In the last decade, 3D documentation has emerged as the pre-eminent technology to support heritage preservation around the world.
More recently, the technology has evolved to impact digital interpretation as well. Advances in preservation technologies are aligning with those in interpretive tech, so bridging the two to create virtual experiences and kiosks is finally beginning to be possible. This post will describe two common 3D documentation approaches and related resources for institutions considering leveraging this technology.
What is Laser Scanning?
Laser scanning enables a large quantity of three-dimensional measurements to be collected quickly. Laser scanners are devices that can be placed on land or on aircraft such as planes and drones. The scanners measures distance by systematically illuminating a target with a laser light, and recording that data. The point cloud is the raw product of a survey. It contains a large number of coordinates that detail every aspect of a surface, measured in microns. There are 25,400 microns in one inch. These points form the skeleton over which a skin can be rendered to create a recognizable 3D model.
Laser data is collected into proprietary systems, so the data will require messaging before it can be exported in a useful and shareable product. It can also be affected by environmental factors like humidity. Attention must also be paid to how the scans are registered. Though individual scans may be really accurate, the finished model can have a lot of error due to the registration process. Be sure to evaluate the implications of these factors, as well as the scale of your project when examining the appropriateness of this technology.
What is Photogrammetry?
Photogrammetry works by taking many images of a scene from different locations using standard digital cameras (there are even smartphone apps) and then processing them through programs to determine the exact location from which these photos were taken. When the positions of the camera are known, specialty software looks for common points in two or more photos to determine where objects exists in 3D space. It can still produce a very detailed virtual model. The technology is useful on a small scale, to document objects or fragments of architectural detail on buildings. It can be used for more frequent visual detection of deterioration for at-risk heritage resources, at lower costs than laser scanning.
In terms of accuracy, photogrammetry can give repeatable measurable results well in the sub-mm range, with reports of repeatable measurements in the 5 100ths of a mm. Photogrammetry has an advantage over laser scanning in terms of archiving because archiving image sets is well understood.
As with laser scanning, the quality of a product of photogrammetry is determined by how correctly it was shot and processed. A good looking model can still have a lot of error.
What questions can 3D documentation answer?
Laser scanning, supported with photogrammetry, can provide critical insight into a site’s built heritage that cannot be accomplished as efficiently by any other means. These include the following:
- How quickly a feature is changing. Laser scanning can contribute to a detailed record where a feature, structure or site might be lost or changed forever. Is the architectural detail on the barge measurably fading at a faster rate than that of the main house or the garden mound? Laser scanning can help predict the rate of deterioration, and inform conservation priorities.
- How one feature in the landscape relates to another. What is the proportion of an institution’s grounds to its built structures? Based on the contour of the landscape, how will sea level rise affect the estate over time? Laser scanning can help inform study of the overall cultural landscape–how it was fashioned and how it compares to the surrounding landscape. It can also uncover previously unnoticed archaeological features in a landscape covered in vegetation or woodland.
- The size of a structure. Laser scanning provides pinpoint accuracy regarding dimensions of objects and structures. This can be useful in planning for preservation projects by contributing to a record before renovation of a structure or landscape.
- Improve accessibility. For tall structures, a frieze, tiling, or other architectural detail may not be entirely visible from ground level. For others, environmental barriers may block access. Often, objects in museums are blocked from close inspection and certainly from touching. A 3D scan can replicate the proportions and form on an object for access on digital platforms.
- Aid expert understanding. Because of the detail it is able to capture, elements of an object or structure can be enlarged and examined on a virtually unlimited scale.
- Improve engagement with the general public. Models produced as a result of scanning can be incorporated into interpretive kiosks and digital tour apps for mobile devices, allowing the public to manipulate, enlarge and examine objects from all sides. This can further enrich their connection to the site/objects and allow them to share their experiences through the web.
- Replication. An accurate model is useful for producing a replica for display, or as a replacement in a restoration scheme. This could be useful in milling replacement replicas of the peacocks for the marine garden or sculpture on the barge that is at risk due to climate. Models can also be used by educational departments to 3D print objects as part of a handling collection.
Universities with 3D Documentation Programs
University Partners are highly aware of the grant landscape for laser scanning projects and are willing to collaborate on funding proposals. They also have excellent reputations for understanding how this technology can be applied to the entire range of cultural heritage documentation, preservation and interpretation.
