In Darwin’s Garden : An Evolutionary Exploration of Augmented Reality in Practice

This chapter discusses the rapid developments in augmented reality and mixed reality technologies, from a practitioner’s perspective of making the augmented reality sculptural work In Darwin’s Garden . From its conception in 2012, to its exhibition at Carbon Meets Silicon II in 2017, the advances in augmented reality technology led to an interplay between the goal of the creators and the technological realisation of that vision. The art, design and technology involved, generated a reactive process that was mired in external inﬂuences as the accessibility to augmented reality became commercially valuable and subsequently restricted. This chapter will be of interest to anyone who wants to understand more about the possibilities, technologies and processes involved in realising mixed reality practice and about the commercial culture that supports it.

is a living link to the past, and through that connection there is a tangible nexus with the history of ideas, to science, and to the development of theories that have profoundly shaped our sense of what it is to be human [1].
The artwork comprises of two related works where the mulberry tree is central to the viewer's experience. In the first work, the three-dimensional structure and environment are digital; viewed on a screen or recently explored using a virtual reality headset. The second work is a physical sculptural form, with an augmented digital object at its centre.
The digital representation of the tree used in both works was formed from photographic imagery that included a year of time-lapse photography collected from four cameras placed in the garden of Down House. This body of time-lapse photography was the catalyst for the development of a digital 3D form. Chris Meigh-Andrews discussed how "3D visualisation seemed a natural extension and progression from previous work, and deeply related to the fact that the mulberry tree is itself a growing, living organic structure" [1].
The mulberry tree is now in decline and requires human intervention through the use of man-made structures to support the weaker branches ( Fig. 18.1). In Darwin's Garden uses full-size facsimiles of these structures in both forms of the artwork. In the augmented sculptural form, these create a physical space that the digital tree inhabits and the viewer engages with this physical space, exploring the digital form within it. The collaborative challenge was how to implement this augmented reality sculpture, combining both digital and physical elements in order to facilitate an immersive experience for the viewer.
The completely digital form of In Darwin's Garden is a three-dimensional structure set in an environment that can be viewed on a web browser, and more latterly this has been explored using a virtual reality headset. Within a web browser, this work is viewed as a window into a digital space, seen as another reality. The viewer can move around this digital space using a keyboard or mouse, but their physical reality is separated through the implicit knowledge that the artwork is a reality contained within the screen. In a virtual reality format, the viewer stands in front of the structure with the real world expunged from their sight. Virtual movement is by a handheld controller but the viewer's body does not move due to hardware and safety restrictions. The virtual reality experience is exactly that, a virtual reality that disappears when the headset is removed and the viewer returns to the real world.
These web and virtual reality (VR) implementations, while effective in their own right, do not offer what the use of augmented reality (AR) brings to the experience. Part intention, part necessity, the AR version of In Darwin's Garden brings an embodiment to viewing the artwork that is worthy of independent discussion. The technical journey to this augmented realisation is also of interest as the technology's rapid development posed interesting questions of remediation across realities. This chapter discusses AR and its use within a project that combined physical and digital structures, theoretical notions of digital and physical space and also details of the technical elements of AR for art practice. There is also the relationship between practitioner and technology and the evolution that occurs over time, as both evolve while developing the project; that is an important thread running through this chapter. My background is in industry and education, with a design practice that researches the understanding of digital space and notions of place, often working with computer animation and game engines. The approach to this collaboration was from the aspect of both designer and researcher into the possibilities of digital realities. The development of AR was, and still is, resolving the design and theoretical language needed to discuss its application. In 2011 Papagiannis likened AR to early cinema …in its infancy, when there were as yet no conventions. AR, like cinema when it first emerged, commenced with a focus on the technology with little consideration to content, marked as secondary [2].
The rapid and continued development of AR means it will take time before there are clear artistic conventions, for as Pearson states technologies are "not developed by the artistic community for artistic purposes but by science and industry to serve the pragmatic or utilitarian needs of society" [3]. This is reflected in the artistic development of In Darwin's Garden, which was at the mercy of commercially focused technological developments. But, as Malina states when discussing art forms enabled by the computer, "since contemporary culture is being driven by contemporary science and technology, one of the roles of the artist is as "coloniser" of the technology for artistic end" [4]. Chris Meigh-Andrews stated this was an extension to his previous work-it was definitely an extension to my knowledge of designing commercial applications for digital realities-so with the artistic vision discussed, we set out to explore the possibilities for an augmented sculpture.

