Simple Tangible Interaction: An Illumination of Trajan’s Weapons Frieze and Open-source Models For Exhibition Development And Hands-on Storytelling

Todd Berreth, North Carolina State University, USA

Abstract

This how-to session and paper describes a tangible interactive installation at the Museum of the Imperial Forum in Rome, developed as part of an exhibition commemorating the 19th anniversary of the Emperor Trajan's death. The project was entirely manufactured via "maker" technologies, a laser cutter and 3-D printer; its interactivity was implemented through hobbyist electronics, a low-cost micro-computer and simple scripting. This project led to an effort to create a generic, open-source project, on how to build a similar installation with other curatorial content, using the same technologies and techniques. It's designed as a typical "do-it-yourself" tutorial, which tries to simplify the process of fabricating. It's a simple entry point to incorporating these modes into a user’s curatorial practice, testing their use, and potentially extending the project and its tutorials and fabrication plans, via open-source collaboration. Such work offers a compelling model for open-source exhibition development. Museums and cultural heritage researchers continue to experiment with emerging techniques to engage the public regarding cultural sites, archaeological artifacts, and museum collections. This happens increasingly through interventions using computational media, leveraging its unique affordances to enable new possibilities for interactivity and storytelling. Such communities are exploring these potentials to heighten visitor engagement, better communicate context and narrative, and generally to activate the experience and generate empathetic connections with the subject matter. While such modalities continue to spark the imagination of many curators and scholars, a barrier remains regarding learning curves and the expense of developing such engagements, which hinders communities from incorporating these modes into their toolkits. This suggests that there is a need to both experiment with new modes, and make it easier and less expensive for others to do the same.

Keywords: archaeology, tangible, open-source, haptic, museums, storytelling, how-to, tutorial

Introduction

Museums and cultural heritage researchers continue to experiment with emerging techniques to engage the public regarding cultural sites, archaeological artifacts and museum collections. This happens increasingly through interventions using computational media, leveraging its unique affordances to enable new possibilities for interactivity and storytelling. These include mixed and virtual reality experiences, location-based mobile applications, haptic interfaces, 3-D-printed reconstructions, projection mappings, and online virtual museums, among others. Such communities are exploring the potential of these techniques to heighten visitor engagement, better communicate context and narrative, and generally to activate the experience and generate empathetic connections with the subject matter.

While such modalities continue to spark the imagination of many curators and scholars, a barrier remains regarding learning curves and the expense of developing such engagements, which hinders communities from incorporating these modes into their toolkits. This suggests that there is a need to both experiment with new modes, and make it easier and less expensive for others to do the same.

In 2014, Duke University, the Museum of the Imperial Forum in Rome, and the City of Rome established a collaborative agreement, centering on an interdisciplinary study of a number of sites and artifacts connected to the 2nd-century Roman Emperor Trajan, including the Trajan Forum and its Basilica Ulpia. This was partially motivated by the approaching 1,900th anniversary of the death of the Roman ruler in 2017 and the planned commemorative activities and exhibitions related to the occasion.

A year before the anniversary, Duke University’s Dig@Lab, led by Professor Maurizio Forte, began an effort to design and build an exhibition which utilized a number of experimental technologies—this resulted a collection of four installations deployed in coordination with other planned exhibitions in the museum. Among these was a large-scale, 3-D printed model of the Basilica Ulpia, an augmented-reality application, a series of holograms revealing the digital reconstruction and narratives of the Basilica, and an interactive tabletop with haptic interface and a digital wall projection, which focused on explaining the Trajan’s Weapons Frieze, a prominent decorative feature above one of the entrance portals of the Basilica.

This how-to session and paper focuses on this last installation. A team composed of members of the Duke Dig@Lab, Professor Todd Berreth and research staff at North Carolina State University’s Visual Narrative Cluster, experimented with a number of inexpensive technologies to fabricate and develop this project. This included manufacturing the table and its component parts entirely via “maker” technologies, a laser cutter and 3-D printer, and then implementing its interactivity through hobbyist electronics, a low-cost Raspberry Pi micro-computer and simple Python scripting.

