Experiencing Legacy ASTM E57 for Heritage

A 1.469Mb PDF of this article as it appeared in the magazine complete with images is available by clicking HERE

There are an infinite number of mechanisms in the history of visual documentation and communication, dating back thousands of years that humans have used to spark an idea, a memory, or an experience. The question that I have asked myself and readers of my blog in several ways is: Why? What is the relevance of laser scanning as a tool, or other forms of 3D documentation in the context of human legacy?

Because we interpret the world in 3D, it makes sense that modern computer graphic technologies are facilitating that experience. Unfortunately, our current architectural archival process in the United States through the National Historic Register has yet to adopt 3D laser scanning as an acceptable data-type and continues to use HABS/HAERS/ HALS 2D documentation which can include CAD based drawings and photos of a specific format. While 2D documentation has been relied upon as a time-tested format for archiving, there is a fundamental component that is lost in this method–The `Experience’.

What laser scanning and other forms of 3D visual media provide is a close, visual facsimile to the reality that is perceived by our consciousness at any given moment. In the discipline of art and painting, gesture is the component of expression and emotion. Master artists have many ways to capture the experience of a moment in time. Their ability to create an aesthetic experience is remarkable and takes years of training. With modern scanners and other 3D image capture devices, a relatively brief amount of training a competent technician can document any subject of any complexity with very little need for viewer interpretation. Additionally, when provided with a software viewer of some sort, the audience can experience the subject from any vantage point and draw their own conclusions based on a nearly flawless rendering of said subject.

Where the Library of Congress fails the laymen, historical researcher is in the ability to visualize an architectural subject in full context of site, scale, depth, and other aspects of a fully perceived, near holographic interpretation, such as can be provided with 3D imaging systems.

In the endeavor to make accessible 3D visual technology for future generations, there has been a committee organized to create an archival format for 3D laser scan data. This format is formally known as the ASTM E57 format and the committee is less formally known as the E57 Heritage Committee, of which I have been fortunate enough to become a contributing member.

What these discussions typically entail is strategizing what sort of data should be embedded within the E57 format as it relates to historical preservation applications and subject matter. The great news about this format is that it is not limited to containing only laser scan data. E57, much like other scanning file formats can include image and ASCII text information. This translates to the possibility of including data mirrored from the standard HABS/HAERS/ HALS documentation submissions, at least to some degree.

A Vision of our Future
Imagine a National Archive submission that contains all the documentation of a particular historical site, packaged in a single file format. Further, this format would include metadata such as notes from field surveyors and would be encoded in such a way that 50 years from now, we could know with certainty that this open-source, digital file could be opened by any software that would be on the market and would be engineered in such a way that factors such as data corruption and bit-rot would not be of great concern. It would provide those who would study the legacy of our modern infrastructure in the future, the assurance that the past was secure; that their architectural history could be viewed, and measured, in complete 3D context without needing to interpret 2D drawings correlated with photos from a limited number of vantage points. Additionally, these ingenious and robust E57 files would be rich in content, but not in file size with the help of innovative, compression formatting. Sound too good to be true? Some of this vision is already a reality.

Where we are going with E57 Heritage Format?
The goal of the E57 Heritage committee is to provide a medium for long-term retention of data for use in historic preservation and construction documentation. The latter has value to the facility manager which is, in many ways, a historian in a pragmatic context. I find it useful to talk about E57 as a "container" for a variety of information. Because it is open-source, there exists much room for extensibility; another great benefit to leverage from this data format. According to Ken VanBree, lead heritage committee coordinator and owner of eBuilts, "The goals is to take a collection of digital data gathered from a diverse set of sources and preserve it in a way that ensures it will be usable in generations to come."

Further, the E57 Heritage format is being designed to contain the following:
LiDAR scan data (point clouds) taken from a variety of manufacturer’s equipment
Photographs taken from a diverse set of sources for which the location of the camera can be known to a reasonable accuracy and,
Metadata about the point clouds and pictures such as registration accuracy and field conditions.

