 m

1

2 3 4 5 6 7

8 9

10 4

1 S canner-Posi tions Tacheomet er-P ositions Kn own- Positions

Combined adjustment

observations - local coordinates of Tie-points

- Reference coordinates from tacheometer

Unknowns - Rotation parameters R21, R32, …R910

- coordinates for all Tie-points in the tacheometric system

3

20.4.2005 The Geometrical Quality of TLS - R. STAIGER13

Calibration of the entire system 3-1 Results LRfree

Reference L+R scale free

-25

-20

-15

-10

-5

0

5

10

15

20

25

90 100 110 120 130 140 150 160 170

coordinate X [m]

dev

iatio

ns

[mm

]

DX

DY

DZ

Reference points in the regions L and R, scale unknown

Deviations: DX = XTachy –XScanner, DY = YTachy –YScanner, Dz = …..

20.4.2005 The Geometrical Quality of TLS - R. STAIGER14

Calibration of the entire system 3-2 Results LRfixed

Reference points in the regions L and R, scale is fixed to 1.00000

Reference L+R scale fixed

-20

-15

-10

-5

0

5

10

15

20

25

90 100 110 120 130 140 150 160 170

coordinate X [m]

dev

iatio

ns

[mm

]

DX

DY

DZ

20.4.2005 The Geometrical Quality of TLS - R. STAIGER15

Calibration of the entire system 3-3 Results Lfree

Reference points in the region L scale is unknown

Reference L - scale free

-50

0

50

100

150

200

90 100 110 120 130 140 150 160 170coordinate X [m]

devi

atio

ns [

mm

]

DX

DY

DZ

20.4.2005 The Geometrical Quality of TLS - R. STAIGER16

Calibration of the entire system 3-4 Results Lfixed

Reference points in the region L scale is fixed to 1.00000

Reference L - scale fixed

-60

-40

-20

0

20

40

60

80

100

90 100 110 120 130 140 150 160 170

coordinate X [m]

devi

atio

ns [

mm

]

DX

DY

DZ

20.4.2005 The Geometrical Quality of TLS - R. STAIGER17

Conclusions

System check accuracyExample: IMAGER 5003 (ZF), 10 scans , Area of 15 X 90 m

good to ideal conditions L+R 10 - 20 mm scale no influenceunfavorable conditions L or R only 100 - 200 mm scale strong influence

System specifications manufacturer…..

not reproducible and not not standardized

Requirement for standardized specifications which can be reproducedideal case related to geometrical elements

Geometrical Quality of the scans …..check on different levels- measurement noise Theory and practice- component methods distance or angle part- system calibration method (incl. Registration, Point identification, Geo-

referencing, etc…)