Augmenting Reality
To augment reality is to blend another reality with a person's physical reality, so both realities are perceived as a single seamless environment. In the most common and current context the phrase "augmented reality" is thought of as blending digital imagery with the surrounding environment. It is often discussed as a technological development and not as a theory of blending a different reality with the real world. The most identifiable forms of augmented reality are looking at a mobile phone screen and seeing digital objects blended with the live camera feed, or more recently using smart glasses that directly overlay the digital elements onto the user's field of view. Yet the theoretical concept of augmented reality relates to more than a modern digital development and has a broader historical context in art and design practice. There are studies of artworks from Hellenistic times that superimpose painted realities onto interior walls, in a form designed to create the optical experience of both artwork and real world as a single reality [5]. The scientific development of perspective during the Renaissance led artists to the development of trompe l'oeil, mixing real and painted realities. Neither trompe l'oeil nor digital augmented realities require the viewer to lose their sense of reality; both blur the optical boundaries between what is real and what is not.
Renaissance theories of perspective are important discussions for the future of AR as the Albertian perspectival system that actualised trompe l'oeil is still driving the Cartesian logic of today's computer space and subsequent digital realities. McGuirk and Summers argue that augmented reality technologies bring "psychological and even philosophical concerns with regard to those [Renaissance] perspectival systems that underpin these technologies" [6]. And recommend the investigation of other forms of perspective for AR such as ocular, floating-point or multi-perspective forms that are less Western specific. Artists do not rely solely on Renaissance theories of perspective, so it may now be time for the artistic "colonisers" of AR technologies to explore other theories for developing practice and as Papagiannis discusses, not just remediate the current contexts and forms of AR but break out from the current environment AR is discussed in [2].

Extended Realities
The discussion of augmented reality in its digital form must be understood in the context of other digital realities as technology continues to drive this area forward and create new forms. A catch-all term used for this area is Extended Realities, commonly abbreviated to XR. It refers to all forms of combined real and virtual environments including augmented reality (AR), virtual reality (VR) and mixed reality (MR). If a spectrum is considered, where a real environment and a completely virtual environment are at opposite ends, then the range in between these two endpoints is where realities are mixed in different ratios. This is Milgram's Reality-Virtuality Continuum [7], a concept to aid in the creation of a taxonomy for mixed realities. The possibility is that this range may not be discrete but continuous and it has since been extended in another dimension using mediality. In order to be clear for this discussion, we shall briefly consider what defines virtual, augmented and mixed realities.
Virtual reality is a completely immersive reality that replaces the user's real-world environment with a simulated one. A headset covers the user's eyes, headphones cover their ears, then visual imagery and audio immerse the user in a digital environment. There may also be elements of haptic feedback to enhance the immersion.
Augmented reality, in its digital form, is where the real world is overlaid with computer-generated imagery with the intention to create the illusion of a single seamless environment. In order to avoid limiting AR to specific devices, Azuma [8] stated three characteristics for AR: 1. Combines real and virtual; 2. Interactive in real time; 3. Registered in three dimensions.
These were written before mobile phones became powerful enough to run AR technologies and so were prescient in their thinking.
Mixed reality is where virtual objects can interact with real-world objects in a form where the user can act on either, or both, with them having an appropriate reaction. A mixed reality headset uses sensors to map the real objects and track their movements within the field of view so digital objects can appear attached to real objects. The headset can recognise hand movements and the user can manipulate a digital object as if it were in the real world.
Extended realities will continue to develop and so definitions may be redefined by future technological advances.

The Drivers Behind the Development of Augmented Reality
Compute-driven augmented reality was first explored in 1968 by Sutherland [9] but remained a specialist area until the early 2000s when increases in processing power in affordable mobile devices enabled AR to become a viable technology with which to engage users. The development of a variety of AR software development kits (SDK's) for mobile devices meant developing AR applications became steadily more accessible to anyone who understood a certain level of coding. Companies released SDK's free to developers, but this meant the developer was locked into that company's technology [10]. An alternative to using an SDK is the use of augmented reality browsers. Developers register with the browser company and can then create AR experiences by uploading digital files to the company's cloud service. The browser will then download these files to a user's device. This business model locks both developer and user to the specific AR company and their browser technology.
The use of AR browser applications has enabled graphic designers to create printed material containing images that play video or show three-dimensional objects when the reader uses the specific browser on their phone. With this development's ease of use, an array of print-based AR advertising was created as a way of attracting attention to products and appealing to mobile user's curiosity to try AR experiences. The monetization of AR as an advertising format instigated the development of an array of applications and SDK's and the developers of mobile devices took note.
Metaio GmbH was an augmented reality development company that started in 2003 and was used in the initial prototypes for In Darwin's Garden. They provided an AR web browser and development kit for programming AR applications for computers, web and mobile devices. In May 2015, it was reported that Apple had bought the company [11] and Metaio announced all products and subscriptions were to be discontinued. Developers using Metaio had to find another way to serve augmented reality experiences to their users before the deadline of December 2015. In September 2017 Apple released iOS 11, their mobile operating system for iPhones and iPads, that included support for augmented reality development. Their application programming interface (API), called ARKit, allows third-party developers to build augmented reality applications that can take advantage of the device's functionality and processing power. The hardware developers of mobile devices were now directly supporting the development of augmented reality on their products through their operating systems.