In turn, universities benefit from a partnership with your institution because their students will have access to a living laboratory of historic structures, objects and landscapes to capture and evaluate. Here are a few universities that are capable of 3D documentation projects:
Ball State University Hybrid Design Technologies, Institute for Digital Intermedia Arts They have performed interesting projects on sculpture related to museum interpretation.
The University of Arkansas Center for Advanced Spatial Technologies describes its approach as “strongly multi-disciplinary and global in scope with current active research efforts throughout North America, South America, the Middle and Near East, and Europe.” The program is funded through grant projects.
Oregon State University Pacific Slope Archaeological Laboratory focuses on archaeological assets. Their site lists rates for services and provides interesting online video about the applications of their work.
The University of Michigan 3D Lab provides 3D capture and printing as part of its processes. They can assist with all phases of projects including planning, design and development.
In 2012, the University of Florida Historic Preservation Program launched the Envision Heritage initiative with the mission of exploring how new and emerging technologies can be utilized to document, conserve, and interpret historic sites.
The University of South Florida Alliance for Integrated Spatial Technologies (AIST) is a Research and Education Support Unit in the School of Geosciences, College of Arts and Sciences, at the University of South Florida. Its research interest is “preserving and protecting the world’s cultural and natural heritage through education and global engagement.”
Q: How will I be able to access and use the file?
A: You could use Autodesk Recap (subscription; $300/yr – Smithsonian uses this) to access the actual point cloud and MeshLab (open source) for solid models, or Rhino3D ($1,000 for a license). The partnering institutions are willing to work out a plan to offer training to staff on the use of these technologies as well. This will empower the organization to make better use of the data and learn to capture small-scale scans for predictive conservation modeling.
- How large might the file(s) be?
A: File sizes vary by the scale of the object and resolution. Estimates regarding the point cloud for the are about 15 GB. A solid model would be more than 100 GB depending upon the level of detail. Video animations can be 1GB or more depending on length. These are large, but still manageable sizes to store and access.
Q: How often would scanning need to be done to track preservation/conservation issues?
A: This will take time to determine. Laser scanning and photogrammetry could be used to focus on specific, collectively decided target areas and not record the entire structure each time. That would decrease time in field, processing, and cost. Of course, time intervals would depend on what we are monitoring for, and would be informed through a regular visual analysis by the conservation team, including observed rate of deterioration due to cyclical tides, storm events, etc.
Q: Can we use the resulting animated graphic in 360 photo tours?
A: The partner institution can provide the point cloud or solid surface file in a number of different formats. 360 tour vendors could integrate a 3D model so that it can be opened within the tour as a web-poi. For an off-line version (kiosk version) it may be possible to have a normal poi (point of interest) featuring still angles of the 3D barge that could be scrolled through giving the appearance of it rotating 360 degrees. Regal 360 could also just come out and photograph on top of the barge, but that still leaves the water side undocumented.
Q: Who owns the product(s)?
A: The point cloud, solid model and video animations should be specified as the sole property of your institution. A partnership should be structured so that the documentation partner would seek permission if they sought to publish anything regarding the work they did at your site.
To fully realize its value, a 3D documentation project should inform a broader systematic program of capture.
Universities that teach 3D documentation skills and execute related projects internationally can be valuable partners. This expertise can be leveraged for knowledge among staff, and provide learning experiences for university students and the general public.
Staff Workshop: A partner institution could provide an on-site workshop for relevant staff on photogrammetry. Staff would be instructed in the significance of 3D documentation, how to perform it, and how to use it to inform their work. This would include targeted documentation training that would allow staff to see differences between the images they capture, and those resulting from an initial high-resolution scan.
Community Day: Your institution could hold a community event to introduce local audiences (including students) to the technology and how the institution is using it. The event would showcase commitment to preservation while enabling the public to see heritage resources in ways (both micro and macro) that were previously impossible. This event could include the following:
- a presentation by the site and its partner institution to present preliminary data
- A demonstration of the documentation technologies.
- 3D printing of objects based laser scans that the public can touch and examine.
University Classes: University partners participating in 3D documentation could involve their students in the project. With an ongoing program of 3D digital scanning, a historic site could become a living laboratory for these students, providing a diverse array of architectural and environmental elements to round out their experience.
