Applications Part 2

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Coordinamento SIBACoordinamento SIBAUniversità degli Studi di LecceUniversità degli Studi di Lecce

ApplicationsPart 2

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Active 3D sensing:Applications

Prof. Virginia Valzano(Director of SIBA Coordination)

ICHIM01 Tutorial ProgramICHIM01 Tutorial ProgramSeptember 3-4, 2001September 3-4, 2001Museum & Heritage Applications of Museum & Heritage Applications of Digital 3D Imaging Digital 3D Imaging Track 5: Multimedia for the WebTrack 5: Multimedia for the WebSeptember 3 Afternoon September 3 Afternoon

presented by Dr. Adriana Bandiera (SIBA Coordination)

Eng. J-Angelo Beraldin (National Research Council of Canada, Project partner)

Latest ResultsLatest Results

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• SIBA Coordination is the structure of the University of Lecce that co-ordinates, manages and develops the Telematic Information System for Research and Education.

• It coordinates the development of the University libraries computerization.

• It coordinates relations with other national and international Universities and Research Centres for the achievement of information systems and other shared projects.

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• SIBA Coordination offers to scholars and students the possibility to access to a coordinated system of bibliographical and documentation resources in digital format and full-text.

• SIBA Coordination is involved in the coordination and development of numerous activities and national and international projects for the retrieval and the assessment through electronic media of archaeological finds, books, and documentary material of high historical value and archival rarity.

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• It is engaged in the development of coordinated services aimed at:– digital reproduction– digital preservation – virtual restoration – assessment of the historical, scientific and cultural

holdings of the University.

• It is also engaged in the development of methodologies for the use of digital technologies within the cultural heritage field by means of the use of innovative technological and computerized systems.

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SIBA Laboratories

• Server Laboratory: http://siba2.unile.it/sedi/lab_serv.html• Laboratory for the acquisition and processing of

bibliographical and documentary information http://siba2.unile.it/sedi/labelbib.html

• Laboratory for the digital acquisition and processing of images http://siba2.unile.it/sedi/labdig1.html

• GIS Lab (Geographic Information Systems) http://siba2.unile.it/sedi/labgis.html

• 3D Lab (acquisition and processing of three-dimensional images) http://siba2.unile.it/sedi/lab3d.html

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Staff for the 3D projects at the Staff for the 3D projects at the SIBA labSIBA lab

General Coordinator: Virginia Valzano

Antonio Marra

Adriana Bandiera

Fabrizio Bergamo

Maria Carmela Catamo

Rosita Ingrosso

Flavio Melcarne

Collaborators:

Technical Responsible:

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http://siba3.unile.it/ctle/http://siba3.unile.it/ctle/

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Coordinated project of Catania and Lecce Universities

• The project foresees the digital acquisition and processing of bibliographic and documentary information

• Digital reproduction of archaeological objects and finds of particular importance

• Acquisition and processing of images and three-dimensional models and environments, for restoration and virtual reconstruction.

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The Laboratory for the digital Laboratory for the digital

acquisition and processing of acquisition and processing of

images images of the SIBA Coordination, is one of the most advanced in Italy. It possesses sophisticated HW and SW equipment, which allows the acquisition of digital images at both low and high resolutions.

(http://siba2.unile.it/sedi/labim.html)

Laboratory for the digital acquisition and processing of 2D images

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The balancing platformbalancing platform

and the HMI cold light HMI cold light

lampslamps allow the

acquisition of images in

compliance with the

regulations for the

preservation of the

documents.