Augmenting Art
In contrast to the evolving monetization of AR, artists recognised the opportunities for their practice. In October 2010 Sander Veenhof and Mark Skwarek created the WeARinMoMA exhibition in the Museum of Modern Art (MoMA), New York. This was not an official MoMA exhibition, but as the exhibition's website states an invasion showcasing the "radical new possibilities and implications Augmented Reality is bringing to the cultural and creative field" [12]. Using the Layar augmented reality browser application [13], an Internet connection and the global positioning system (GPS) on their phones, visitors were able to see digital objects inserted into MoMA's gallery spaces. Since then this form of unauthorised intervention has resulted in a range of dialogues between artists and exhibition spaces, exemplifying the conflict and opposition to traditional conventions both Pearson and Papagiannis discussed [2,3]. MoMA is still being used in this way with the 2018 MoMAR project targeting permanent displays in the museum for AR artwork interventions [14]. On the WeARinMoMA website, Veenhof and Skwarek added a cheeky "PS The MoMA is not involved yet" [12], and while MoMA has never responded they do now have at least one artwork in their collection that uses AR, Martine Syms, Incense Sweaters & Ice, 2017, [15].

In Darwin's Garden: Producing the Digital Environment
Production on In Darwin's Garden started with the web-based digital environment, as this was the less experimental production process. It was intended that digital elements from this web format could then be used in the creation of the second format, the augmented reality sculpture. Both artworks could be split into component parts of the tree and the supporting structure. The tree would be digital in both, but the supporting structure would be digital in the web format and physical in the AR format. The relationship between the component parts and their true to life scale to the viewer was deemed crucial to the experience.
…the old tree is now in its decline, with man-made structures supporting some of its branches. We would like to make full-size facsimiles of these structures to use as a foil to the virtual image of the tree and develop a work that would enable visitors to explore the tree in virtual space and time-Meigh-Andrews [1].
The viewer of either experience should encounter a full-size tree and supporting structure. This should not be a perfect digital representation of the tree in threedimensional space, as this would not carry the empathic connection of standing next to a living, dying tree. The viewer in this experience has to feel they are up close to a very specific mulberry tree, physically stepping around the framework supporting the old tree, getting close to the trunk and looking up through the canopy to the sky.
At the time production started there was experimental photo software, such as Photosynth [16], that could crowdsource photos of a landmark and then build a digital photo cloud simulation of the landmark from them. This approach was a precursor to photogrammetry, now used in the 3D scanning of real objects, where multiple photos are captured and the software extracts information from these to build an exact threedimensional representation. An exact replication was not the intention for In Darwin's Garden, but a representative photographic form where the viewer builds their own mental image of the real tree through the photo cloud approach offered interesting possibilities. This format also had links to David Hockney's two-dimensional photo collages-referred to by the artist as "joiners"-but in a three-dimensional form that would be at the actual scale of the subject matter.
Using 3D modelling software, the tree structure was assembled as a photo cloud comprising of single planar shapes with a photo applied to each. These photo planes were arranged in such a way as to create the abstracted form at the scale of the real tree. The physical framework supporting the tree was modelled so as to link with the tree in a manner representative of the real-world site. The time-lapse images were placed as clouds of photo planes around the structure in locations that were spatially representative of the camera locations ( Fig. 18.2).
The main technical consideration for this design approach was the quantity and quality of photographic images, more images equate to a larger file size and an increased download time. The photos included the time-lapse imagery meaning a single photo plane would contain 20 time-lapse photos, played in a looping sequence, and there were 20 photo planes for each of the four cameras. In 2012 the average speed in the UK was around 12.0 Mbit/s so the first version of the application at 86 Mb would take just over 1 min to download. This was considered to be too long.
To reduce file sizes, a consideration of how close a viewer will get to a single image was determined. It was expected that a viewer would be able to walk up to and into the lower areas of the tree structure. This meant that a single image in the lower section of the tree could fill the viewer's screen. Therefore, any image at this lower level must be the same resolution as the screen the viewer is using. A standard resolution, at that time, for playing a standalone application on a computer monitor was 1024 by 768 pixels.
Photo planes in the middle of the tree are at a height above the viewer's eye line so could be a lower resolution, as no single image will ever fill the viewer's screen. The photo planes at the top of the tree were bigger in scale, but fewer in number, in order to create areas of foliage and blue sky. These needed to be at the screen resolution as these would again fill the viewer's screen when looking upwards.
The author's previous design practice had explored the analysis of how trees move in the wind, applied to game environments, where wind and weather affected how a player interacts with an environment. Wind movement was explored for In Darwin's Garden using an algorithm to create a random direction and strength of the wind. Photo planes fluttered emulating foliage in the wind and added something to the presence of the tree structure, but it was considered too much of a simulation; ironically it did not feel natural in the digital environment. On testing it was left running over 24 hours, only to discover an issue in the wind algorithm meant that the photo planes moved imperceptibly over time. The whole tree structure would move across the space, effectively walking out of the environment. A key development point was to remember to leave each iteration running for a reasonable length of time, as it might in a gallery situation.
Experimenting with programming the photo planes to face the viewer meant that an element of movement was present but not overpowering. As the viewer moves, the photo planes overlap and intersect while rotating to face the viewer. This kept a sense of physicality and real-world movement within the abstracted foliage.
In its web-based form, In Darwin's Garden explores space and temporality surrounding the notion of place. The viewer can see Down House in the background locating them in the space of the garden. Within that space the tree's supportive frame is treated as a physical barrier the viewer must move around, while the photo planes of the tree offer no resistance to movement and the viewer can move through them. The photo planes containing the time-lapse imagery hold the location of the real time-lapse cameras making the viewer spatially aware of the image of the garden space and the real-world tree. This web version was finalised and uploaded to the IDG web site [17] and in August 2012 presented via Leonardo Electronic Almanac's digital media exhibition platform [18].

