How to Use Photogrammetry to Create 3D Models
of Cultural Heritage Objects
New England Museum Association
Veteran’s Day, November 11, 2016
Who We Are
The Digital Ark, Corp. (TDAC) is dedicated to preserving, stewarding and sharing cultural heritage by capitalizing on emerging technologies in
innovative ways. As designers, developers, archivists, photographers,
producers and programmers, we approach every aspect of the digital
archiving process with the utmost degree of precision, usability and
quality control. TDAC focuses on optimizing workflows and integrating
tools which facilitate the design and production of end-products ranging
from interactive kiosks and virtual reality to dynamic collections portals
and fine-art reproductions.
Company Background
Experience
• 30 Years in Digital Media and Archiving
• Preservation + Architectural Photography
• Website + Database Development
• Graphic Design + Multimedia + Print
• 3D Animation + Film + Video + Audio
• Digital Archiving Systems
What Is [Stereo]Photogrammetry?
Photogrammetry has been defined by the American Society for
Photogrammetry and Remote Sensing (ASPRS) as the art,
science, and technology of obtaining reliable information about
physical objects and the environment through processes of
recording, measuring and interpreting photographic images
and patterns of recorded radiant electromagnetic energy and
other phenomenaInvolves estimating the three-dimensional
coordinates of points on an object employing measurements
made in two or more photographic images taken from different
positions. A special case, called stereophotogrammetry,
involves estimating the three-dimensional coordinates of points
on an object employing measurements made in two or more
photographic images taken from different positions.
History of Photogrammetry
The developments in photogrammetry, from around 1850, have
followed four development cycles [Konecny, 1985]. Each of these
periods extended about fifty years. These cycles include:
• Plane table photogrammetry: circa 1850 - 1900
• Analog photogrammetry: circa 1900 - 1960
• Analytical photogrammetry: circa 1960 - present
• Digital photogrammetry: this is just beginning to be a
presence in the photogrammetric industry
How Is Photogrammetry Used Today?
• 2 basic types of photogrammetry: aerial and close-range
• Used in archaeology, conservation science, museum studies,
art, history, epigraphy and ancient document studies
• Documentation, visualization and preservation of cultural
heritage objects and sites
• Conservation planning and restoration recording—enables
conservator to understand in 2D and 3D key features and issues
• Analysis of archaeological materials and representation of
archaeological data
Laser Scanning Vs. Photogrammetry
Cloud Point Model - Courtesy of Autodesk
Laser Scanning Vs. Photogrammetry
Laser Scanning Vs. Photogrammetry
Source - Lanmar Services
Photogrammetry Examples
Natural History
• Komodo Dragon Sculpture
• Triceratops Horridus
• Mandarine
Sculpture
• Bronze Statue of Napoleon in Cherbourg
• Place de la Nation-The Triumphe of the Republic
Architecture
• Piazza di S. Maria in Trastevere
• The Gardens of Marqueyssac
• Battleship Island [GUNKANJIMA]
Photogrammetry Examples
History
• Stereoscopic camera by Heinrich Ernemann
• De humani corporis fabrica
Our Work
• RIHS - Roger William’s Compass
• RIHS - Map of Providence Powder Horn
• East Providence RI - WWI Centennial
• Mystic Seaport Scrimshaw
• Lion Figurehead
More https://skfb.ly/VTyN
Why Consider Photogrammetry?
• Access to More of Your Collections
• More Detail, More Control
• Spatial Understanding
• More Educational Opportunities
• Crowdsourcing and Collaboration
• Measurements - Exhibit Planning
• Monetize Objects - 3D printers
• Virtual Reality - It’s Coming
• The WOW factor - Kids get it!
Nina Leen
Why Consider Photogrammetry?
Time to Create
5 Minute Break
Before You Shoot
Object Evaluation - Inspect objects closely prior to shooting
• Does it have reflective surfaces?
• Chrome, mirrors or high specular surfaces
• Are there transparent materials?
• glass, transparent plastics, etc.
• Is the surface solid or is made up of “holey” parts?
• Problematic objects; baskets, loose weave fabrics, screens, etc
• Does object have thin parts
• Problematic objects; sailing ship models, intricate costumes, etc.