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•The digital Back Dicomed allows the acquisition of colours and information invisible to the naked eye •7520x6000 pixel (129 Mb)

•The digital Back Mamiya 645 allows the acquisition at a maximum resolution of 3000x2000 pixel

•The workstation allows the processing of digital images for virtual restoration

Digital scan back(max res. 7520 x 6000 pixels)

Instantaneous digital back(max res. 3000 x 2000 pixels)

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Frontispiece of an old printed bookFrontispiece of an old printed book

DetailDetail

Archives of old printed books images:

High resolution images: ~ 2000 x 3000 pixel

Low resolution images: ~ 550 x 850 pixel

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Demotic and Greek papyri archive:Original and virtual restoration

Fragment of Greek papyrus of Ptolemaic era (III/II BC) containing a list of names. 3,8 cm x 8,8 cm

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Detail of a high resolution image - Detail of a high resolution image - originaloriginal

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Virtual restorationVirtual restoration

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Pectoral of mummy retrieved from CartonnagePectoral of mummy retrieved from Cartonnage30 cm x 23 cm 30 cm x 23 cm

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Virtual restoration

• The virtual restoration is not in contrast with the "traditional" restoration performed on the physical document. The virtual restoration represents a tool of cognitive integration, to obtain that information that went lost or that is unlikely deducible from the original copy.

• It allows the optimization of the legibility of the textual and artistic informative data, without turning to interventions often traumatic for the original copy.

• Besides, the virtual restoration is always reversible unlike the traditional one

• It allows an in-depth study on possible interventions of traditional restoration.

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Digital acquisition, processing, virtual restoration and three-dimensional reconstruction of archaeological finds, architectural structures and objects of high historical and artistic value, as well as the preservation, enhanced knowledge and increased accessibility.

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Scuola di Specializzazione in Archeologia, Università degli Studi di Lecce

Centro di Ricerche Informatiche per i Beni Culturali, Scuola Normale Superiore di Pisa

Dipartimento di disegno industriale e tecnologia dell'architettura, Politecnico di Milano

Institute for Information Technology, National Research Council, Canada

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Mensi SOISIC 2000 3D laser scanner(short range version)

SIBA Coordination – 3D Laboratory

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Mensi SOISIC 2000 Triangulation-based 3D laser scanner

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Scanner 3D laser Mensi SOISIC 2000 – technical specifications

distance range: 0.8-10 m

scanning speed: 100 pt/sec

laser wavelength: 640 nm

Field of view (FOV): 46°

Panoramic FOV: 320°

size: 1 x 0.2 x 0.4 m

minimal mesh: 0.2 mm per meter

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Supplied by scannermanufacturer

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2.00

2.00

2.00

2.00

2.01

2.60

0.68

3.43

4.75

5.00

6.11

MENSI CD

Best XY Resolution = 0.2 mRad2/10 mm per 1m

@ 2.00 m 5 000 voxels/line@ 3.43 m 4 000 voxels/line

z = 0.3 mm

z = 0.8 mm

5 000 voxels,x=0.4 mm



z = 0.6 mm

z = 1 mm

Best z (mm) = 0.143 z (m)1.07

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0.60 0.80 2.40

Beam divergence0.2 mrad

Adapted by user

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Vivid 900

near field mm (@ 0.6 m)

far field mm Depth accuracy (mm)

Tele Lens:

111 x 84 x 40

460 x 350 x 130 (@ 2.5 m)

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Mid Lens:

196 x 153 x 70

830 x 622 x 220 (@ 2.5 m)

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Wide Lens:

355 x 266 x 92

1200 x 903 x 400 (@ 2 m)

0.64

scanning speed: 100 000 pt/sec

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DELL Workstation for processing and modelling in 3D

Dual 1 GHz Intel Pentium III CPUs

1 Gbyte of RAM

Video adapter Intense 3D 4110 WildCat

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Mensi 3D Ipsos

Okino Polytrans

Innovmetric Polyworks

Rhino Geomagic Studio

Autodesk Autocad 2000i

Alias/WaveFront Studio

Softwares for processing and modelling in 3D

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3D A3D ARCHAEORCHAEO 3D B3D BYZANTINEYZANTINE

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Digital acquisition and construction of three-

dimensional models of archaeological finds,

environments and sites of the Salento Peninsula.

Therefore the creation of several databases, as for

instance the 3D stelae and cippus database and

others, concerning in particular the archaeological

excavations of Cavallino (LE), is expected.