The effort produced an extremely inexpensive interactive table, which allowed visitors to physically handle 3-D-printed copies of fragments of the frieze and place them together into the “puzzle” of the scholarly reconstruction of the relief of the weapons. This interactivity triggered explanatory animations that described the iconography embedded in the frieze fragments, and contextualized the pieces in a large digital projection on the wall in front of the table.

Such a design effort led to a parallel effort to create a generic, open-source project, and set of instructions, on how one might build a similar installation with other curatorial content, using the same technologies and techniques. This project is formatted as as a typical “do-it-yourself” tutorial, which tries to simplify the process of fabricating and building such a system. This is then a friendly entry point to incorporating these techniques into a user’s curatorial practice, testing their use, and potentially extending the project and its tutorials and fabrication plans, via open-source community contribution and collaboration.

The Trajan Puzzle Project and Exhibition

Duke’s Dig@Lab and the Museum of The Imperial Forum pursued the difficult task of interpreting, making sense, and communicating to the public, some of the more than 40,000 existing fragments of Trajan’s Forum—an effort titled, the Trajan’s Forum Puzzle Project. Generally, the project aimed to create an innovative narrative experience that accentuated the cultural legacy of Trajan, and the period in which he ruled over the Roman Empire, through architectural and sculptural speculative digital reconstructions.

The project focused on a 3-D reconstruction and digital modeling of the Basilica Ulpia (the largest building of its kind in the 2nd-century Roman world) and a visualization of one of its prominent decorative elements, the Weapons Frieze. This frieze was a bas-relief panel adorning the eastern face of Basilica façade, near its main entrance. According to current interpretation, the Weapons Frieze consisted of 84 unique surface elements, 15 fragments of which still exist. The Duke team carefully analyzed the remaining original artifacts, and generated 3-D digital meshes of them via photogrammetric scans of the fragments, which were then 3-D printed as interactive artifacts in some of the exhibits. The existing artifacts are considered too fragile to be directly touched by the museum visitors, and much of the collection is not on display—such virtualized haptic interaction allowed a hands-on, immediate experience with the broader repository, which is still very rare in many archaeological museums.

The reconstructions, both of the overall building and the mentioned frieze, were visualized and expressed using diverse, multi-modal strategies. The same content was often communicated in redundant fashions, using different modalities and types of engagement. A core challenge of the project was to help the public perceive the museum artifact, in this case, a multitude of archaeological fragments dislocated from their original context and be able to place them into a comprehensible temporal and spatial narrative. The differing digital, analog, and haptic engagements allow the visitor a multi-faceted immersion in the subject matter, enabling them to make sense of the disparate relationships between the artifacts, understand a bit of the speculative and conjectural nature of the reconstruction process, position the fragments within a historic context, and form empathetic connections with the subject matter through active engagement and sense-making, via interactive strategies and physical touch.

Tangible Interactions in the Museum

The Trajan’s Weapons Frieze tangible installation was inspired by the success of recent hands-on exhibitions in prominent museums, such as the Louvre and the British Museum, which showed the importance of creating a visual and tangible narrative focusing on specific objects, and the potential empathy generated by individual interactions with the unique artifacts. The Chess Project (Cultural Heritage Experiences through Socio-personal Interactions and Storytelling) (Katifori et al. 2014), The Mapping Place project (Chu et al. 2015), and the The Belongings project (Muntean et al. 2015), all are excellent examples of interactive digital museum exhibitions which focus on the creation of visual narrative and storytelling, linked with specific artifacts. The last two of these focused specifically on leveraging tangible interaction, hands-on, touch-based contact with physical artifacts, to heighten visitor connection with the subject matter and to provide rich contextualization and interactive media engagements for the objects.

