modeling and visualization of aboriginal rock art in the baiame cave sabry el-hakim, michel picard...

Modeling And Visualization Of Aboriginal Rock Art in The

Baiame Cave

Modeling And Visualization Of Aboriginal Rock Art in The

Baiame Cave

Sabry El-Hakim,Sabry El-Hakim,

Michel PicardMichel Picard

Visual Information Visual Information Technology,Technology,

National Research National Research Council CanadaCouncil Canada

John FryerJohn Fryer

School of Engineering, School of Engineering,

University of University of Newcastle, AustraliaNewcastle, Australia

Where is Newcastle?Where is Newcastle?

OutlineOutline

1. Motivation and requirements.2. Proposed approach.3. Movie4. Some Details5. Results of Modeling the Baiame cave.6. Conclusions.

Why 3D Modeling / Digital Archiving for Cultural Heritage ?

Why 3D Modeling / Digital Archiving for Cultural Heritage ?

•Documentation in case of loss or damage

•Educational resource

•Visualization from new viewpoints

•Interaction without risk of damage

•Virtual tourism and virtual museums

Australia’s Aboriginal Rock ArtAustralia’s Aboriginal Rock Art

• World’s oldest art • Unprotected - Fast deteriorating• Inaccessible – Not enjoyed by most • Why Baiame?

The Baiame Cave LocationThe Baiame Cave Location

RequirementsRequirements

•High geometric accuracy

•Complete detail

•Photo-realism

•Low cost

•Portability

Current TechniquesCurrent Techniques

SurveyingPhotogrammetry

Standard Mapping

Laser ScanningAutomated Image-Based

Emerging

Direct TracingPhotographyField Notes

Traditional Rock Art

2-D Only 3-D on selected points only

Potential full 3-D with photo-realism

Comments and ObjectiveComments and Objective

•The efficient integration of image-

based modeling and laser scanning,

each where best suited, for

recording Aboriginal rock art is the

objective of this research.

Technology SelectionTechnology Selection

Image-Based Methods

•Low cost sensor

•Require features **

•Difficult on fine details

•Object size independent

•Manageable data size

•Portable

Laser Scanning

•High cost sensor **

•No features required

•Give fine details

•Object size a factor

•Huge data size

•Bulky

** The problems for this application

Error Sources : Image-based, Laser-scan and Geometric

Configurations (see example)

Error Sources : Image-based, Laser-scan and Geometric

Configurations (see example)

B/D Ratio

Mainly B/D (base/depth) ratioB is the component parallel to the object.

Images 1-3 Good Images 3-2 Poor

The Proposed SolutionThe Proposed SolutionLaser Scanning

3D Geometry CaptureDigital ImagingTexture Capture

SurveyingReference Frame

Bundle Adjustment

Texture RegistrationWith 3D Geometry

Post Processing- Compression & editing

- Texture matching

Visualization

Scans Registration

Noise filtering

Rock Art in Baiame Cave - The MovieRock Art in Baiame Cave - The Movie

Problems With Rock Art Modeling (Image-Based Techniques)

Problems With Rock Art Modeling (Image-Based Techniques)

• Difficult to find ideal locations to take Difficult to find ideal locations to take the images (rocks, trees, water,..etc)the images (rocks, trees, water,..etc)

• Insufficient features in multiple imagesInsufficient features in multiple images

• No geometric constraints to increase No geometric constraints to increase automationautomation

Problems With Art Rock (Laser Scanning)Problems With Art Rock (Laser Scanning)

• Texture / color acquisition: most Texture / color acquisition: most scanners do not provide good solutionscanners do not provide good solution

• Registration of scans and scans with Registration of scans and scans with texture: require featurestexture: require features

• Noise level, particularly for lower cost Noise level, particularly for lower cost scanners: Noise level can be the same scanners: Noise level can be the same size as many geometric details (the size as many geometric details (the rocks)rocks)

Best SolutionBest Solution

• Geometry from laser scanner to get Geometry from laser scanner to get all geometric detailsall geometric details

• Texture from a separate high Texture from a separate high resolution digital cameraresolution digital camera

But we must have accurate registration, even without common features or targets, otherwise:

But we must have accurate registration, even without common features or targets, otherwise:

Features spanning two images may not align

Geometry and color do not match

Texture MappingTexture Mapping

Correct registration but texture color / lighting must be corrected Uncontrolled

illumination

The Baiame Cave , Data CollectionThe Baiame Cave , Data Collection

Riegl® Z210i

Leica® Total Station

+ Nikon® Cool Pix digital camera

SurveyingSurveying

Useful Points

Not useful: no detectable geometry in the 3D model

Image LocationsImage Locations

Available image locations

Poor geometric configurations

Top view

Commercial Software ToolsCommercial Software Tools

• PolyWorksPolyWorks® 8 8 3D Modeling

• ShapeCaptureShapeCapture® 5 5 Bundle Adjustment

• 3ds max3ds max® 5 5 Rendering

• Adobe PremierAdobe Premier® 6 6 Movie Editing

Accuracy NumbersAccuracy Numbers

Laser scanning: +/- 30 mm

Surveying: +/- 2-3 mm

Bundle Adjustment: X: +/- 13 mm, Y: +/- 9 mm, Z: +/- 11 mm

Image-Based ModelImage-Based Model

Scanner ModelScanner Model

Comments on the ResultsComments on the Results

The results of the laser scanner were noisy and did not capture all fine geometric details. This caused problems with registration, particularly since the data had to be smoothed to reduce the noise.

The image-based model was not detailed enough and resulted in unrealistic 3D experience.

ConclusionsConclusions

•Our approach uses some surveying, laser scanning, digital images with a bundle adjustment to register the texture with geometry without targeted points.

•The resulting model is realistic and was created in a short time at low cost.

• It is still not clear what accuracy is really needed. Although rocks do not need to be modeled with high accuracy, poor accuracy will result in visible registration errors.