• Does the object stand upright?
• Will you need to build a rig to keep it steady?
• Is the object elongated?
• Will the cameras depth of field maintain focus over length of the object?
• Is it a 3 sided or 4 sided object?
• a 4 sided object requires more images and more processing
How To Capture Images
Equipment
Cameras & Lenses
• 35mm DSLR or mirrorless camera with 16 megapixels or better
• Manual control of aperture and shutter speed
• Mirror up function or mirrorless for sharpness
• Flash sync
• 50mm Fixed lens or equivalent
• Sharp - Glass Aspherical Element
• Low distortion and vignetting
• Multi-Layer coating produces good contrast
• With a short focal distance (18”)
• Low color aberration
Equipment
Sigma 50mm Art Lens and Canon 5Dsr 50 megapixel camera
Equipment
Olympus OM-D EM Mark II 16 megapixel camera with 30mm fixed lens
Lighting & Equipment
• Indoor Set-up:
• Digital light shed/tent
• Flash/Strobes or low heat LED lights
• Tripod with mechanized head
• Scale bars/color target
• Archival museum wax and object stands
• Turntable
• Handheld light meter
• Camera slide
• Additional Outdoor Set-up:
• Mega Mast Tripod
• Drone
Lighting & Camera Equipment
Lighting & Camera Equipment
Lighting & Camera Equipment
How To Capture Images
• Maintain consistent overlap of images at least 20%
• The more complicated an image, the more shots
• Minimum 30 shots per row - 60 shots ideal
• Capture 2-3 rows of images:
• 30º degree increments
• Use reference grid or registration markers
• Light from the sides or above to avoid refections or hot spots
• Use polarizing filters to reduce glare
How To Capture Images - 2 Rows
Computer Processing Workflow
• Calibrate lens
• Process images in photo editing program
• Rename Files to identify what row shots came from
• Create 2 sets of images
• A natural balanced image—this will be used for final texturing
• A high contrast saturated version—this will be used to create the point cloud/mesh
• A matted version of the object maybe needed for intricate objects
• Import high contrast images into photogrammetry software
• Generate a point cloud
• Generate mesh at target resolution (200,000 polygons for the web)
• Texture map mesh with naturally balanced images
• Export to 3d model format such as .obj
Computer Processing Workflow
• Software models the camera’s optical system, the camera’s
positions and orientations for each photo, and a sparse cloud of
points representing matches of the subject’s features as seen by
multiple images.
• Software uses multi-viewpoint stereo algorithms to build a dense
point cloud, which can be transformed into a textured 3D model.
• Software employs surfacing algorithms, employing the dense
cloud’s 3D point positions and the look angles from the images to
the matched points, to build the geometrical mesh.
• A texture map is calculated from the pixels of the original images
and the knowledge of how those pixels map onto the 3D geometry.
Software
Photogrammetry:
• Autodesk 123D Catch uses mobile device as camera - Free Online Processing
• Our recommendation: Agisoft PhotoScan Educational - $59, Standard - $179 & Agisoft PhotoScan Pro - $3499 - Local Processing
• Autodesk Remake (Formerly Memento) - $300/year
Online Processing & Local Processing
Other Software:
• Turntable Software
• Lightroom, Photoshop or CaptureOne
• Blender - 3D Modeling - FREE
• Meshlab - Model repair - FREE
• MeshMixer - Basic Modeling Utility - FREE
Pros + Cons
Pros:
• Cost-effective, efficient and portable tool for documentation and conservation
• High level of detail, precision and accuracy
• Limited number of digital images can be captured with standard digital camera in a relatively
short period of time
• Archive-friendly: digital images and their associated metadata can be archived and used later to
re-generate the 3D model
• A photogrammetry shoot yields 3 products
• Multiple 2D photos for documentation, Virtual 360 option and a 3D model
• 3D models can be sampled for display on websites, mobile devices, kiosks, and VR or animation
for film or video
Cons:
• Does not work well with reflective and transparent surfaces
• Requires evaluation and testing of objects
• Learning curve - Thank Goodness for YouTube
Thank You
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www.TheDigitalArk.com
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