Multi-Resolution Digital 3D Imaging & Modelling applied to the Documentation of rock art sites: Grotta dei Cervi in Italy

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1 Multi-Resolution Digital 3D Imaging & Modelling applied to the Documentation of rock art sites: Grotta dei Cervi in Italy J.-A. Beraldin 1, V. Valzano 2, A. Bandiera 2 1 IIT, National Research Council Canada, Ottawa, Ont, Canada, K1A OR6 2 SIBA, University of Salento, LE, Italy, 73100

2 High-Res 3D imaging for rock art sites Textured 3D, Why? Record, What? It: Grotta dei Cervi: Eng: Stag Grotto Fr: Grotte des Cerfs 3D documentation of rock art sites Understanding 3D imaging Some results and Discussion Conclusion Outline

3 Textured 3D models: 3D media model

4 High-resolution 3D imaging for rock art sites Site closure or limited access Researchers: examine, measure, compare Control: signs of deterioration Tool marks: verify hypothesis related to art history Virtual restoration: graffiti removal Display is interesting for both public & researchers Immersive 3D VR theater View model in a more natural hypothetical illumination context

related to art history Virtual restoration: graffiti removal Display is interesting for both

5 What to record? Rock art: walls, crypts, grottos Formed naturally or created by people Rock formations and hence irregular shapes Paintings (pictographs) Carvings incisions (petroglyphs) Concretions stalactites/stalagmites (speleothems) 3D imaging or sensing: Explicit geometric measurement Dense sampling There is a match! Lots of details to be measured

and hence irregular shapes Paintings (pictographs) Carvings incisions (petroglyphs)

6 Formed naturally or human activity

7 Some projects: rock art Caves, Crypts, Petroglyphs, Pictographs: Altamira Lascaux Lascaux II Cosquer: EDF 1994 Tomb of St-James (Arcosolia room): NRC 1996 Carpiniana: SIBA+NRC 2001 Baiame Australia And many more

EDF 1994 Tomb of St-James (Arcosolia room): NRC 1996

8 Neolithic cave Grotta dei Cervi (Stag), Italy Porto Badisco, Southern Italy (5 th millennium BCE) N, E Depth: 26 m, RH: 98%-99.99%, 14 C - 18 C Many pictographs (Guano, Ochre) and speleothems and some petroglyphs 3 corridors about 300 m each, < 6 m diameter Very little information available; discovered in 1970 Pictographs in central corridor have deteriorated since Measures to slow down the decay: Closure of cave to limit human visits Restrict air flow with doors

99%, 14 C - 18 C Many pictographs (Guano, Ochre) and speleothems and some petroglyphs 3 corridors about 300 m each, < 6 m

9 Grotta dei Cervi: 1970 s survey 26 m

10 Working in the field Environmental: Temperature Humidity Particles, etc. Operational: Power Safety Scheduling Stability Accessibility/coverage

11 Combination of Multiple Techniques Reference frame, major elements and outlines Existing drawings and floor plans Surveying Semi-automated modeling from aerial and ground images Some data available Automated modeling from image sequences Fine Geometric details Laser scanning Raw data only 4 chambers

modeling from aerial and ground images Some data available Automated

12 Active sensing Technology Triangulation (angle of reflected light): Controlled illumination for excellent contrast In practice, up to 10 m ( pts/s) Errors in $$/$ Time of flight (delay/phase/beat frequency): Laser beam / Medium to Long range entire sites > 1m ( pts/s) Errors in $$$/$$/$ $=10K, $$=100K

Errors in µm/mm @ $$/$ Time of flight (delay/phase/beat frequency): Laser beam /

13 CAD Acquiring 3D information : White Light pattern projection/ Laser scanner : Stereoscopic Correspondence TOF Laser scanner

14 The operator is part of the chain! polygon model polygon model Same 3D data & modelling software; different operator

15 The Coverage and resolution problems Solutions: Multiple-view acquisition/registration/integration Well established algorithms Increased time Field-reconfigurable range camera On-site calibration Resolution, uncertainty, accuracy verification Single scanner head??? Yes : NRC Canada Big-Scan system

time Field-reconfigurable range camera On-site calibration Resolution,

16 NRC Canada Big-Scan system

17 Big-Scan: Large field system Triangulation system with variable resolution: - lateral: z - depth: z 2 Error z 3D Scanner x

18 Standoff: 0.5 m - 5 m 0.2 Field of view: degrees 0.12 Depth uncertainty : meter 0.08 Size of each image : 0.04 up to 4K 4K pixels 0 Lateral sampling: 0.2 mm to 2 mm Acquisition rate : D+I points per second Depth uncertainty (mm) Scanner Spec. Close range performance Distance (m)

19 Some results Lateral resolution 0.2 mm Depth uncertainty 0.08 mm

20 Grotta dei Cervi, Italy

23 VR theater

24 1970 analog photo to D model!

25 3D Model building CONCLUSIONS Most of the time spent goes into finding next best view Problems: Vibrations, Material effects Site safety: people and environment R&D issues: Speed: texture and 3D modelling Took NRC technologies development for the Mona Lisa project and adapted them to the Grotta dei Cervi! 3D model completion: The first scans: end of 2009 Spring 2009: return with medium volume scanner to connect the rooms together

26 The team

27 3D, SCIENCE ET PATRIMOINE CULTUREL 3D, SCIENCE AND CULTURAL HERITAGE Metz, France Novembre 2008 Computer Aided Modelling and Exploration of the Grotta dei Cervi and Virtual Reconstruction of the Broken Frescoes of the Assisi Basilica. SAMEDI 22 NOVEMBRE 15H15-16H15 Visioconférence: Pr. Éric PAQUET Conférence: J-Angelo BERALDIN et Adriana BANDIERA

3D BYZANTINEB 3D ARCHAEOA. 3D Crypts. 3D Sub Divo RCHAEO

3D BYZANTINEB 3D ARCHAEOA. 3D Crypts. 3D Sub Divo RCHAEO Electronic Imaging 2003 20/01/2003 Electronic Imaging 2003 Santa Clara, California Videometrics VII Wednesday 22 January Santa Clara, USA J-A Beraldin(1), Picard(1), El-Hakim(1), M. S.F. G. V. Valzano(2),