Production Process
At this point in production with digital assets assembled, the consideration of how to transfer the conceptual vision to an augmented reality experience began. Transmediation across forms of extended realities is not a direct process, as virtual reality offers complete immersion which brings greater levels of control over the viewer's experience than augmented reality, where the viewer can see their physical surroundings. The transmediation of In Darwin's Garden was not a simple transfer of digital assets; it meant overcoming technical issues while working with the dialogue between digital and physical forms, leading artist and designer on an explorative journey into the possibilities of augmented reality. Design enquiry alongside technical investigation is required for each of the component parts in an AR experience and this is a useful way to break down and reflect on the process. Those component parts are 1. Viewing Device: this runs the application and requires a screen and camera. 2. Augmented Reality Application: to be installed on the viewing device. 3. Digital Asset: to be displayed on the viewing device. 4. A Positioning Target: often an image but may also be a physical object or a GPS location that triggers and positions the display of the digital asset.
The principal for an AR application is that when launched it accesses the viewing device's camera, displaying the camera feed on the screen of the device. When the camera is pointed at a target image the application recognises this image and displays the digital object superimposed onto the camera feed. The digital object holds a fixed spatial relationship with the target image, so when the device is moved around the target image, the display shows the viewer to be moving around the digital object.

Viewing Device
The ability to position the work in any indoor or outdoor location was important for the development of In Darwin's Garden. In an indoor gallery, a viewing device can be supplied with a preinstalled application. Using a specific device means any application can be fully tested to ensure it works properly. Devices can be updated and interesting developments in technology, such as advances in augmented and mixed reality glasses, can be explored.
In an outdoor context, it is unlikely that a viewing device can be left securely at a site, so the viewing device has to be the mobile phone the viewer is carrying. The application will need to be developed for a range of devices and registered with the appropriate application stores. Downloading the application will be limited by the viewer's network transfer speeds and data allowance so its file size will be a factor in any viewing experience. If a person encounters the work outdoors and is not carrying a suitable device, the engagement with the sculpture will only be through its physical form.