Issues that have been identified for enhancement to the existing E57 format include:
Enhanced capability for embedding photos. The current standard specifies four types of 2D images that can be incorporated into the standard: Visual Reference, Pinhole, Spherical, and Cylindrical. The images thus far can only be in .JPG or .PNG format. Enhancements could include .TIF/TIFF or RAW to account for National Archival standards.
Embedding project metadata which is above and beyond E57 specific metadata. Current field practices include metadata such as notes describing what is in the field, registration accuracy, and info from scan collection-to-processing. Using E57’s extensibility, data such as spreadsheets, Word/Pages documents, PDF, and others could be defined in the XML section of the E57 file format and stored as binary data within the standard. To flush out the metadata process, Aliza Leventhal, Corporate Librarian/Archivist and CAD/BIM Taskforce Co-Chair of the Society of American Archivists contributes that, beginning with a relatively small pilot project having historical significance, is a logical first step in testing the E57 system and developing metadata format standards. Currently, the committee is exploring project candidates for that purpose.
Deciding the long-term archival format: ASCII vs Binary. This is perhaps among the more complex decisions that will need to be made. Questions posed by committee member, Justin Barton, HDS Product Marketing Specialist at Leica Geosystems, include whether binary format will be accessible 100 years from now. The issue of legacy is important and the committee will be determining how the initiation code will read the data as well as whether this code will be embedded within the same E57 shell for redundancy. Additionally, binary is stored with error detection capabilities which supports the minimization of data-corruption/loss (bit-rot) with the eventual goal of being able to open these files decades from their initial archiving. Technology and software versions will change over time, therefore it is essential that, as much as can be anticipated, decisions are made that support legacy of this data. ASCII files are robust in size and while simple in format, have some disadvantages that binary compensates for. Again, a complex decision.

"Curation" is yet another topic that is relevant to this E57 Heritage format dialogue. Who will keep watch over this data? Who will ensure the data is updated over time? Will the Library of Congress find funding to expand their server archival capabilities to manage the heavy lifting of laser scan data? These and many more questions will undoubtedly present themselves as this effort moves forward. All in good time I suppose. What I enjoy about this process is simply the fact that it is in fact moving forward. We are collectively acknowledging the extraordinary benefits of archiving in 3D and simultaneously, considering the best possible methods to accomplish this.

It has been a privilege to serve on this committee thus far. As a final `epilogue’ I leave you, faithful LiDAR News readers, a vision to consider. Science fiction?

We think not.

Our Near Future…
She sat in front of the hologram, derived from antiquated laser scan data, lazily spinning what once was known as the "Sydney Opera House;" a monumental achievement in architecture lost to the Great War of 2073. She could feel the haptic response from the 3D image and ran her fingers over the smooth rooftops and soft, fluffy, landscaped flora surrounding the represented structure. Panning through the archives, hundreds of historical sites that no longer existed illuminated before her in slow, ethereal rotation. Many built from impermanent materials, lost to the elements over time. Some lost by natural disasters or the malice of political and religious organizations.

Her father, an architect who had once visited the Opera House in person gave her a visual tour and explanation of the design intent while also pointing out where he stood when proposing to her mother.

"Print. She vocalized to the Visualizer " Kiosk at the New World Archives. A humming indicated the 3D printer bay began its scaled, recreation process of the infamous Opera House…a keepsake for her shelf marking the beginnings of her heritage.

D. Huber, "The ASTM E57 File Format for 3D Imaging Data Exchange," The Robotics Institute, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213.
MacCurdy, Edward; "The Notebooks of Leonardo Da Vinci", Konecky & Konecky 72 Ayers Point Road, Old Saybrook, CT 06475. All Rights Reserved.
E57 Information: http://www.libe57.org

Paul Tice is the CEO of ToPa 3D; an Oregonbased remote sensing data visualization firm specializing in 3D laser scanning, 3D modeling, and drone technologies.

A 1.469Mb PDF of this article as it appeared in the magazine complete with images is available by clicking HERE