Integrating Spectral and 3D Imaging for Monitoring ...€¦ · Integrating Spectral and 3D Imaging...
Transcript of Integrating Spectral and 3D Imaging for Monitoring ...€¦ · Integrating Spectral and 3D Imaging...
Integrating Spectral and 3D Imaging for Monitoring Heritage Objects E. Keats Webb
Conservation Documentation
Scientific Imaging
CollectionsPhotography
Measurement and Material Identification
Exhibition and Catalogue
Record Condition, Inform Care, and Increase Understanding
Smithsonian National Museum of the American Indian Inka Qero (NMAI 16/3605)
Museum Imaging
UV-Induced Visible Luminescence Visible Reflected IR
Smithsonian American Art MuseumUntitled (SAAM 1986.65.339)
Spectral and 3D Imaging
Accessible Devices and Workflows
Smithsonian American Art MuseumUntitled (SAAM 1986.65.339)
Visible
Reflected IR
Smithsonian American Art MuseumUntitled (SAAM 1986.65.339)
Camera Modification• Single wavelength conversion • Full spectrum conversion • Monochrome conversion
Dust reduction filter
Sensor
IR blocking filter
Microlens
Blue color filter
Photodiode and Silicon Substrate
Modified Consumer Digital Camera
Camera Characterization
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Spectral Response • Spectral response showed
higher sensitivity in the shorter wavelengths
2D Image Quality • RAW processing workflow that accounts for the camera modification
• Residual pixel-level pattern
• Increased noise
• Increased effective resolution but risk of aliasing
Wavelength selection Object materials
& Optical Properties
Camera Sensitivity
Filter Transmission
Illumination Output (SPD)
Depth of Field and Sharpness Depth of field is not well defined for 3D reconstruction
f/5.6 f/11 f/32
Work to Quantify Effective Depth of Field • Linking 2D image quality assessment to 3D reconstruction
• Permissible blur:
• FADGI star rating requires smaller value
• 3D reconstruction tolerates larger value
• Test object is not representative of heritage objects
Summary
Wavelength selection with the modified camera• Increase local contrast to improve 3D reconstruction
Understanding depth of field for 3D reconstruction • Increase sharpness to improve 3D reconstruction
Camera Characterization
Linking 2D image quality to 3D reconstruction
Acknowledgements Museum Conservation Institute
Robert Koestler, DirectorPaula DePriest, Deputy Director
Smithsonian American Art MuseumAmber Kerr, Chief of ConservationHelen Ingalls, Retired Objects ConservatorAriel O’Connor, Objects Conservator
University of Brighton Roger Evans, Reader
University College LondonStuart Robson, Professor of Photogrammetry and
Laser Scanning Lindsay MacDonald, Honorary ProfessorDanny Garside, PhD StudentBen Sargeant, PhD Student
Analytik LtdIan Laidlaw, Managing Director & Founder