Application Development
To use a pre-existing augmented reality browser would mean any viewer first has to download it from the Internet, then the digital object is downloaded while the browser is running. This is potentially the fastest development process and advantageously uses a proven and tested browser. But it brings in the extra stage for the viewer of dealing with the AR browser and its brand, which can act as a barrier to the process of engaging with the artwork. If an application is built specifically for the work it will contain all the information needed and is the only item to be downloaded. The disadvantage is that the application will need to be developed, tested and certified in order to be distributed by an application store. Also instructions on where and how to download any application must be visible near the installation. Augmented reality applications and SDK's for building applications are constantly being developed and improved upon but a useful starting point is A Comparative Analysis of Augmented Reality Frameworks Aimed at the Development of Educational Applications [19].
The decision was made to use the Metaio software tools to develop the augmented reality sculpture. This provided access to Junaio, a free mobile AR browser application for iOS and Android devices, along with software development kits for programming, PC, web and mobile augmented reality applications. The Metaio Cloud stored content online and the Metaio Creator software was a very good drag and drop creation system. Metaio also organised the insideAR conferences at the forefront of technological developments in this field. This suite of software gave flexibility in terms of choice of device, application development or a ready to use AR browser, and an offline or cloud-based approach. Metaio also supported the Epson Moverio BT-200 Smart Glasses that contain the processing power of a smartphone and the ability to superimpose the device screen upon the field of view of the user. These offered exciting possibilities for AR experiences so the development of the AR form of In Darwin's Garden began using Metaio tools, smart devices and Epson's Moverio glasses.

The Digital Object
There are various forms of digital object that can be displayed using AR; a twodimensional graphic in vector or raster form, a video file, or a three-dimensional digital object which may be static or animated. Images, text and video are twodimensional objects that can be mapped directly onto a target object to overlay it, or programmed to appear above it and always face the camera. A digital object might be "smart" meaning it can continually access device functionality, such as GPS location, to provide a constantly updated flow of information.
In 2013, AR advertising was starting to become more commonplace. AR was being used to play videos over car advertisements in magazines and to show digital replicas of the advertised car [20]. Three-dimensional objects can sit directly on or over the target object aligned to face a specific direction and also animated. A major factor in building digital objects to use in AR is file size. The larger the file size, the longer its download will be and the more likely the user will move on before the AR experience gets started. In the web version of In Darwin's Garden, the size of the digital asset for the tree was 36 Mb; this meant a minute or more download time over a 3G mobile network. To explore file size options different iterations of the digital asset were created by adapting the number of photo planes, the resolution of the photos and the number of time-lapse images in each animation. The augmented experience required a level of transmediation led by file sizes also considering a viewer's accessibility to an Internet connection, the viewing context in terms of location, and the active engagement with the augmented reality experience.
Firstly, the time lapse images were relocated to be in the tree structure amongst the images of foliage. A physical reason for this was the viewer might not be able to walk across a gallery in order to see the images as in the web version. Importantly they were now embedded in the experience of the tree, like fruit amongst the foliage. The viewer could recognise that some photo planes contain a sequence of landscape images as opposed to images of tree foliage. These became objects that draw the viewer into the digital space, so that they move in the real world around and through the physical framework. An interesting time-lapse image is where a portrait of the artist appears because Chris Meigh-Andrews was working on the camera as it took a photo, this creates the chance that a viewer will encounter the artist within the AR experience.
In the augmented experience, the backdrop photos of the house were removed because they show a fixed landscape behind the digital tree that is not there within the real-world context; this would break the viewer's immersion. Instead the view only holds the digital tree and behind it the viewer's actual location appears, situating this digital form in the real landscape with the support structure. This means other viewers can be seen as part of the view, situating them in both the digital and physical realities, and true to scale against the digital tree (Fig. 18.3).