Tabletop-based tangible digital interaction within the museum setting has been explored for the last two decades (Hornecker, 2005; Patten et al., 2006; Shaer and Hornecker, 2010). Such projects are usually developed on specialized, often prohibitively costly, commercial hardware (such as Ideum multi-touch tables with proprietary physical object tracking software), or are produced as “one-off” idiosyncratic projects, with custom display and cabinet designs, unique tracking configurations, or elaborately engineered electronics systems. Custom projects leverage highly specialized design, fabrication, technology integration and programming skills, and access to workshop space and a wide range of tools and equipment, which are often unavailable to many exhibition development groups and cultural heritage research laboratories.

In a previous project, we developed an open-source design which would replicate the core technologies and affordances of optical-based tangible interaction tables (i.e. first-generation commercial tangible technologies such as the Microsoft Pixelsense, which uses back-projected displays in combination with tracked optical markers). We used inexpensive “digital-maker” fabrication techniques, open-source software, and consumer-grade hardware, which resulted in a design which would cost a fraction of the commercial devices. This project, the Tangible Interactive Table for Archeology (TITA) (Berreth et al. 2016), in many ways, was just the start of an ongoing effort to design, engineer, and develop a range of open-source hardware projects, which explore and support emerging tangible interaction paradigms in the cultural heritage and digital humanities spaces.

Various views of the self-made table. Figure 1: TITA (Tangible Interactive Table for Archaeology). Axonometric drawing, fabrication/construction photographs, conceptual renderings featuring Regium Lepidi Forum project

The general approach to all of these projects would be to only specify tools and fabrication technologies which might be found in typical makerspaces—simple hand tools, a laser cutter and 3-D printer. The specified fabrication materials would be generally available at local “big-box” home improvement stores, excepting easily available and relatively inexpensive electronics and other components, specified from a list of online-vendors (Adafruit, Amazon, etc.). The complexity level would be approachable to a typical digital maker.

A Tangible Illumination: The Trajan’s Weapon Frieze Installation (Tita Trajan)

We originally planned to develop the Trajan’s Weapons Frieze tangible interaction installation on the TITA table. Because of the specific requirements and limitations of the exhibition, this technology and design was not optimal for the project. The installation required that we ship the table internationally, requiring us to minimize the size and weight of the table and limit the potential for damage in transit; our table was a bit too fragile for as-is shipping, and would need to be disassembled, re-assembled and re-calibrated on-site, potentially performed by untrained museum staff. The location of our specific installation was in a non-climate-controlled space in the museum, which was also only partially secured from theft, with a planned exhibition duration of up to nine months; we were forced to consider the viability of long-term placement of sensitive computers and electronics. Lastly, the potential of up to several thousand visitors over that period made us consider the reliability and maintainability of the exhibition, considering such wear and tear. The museum has no dedicated technical support staff and would not be able to troubleshoot, calibrate, or fix the tangible table, should problems arise.

Consequently, we pursued re-designing the installation as a new portable table, using a “disposable” micro-computer (a $35 USD Raspberry Pi) and re-implementing the tracking/interactivity using extremely simple electronics and design. Placing a tangible piece would simply complete an electrical circuit by bridging electrical contacts via a metal piece on the back of the hand-held object, instead of accurately tracking the object (x/y) across the tabletop like TITA. The micro-computer would detect the event and trigger projected animated videos on the wall in front of the table. The design of the physical table would once again be completed via a digital process, and the subsequent fabrication of all components would be performed with a laser cutter and 3-D printer, using only easily-sourced and utilized building materials and electrical components, and assembled by hand as if a kit of parts, with glue and screws, and some hand sanding and painting.

Various activities showing the construction of the table an computer aided design. Figure 2: Tangible Illumination of Trajan’s Weapons Frieze (TITA Trajan): Vector cutting/etching drawing, fabrication/preparation photographs, completed table with tangible 3d printed piece (detail), completed table with projected display.