3D A3D ARCHAEORCHAEO

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http://siba2.unile.it/scuola_archeo/http://siba2.unile.it/scuola_archeo/

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3D A3D ARCHAEORCHAEOArchaeological excavations of Cavallino (LE)Archaeological excavations of Cavallino (LE)

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Stelae of the VIIIth and VIIth sec. b.c. and

the cippus of the of the III sec. b.c.,

discovered in the Salento territory during

some excavation sessions organized by

the Archaeological Superitendence of

Puglia and by University of Lecce.

3D A3D ARCHAEORCHAEO3D Stelae and Cippus3D Stelae and Cippus

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3D A3D ARCHAEORCHAEO3D Stelae and 3D Stelae and

CippusCippus

Example of stelae

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3D A3D ARCHAEORCHAEO3D Stelae & Cippus3D Stelae & Cippus

CippusCippus of Otranto (LE) with messapian inscriptions (III of Otranto (LE) with messapian inscriptions (III sec. b.C.)sec. b.C.)

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This example has been

discovered in the territory of

Cavallino (LE) in a heap of stones

dumped by farmers near to a

“dolina” at the centre of a fenced

zone of archaic fortifications. As

described by the Director of the

school of archaeology of the

University of Lecce, it is a

fragment of a stele

(33x39x12cm) rather badly

preserved, very splintered and

with large calcareous crusts even

on the figured area.


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On the front side we

see a very low and

flat relief whereon we

can recognize two

horses attached to a

two-wheel vehicle

and a human shape,

in a primitive

representation, where

all elements are

taken to pieces and

spread over a single

plane.


3D Stelae and Cippus3D Stelae and Cippus

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This example has been discovered in the

ancient Messapian settlement of “Muro

Tenente” in the province of Brindisi. It is a

stele on which we can see a war chariot

and two rows of hoplites with helmets

and long lances.

As specified by Prof. D’Andria, we can

find in this stele, as in the one of

Cavallino, a reticulated rectangular motif

at the lateral side, and, at the front side,

we see a representation in which all

elements are taken into pieces and

spread over a single plane.



107x51x14 cm

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Stele Z uncertaintySpatial XY Resolution

N. 1 (Cavallino) 0.6 mm 0.3 mm

N. 2 (Muro Tenente)

1 mm 0.3 mm

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For both examples two 3D models have been produced, one with and the other without texture.

To this purpose some digital photos have been used, produced with the digital camera Kodak Dc 265 of the Laboratory for the Digital Image Acquisition and Processing of the SIBA Coordination.



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These photos, imported in Adobe Photoshop, have been calibrated, combined, resized and adapted to the model and afterwards they have been projected on it by means of Alias/Wavefront Studio.

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http://siba3.unile.it/ctle/3ddb/3dstele.html

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5 hours to perform all the 3D scans

3D Scan with Soisic: standoff = 2 m

A total of 2D & 3D images were acquired and used for the complete model

Spatial resolution = 1st model 1 mm; 2nd model scan 0.3 mm

Total of about 1.200.000 points

After filtering and meshing total of about 1.200.000 polygons (triangles)



Stele n. 1 Stele n. 1 Muro Tenente (BR)Muro Tenente (BR)

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Cloud of pointobtained with

3D scanner


CippusCippus

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Coordinamento SIBACoordinamento SIBAUniversità degli Studi di LecceUniversità degli Studi di Lecce 3D A3D ARCHAEORCHAEO

3D Stelae and 3D Stelae and CippusCippus

Shaded Shaded 3D Model3D Model

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CippusCippus


3D scanner

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Coordinamento SIBACoordinamento SIBAUniversità degli Studi di LecceUniversità degli Studi di Lecce 3D A3D ARCHAEORCHAEO

3D Stelae & 3D Stelae & CippusCippus

Shaded Shaded 3D Model3D Model

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3D Models with texture map3D Models with texture mapFrom 2D images after rectificationFrom 2D images after rectification


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Stele n. 2 Stele n. 2 Cavallino (LE)Cavallino (LE)

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6 hours to perform all the 3D scans