A university partner is particularly useful in identifying and acquiring grants for 3D documentation projects. The following granting agencies have expressed past interest in funding such projects:
- Knight Foundation: http://www.knightfoundation.org/communities/miami/
- National Park Service Preservation Technology and Training: http://ncptt.nps.gov/
- Florida Division of Historical Resources: http://dos.myflorida.com/historical/grants/
3D objects can be rendered in formats suitable to a wide variety of digital platforms, including the following:
Mobile Apps: For institutions investigating app development for enhancing the visitor experience. 3D models could be judiciously integrated into such an app, giving visitors the opportunity to manipulate select objects as part of a larger virtual tour. Additionally, USF AIST has student developers within its program that could potentially create a custom experience centered around 3D objects.
Sketchfab: Many institutions worldwide publish the renderings from their project portfolios to Sketchfab. Sketchfab is a leading online repository for publishing 3D and virtual reality content. It integrates with all major 3D creation tools and publishing platforms. Files can be uploaded in almost any 3D format, directly on sketchfab.com or using an exporter. Once models are on Sketchfab, descriptive text can be added and the resulting image can be embedded on any web page and are sharable on social media.
SCENE Webshare Cloud: SCENE WebShare Cloud is a cloud-based hosting solution from FARO that allows easy and secure sharing of scan data worldwide. It offers the ability to can see the renderings of structures or objects on an interactive map. It offers a the ability to include very detailed information, including measured distances, GPS coordinates, project descriptions. Though engaging for a general audience, it is most useful in working with contractors or managing entities. The degree to which it can zoom from estate map to details on architectural features also makes it a powerful computer-based solution to understand and analyze complex on-site conditions, including conservation issues. The base package for SCENE Webshare Cloud is $990, which includes 50GB storage.
YouTube: 3D documentation efforts can be rendered as video products that can be published to its YouTube Channel. These videos can be simple “virtual tours” of objects. They could also be stories about the process of documentation. Some of the University of Florida’s renderings can be viewed on the Envision Heritage YouTube Channel.
3D Documentation Specialists
Cultural Heritage Imaging (CHI) is a nonprofit organization, dedicated to advancing the state of the art of digital capture and documentation of the world’s cultural, historic, and artistic treasures. One of its goals is to create robust, low-cost imaging tools to document cultural heritage. It is noted for unique approaches to 3D documentation, its commitment to training people in these technologies, and its willingness to use social media as an outreach tool.
CyArk was founded in 2003 to ensure heritage sites are available to future generations, while making them uniquely accessible today. CyArk operates internationally as a 501(c)3 non-profit organization with the mission of using new technologies to create a free, 3D online library of the world’s cultural heritage sites before they are lost to natural disasters, destroyed by human aggression or ravaged by the passage of time. CyArk tends to focus on high-profile projects, supported by large grants.
3D Data Exchange
The ASTM E57 Committee on 3D Imaging Systems Sub-committee on Data Interoperability (E57.04) has developed an open standard for 3D imaging system data exchange. Working with partners to follow this standard is important to make maximum use of 3D products. The standard’s goals include the following:
- Open source
- Easy to use API, designed for common use cases
The E57 File Format for 3D Imaging Data Exchange is capable of storing point cloud data from laser scanners and other 3D imaging systems, as well as associated 2D imagery and core metadata.
The following documents will be helpful for partners assisting with 3D documentation projects
- Strategic Plan
- Historic Structures Reports
- Cultural Landscape Plan
- Related Archival Images
Participation in National Park Service Heritage Documentation Programs (HDP) would complement, inform and strengthen a built heritage site’s own 3D documentation efforts. In particular, a documentation project as part of the the Historic American Building Survey (HABS), or Historic American Landscape Survey (HALS) are options for documenting in this way. Much of the work of HABS is done by student teams during the summer, or as part of college-credit classwork. An institution could sponsor a student team in partnership with a university with an architecture program.
The measured drawings, photographs and reports produced from these programs are archived by the Library of Congress and made accessible through their online database. Efforts are being made now to connect HABS documentation to 3D documentation point clouds.
Bennett, Michael J. “Evaluating the Creation and Preservation Challenges of Photogrammetry-based 3D Models.” http://digitalcommons.uconn.edu/cgi/viewcontent.cgi?article=1057&context=libr_pubs
Kronkright, Dale. “Applications for Digital Photogrammetric Methods of Preservation Documentation of Historic Homes.” https://ncptt.nps.gov/wp-content/uploads/2012-11.pdf