The basic table design was composed of multiple layers of ¼” baltic-birch plywood, cut in precise pieces, and glue-laminated together as a composite, the layering registered via laser-cut bolt holes. The inner plywood pieces of this “sandwich” included a cavity to accommodate the micro-computer, a power supply, wiring for the electrical contacts, and an HDMI cable. An inner, removable ¼” plywood panel, housed in the cavity, provide a mounting surface for the electronics and pre-cut slots to slip thru 1 x 1 x ¼” aluminum bar stock pieces which were glued into place. Input/output pins from the micro-computer were wired to these pieces, secured via screws fastened into pre-drilled holes in the bar stock. The top layer of the table was a single piece of ¼” acrylic, laser-cut to size, with holes for the tangible pieces and surface-etched with a speculative reconstruction drawing of the Weapons Frieze. The table was wrapped in 2″ x ¼” trim, framing the assembly and also accommodating a strip of LED lights, which edge-lit the acrylic layer and illuminated the table.

Six fragment pieces were 3-D printed in ABS plastic, from scaled 3-D models (.stl files) generated by the Duke Dig@Lab photogrammetry effort, scanned via the original artifacts. Each were modified with a flat bottom surface to accommodate and epoxy a 1″-piece of the aluminum bar stock. This metal piece was located so that when the tangible object was inserted into its corresponding puzzle slot, it bridged the gap between the two metal pieces located on the panel below, and completed the circuit. For security sake, each tangible piece was anchored to the table via a thin-gauge metal cable, screwed into the piece and the table.

For this exhibit, the table was set on a pedestal in a room, situated in the Trajan Forum exedrae. The HMDI cable from the micro-computer was routed to a bright 5k-lumen short-throw digital projector, housed in the pedestal, which projected the video onto an in-situ masonry ruin wall.

The total table fabrication cost, including materials and embedded electronics was less than $300 USD. This expense doesn’t include the cost of the digital projector, which could be sourced from existing equipment.

A photo of people looking at the completed table.

Figure 3: : Completed installation in-situ, animated infographic for typical fragment

Figure 4: A Tangible Illumination of Trajan’s Weapons Frieze (TITA Trajan)

The interactivity and animated graphics were controlled via a simple Python script running on the micro-computer. This script detected a tangible object being placed in its puzzle slot, which would then trigger the system to launch a video player that played the corresponding animation for that piece. The system would return to a base state video after a time, or queue a general curatorial video, if no activity had been detected at the table for a specified duration.

The TITA Trajan project focused on prioritizing technical simplicity and reliability, over providing a breadth of features and intensive interactivity or game-like mechanics. This desire was also motivated by understanding that the installation needed to create a complete experience in a short duration (1-2 minutes), to keep the queue moving in the exhibition. The majority of the development time, specific to the curatorial content, was focused on developing compelling and informative infographic animations (created in Adobe Illustrator and After Effects), and not intensive interaction design and software development.

A Simple, Inexpensive, Open-source Template for Future Tangible Projects (TITA-LITE)

As mentioned, the TITA Trajan project inspired an effort to abstract its strategies to a general project, TITA-Lite. TITA-lite provides set of instructions on how to build an extremely simple, tangible digital interface for an interactive video exhibition. The techniques and equipment utilized in this project are identical to the Trajan’s Weapons Frieze tangible installation, excepting the use of specialized materials like acrylic and the integrated LED lighting. The user can hold, touch, and examine physical pieces, and then insert them into the interface to start up videos related to each piece. The project requires the user to have access to a 3-D printer and laser cutter and to purchase the materials specified to complete the project in the step-by-step manner described.

The example project provided is generic—the pieces shown are simple geometric volumes, with corresponding descriptive videos with simple animations. These are placeholders; the same strategies and technologies can then be used to build another project with a specific theme, determined by the needs of the exhibition. The physical “tangible” pieces can be replaced with other artifacts, or 3-D printed from designed 3-D models. The related videos can be designed and produced, using whatever animation and video production skills the exhibition designer is comfortable with or selected from found videos to support the interaction and theme.

A screen showing a how-to sequence of illustrations

Figure 5: Simple Tangible Interface with video instructions

Figure 6: Completed project connected to external LCD display