3D Scan Soisic: standoff = 1.80 m

A total of three 3D images were scanned and used for the complete model

Spatial resolution: 1st and 2nd scan 0.6 mm; 3rd scan 0.3 mm

Total of about 300.000 points

After filtering and meshing total of about 272.000 polygons (triangles)


Work performed January 3-4, 2001

Stele n. 2 Stele n. 2 Cavallino (LE)Cavallino (LE)

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3D A3D ARCHAEORCHAEO3D Stelae & 3D Stelae &

CippusCippus


3D scanner

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3D A3D ARCHAEORCHAEO3D Stelae & 3D Stelae &

CippusCippus

ShadedShaded3D Model3D Model

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3D Models3D Models


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Digital acquisition and construction of three-

dimensional models of structures and

environments of subterranean and sub divo

Byzantine churches of the Salento Peninsula.

3D B3D BYZANTINEYZANTINE

3D Crypts3D Crypts 3D Sub Divo3D Sub Divo

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Crypts in the Salento PeninsulaCrypts in the Salento Peninsula

Nardò (LE)

Supersano (LE)

Veglie (LE)

3D B3D BYZANTINEYZANTINE

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3D B3D BYZANTINEYZANTINEFirst test site: 3D CryptsFirst test site: 3D Crypts

Santa Cristina Crypt, Carpignano (LE)

• This project is unique in Italy

• There are only a few models of this complexity that have been published worldwide

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Santa Cristina Crypt, Carpignano (LE): Outside view

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From Preparation to Actual Models: Part 1

• Estimating time to acquire the range images, build the 3D models and determine required quality of model: – Using information about the site (books, personal visits,

drawings, photographs, stereo pairs, video, indoor/outdoor etc.).

– Getting a rough estimate of size. – Establishing a mapping strategy. – Trying to predict shadows, occlusions, camera

saturation, etc…– Determining standoff distance, uncertainty, resolution!

• Z 2.5 m, z 0.4 mm, xy 5 mm

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From Preparation to Actual Models: Part 2

• Preparing and verifying equipment in the laboratory: no surprises on site.

• Installing equipment on the site and perform system self-diagnostics, verifying accuracy.

• Performing actual 3D survey. • Monitoring the changing environmental conditions

and system performance.• Creating coarse model on-line and verifying missing

data in order to re-survey those areas of the object and/or environment.

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Starting point: a hand made drawing

by Prof. Emilio Bandiera, University of Lecce(Published in: E. Bandiera, Carpignano Salentino. Centro, frazione, casali, Cavallino 1980)

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Some photographs

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Time allocation using a fast scanner (20X)

Time allocation

12%

10%

8%

0%

10%

60%

Acquisition time Warm-up time Back-ups

Commu. Troubles Set-up every day Next best-view

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Actual time with current scanner

Total of 92 hours in the Crypt

• 50-3D images for the Crypt

• 30-3D images for the altar

Time allocation

50%

9%

2%

4%

4%

31%

Acquisition time Warm-up time Back-ups

Commu. Troubles Set-up every day Next best-view

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Comments

• Decreasing the scan time does not lower (by a significant amount) the time it takes to create a 3D model!

• Scanner for distances between 2 m and 6 m are not readily available!– This range represents the transition

between triangulation and time of flight technologies

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Alignment method with spheres

3 images aligned with a common sphere

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Prediction of uncertainty in aligning 2 views

• Monte Carlo simulation • Assume errors on

measurement of sphere centres are distributed according a Gaussian distribution

• Average distance between spheres is between 700 & 800 mm

• How can one predict the errors?

Starting point: s

pheres 1,2,3

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Results of simulation in 2D space

Case 1: 0.1 mm

Case 2: 0.6 mm

mm mm

mm90o

n

n : normalwithout noise

n’

n’ : normal afterIntroduction of noise

Angular uncertainty

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Simulation results in 2D spaceDistance between 2 centres (L)=700 mm

Results of Monte Carlo simulation

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.2 0.4 0.6 0.8 1 1.2

Noise level (mm)

An

gu

lar

un

cert

ain

ty

1 si

gm

a (d

eg)

Angular uncertainty 0.068o 1.2 mrad @ 2.5 m => 3 mm

2500 mm

3 mm

zL

The larger the triangle base (L), the better!The larger the triangle base (L), the better!

Case 2: 0.6 mm

{

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Alignment of a set of images with spheres

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Verification of accuracy on-site: stadia (staff of known length)

Stadia’s length: 699.3 mm ?Temperature coefficient = ?

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Verification of accuracy on-site: stadia – deviation from standard

Stadia’s length: 699.3 mm ?

After measurements in 3D images12 positions (2 per day)Average = 700.8 mm= 0.85 mm= + 1.5 mm (+ 0.2%)There is either a scale in data, stadia has a different length or fitting routines problems!

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Results of alignment procedure: sphere diameter (derived from alignment)

Given diameter 76.0 mm ?Average = 76.2 mm = 0.6 mm

Automatic Registration of world2 on world1

Diameter of new spheres in world1

SSPHERE0004 : 75.592281mm

SSPHERE0005 : 76.140262mm

SSPHERE0006 : 76.583424mm

SSPHERE0007 : 76.565477mm

SSPHERE0008 : 76.234226mm

SSPHERE0009 : 76.147698mm

.

.

.

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Results of alignment procedure: deviation image to image (local error)

N=120Goal is 0 mmAverage = 0.87 mm = 0.88 mm Sample:

Distance between two spheres

---------------------

SSPHERE0004 <--> 2/SSPHERE0004 : 0.47718565mm



Average distance: 0.32758712mm

}= + 0.87 mm

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Results of global alignment: final deviation 1st image to last image

• Distance between two spheres: Average distance: 11.358506 mm• SSPHERE0001 <--> 2/SSPHERE0001 : 16.873245mm• SSPHERE0002 <--> 2/SSPHERE0002 : 16.369911mm• SSPHERE0003 <--> 2/SSPHERE0003 : 18.154042mm• SSPHERE0075_1 <--> 2/SSPHERE0075_1 : 6.3916981mm• SSPHERE0076_1 <--> 2/SSPHERE0076_1 : 4.9938125mm• SSPHERE0077_1 <--> 2/SSPHERE0077_1 : 3.0152716mm• SSPHERE0064 <--> 2/SSPHERE0064 : 19.74005mm• SSPHERE0065 <--> 2/SSPHERE0065 : 21.37472mm• SSPHERE0075 <--> 2/SSPHERE0075 : 6.5058957mm• SSPHERE0076 <--> 2/SSPHERE0076 : 5.2144308mm• SSPHERE0077 <--> 2/SSPHERE0077 : 3.082487mm• SSPHERE0031 <--> 2/SSPHERE0031 : 16.006866mm• SSPHERE0032 <--> 2/SSPHERE0032 : 7.9277816mm• SSPHERE0033 <--> 2/SSPHERE0033 : 13.368878mm

}} Stating pointStating point

}} Central pointCentral point

}} End pointEnd point

}} Away from start Away from start

}} Extra end point Extra end point

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Section of Crypt

wire meshOrthographic projection(units mm)

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Section of Crypt: from a CAD8

m

16.5 m

64

65

Some of the spheres

1 2

3

33 31

32

75 76

77

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3D model of Crypt:resolution of 10 mm, 1 colour per 3D image

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3D model of Crypt:resolution of 10 mm, Shaded

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Lower section: wire mesh

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Back wall: shaded

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Intangibles

Cat Vibrations caused by

constructionFlies

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Protect your investment: hire a guard!

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Conclusion• Model building using spheres vs actual 3D

data used in a global alignment procedure– Closure of the model is about 11 mm (1:1500) – Could be improved by using the 3D data for the

alignment (e.g. Polyworks Modeler)

• Time to acquire a 3D model– Predictable with good certainty– Does not change a lot even with a faster scanner

• Texture– Important and will be looked at in a later phase of

the project, – along with the 5-mm resolution 3D model

Documents

Applications Part 2