Target and Positioning
The most basic problem that limits the immersiveness of an augmented reality experience is that of registering the digital asset correctly over the target [8]. Advances in the technology, needed to register a digital file in the correct position and hold it there, have made a huge impact on user immersion in extended realities. Early AR systems relied solely on images, known as fiducial markers, with the developer registering each target image to display an appropriate digital file. The markers placed in the environment were often black and white block patterns which could be distinguished in terms of direction to the camera and angle of view. These attributes could then be used to place the object on the target image with the correct spatial and perspectival relationship to the camera. Developments in image processing and camera resolution in mobile phones has meant that photographic images can now be used as targets, although contrast and asymmetry in a target image are important in order to calculate direction and angle of view.
Another positioning system used is the device's global positioning system (GPS). This is reliant on the efficiency and stability of the GPS signal and limitations occur for indoor locations where GPS information may be hard to determine. If GPS tracking is unstable then small changes in location can make the digital object appear to jump around in front of the viewer.
Metaio, then subsequently Apple's ARKit, can use an object as a target. This requires the AR application to know the shape of the object in order to calculate direction and angle of view. Developers create separate applications dedicated to scanning objects for use as a target.
Advances in environment recognition from camera feeds has resulted in the ability to position a digital file using markerless tracking. With this system, the application recognises the planar surface in the camera view and places the digital file onto this surface. This means there is no need to prepare an environment with markers as the digital file will locate itself and move around on any flat surface in front of the viewer.
The first iterations of In Darwin's Garden used the GPS tracking function within the Metaio software to align the digital tree form within the physical frame. Using the application outdoors, the digital structure jumped around due to issues of tracking and an inability to receive accurate location information. The sculpture is 5 m by 3.2 m and as the viewer walked around the sculpture, the GPS tracking was inconsistent. When the errors in tracking caused the digital tree to move only a few centimetres this was deemed acceptable, but when the digital tree would suddenly move a number of metres it immediately broke the immersion, as it appeared to jump outside of the physical structure. Further tests in a gallery space found that some devices might not be able to receive any GPS location information. After various tests, it was decided an image-based target was to be used as it was the most stable form of tracking.
An issue with positioning a large digital object is the tracking of that object when the viewing device moves off the tracking image. As the viewing device pans up the tree structure, the camera loses sight of the target marker and the digital structure would become unstable. This is also an issue where a digital object moves out of the field of view but the user will expect the digital object to still be there upon returning to view that part of the environment. This is commonly referred to as extended tracking and has been important in developing the possibilities for AR for dealing with more than a single digital asset in the user's environment.
During the development of In Darwin's Garden, Metaio developed object tracking and provided an application for scanning 3D objects. A problem was the large scale of the physical structure, as this technology was geared towards scanning small objects such as toys. Experiments with scanning a smaller maquette of the physical framework worked at the scale of the maquette but it was found that this could not be scaled up to match the size of the sculpture.
A development with the Metaio software was the ability to upload a digital model of the object that could be used for tracking a real object. This proved successful in recognising the large framework, but only if the whole framework could be seen within the camera view. If the viewer was too close to the physical frame, then the tracking could not recognise a component part in order to position the digital asset. If the viewer could be directed to approach the sculpture from a certain direction, where the camera would have a full view of the structure, then this was a viable method of tracking.
The experimentations in tracking eventually led to the use of a single image marker placed in the centre of the framework as this offered the most consistent stability during the developmental stages of production ( Fig. 18.4).

Exhibiting In Darwin's Garden
In 2015 a modular framework for the physical structure was constructed. Five steel units were fabricated to hold a wooden framework together that can support the two "A" frames that lean inwards as if they are supporting the real mulberry tree. The structure had been modelled in CAD, (Fig. 18.4), in order to create the necessary construction diagrams and this also meant an exact digital object file could be extracted to be used for tracking within the Metaio software.
In early November of 2015, the augmented reality sculpture was installed outside the Chester Contemporary Art Space for testing. The devices chosen to run the application where iPads and the Epson Moverio BT-200 Smart Glasses. Using a Metaio application, the iPads picked up the structures' shape and the digital tree form would hold within the structure with minor stability issues. Using the Epson Smart glasses, the lower resolution camera feed proved to be able to track the object but only in a good light. When marker-based tracking was used, the tree structure tracked with reasonable stability on both devices. Then in December 2015 Metaio revoked all licences for their software, as they had reportedly been bought by Apple in May of that year [11]. This stopped all applications from working and there was a certain irony that In Darwin's Garden, acting as a form of an archive for the dying mulberry tree, had itself become obsolete within 3 years of its conception.
There followed a period of 6 months of testing other SDK's and applications as commercial products competed to fill the gap in the market left by Metaio. The SDK from Vuforia was used to create a marker-based tracking system for In Darwin's Garden, but the possibilities of object tracking were not available. In September 2017, In Darwin's Garden was installed as part of the Carbon Meets Silicon 2 exhibition at the Oriel Sycharth Gallery, Wrexham. For this installation, the smart eye glasses were not used as these could not be secured at the site. Instead iPads were placed in specifically designed plywood holders that slot into charging stations. These holders were robust, having handles at both ends to allow two hands to hold the device (Fig. 18.5). They were designed to give confidence in handling the device and remove the fear of holding, or dropping, an expensive electronic device. This appeared to change the nature of the user interaction as users were more confident holding these larger objects. The users were quick to step into the physical space and interact with the digital elements and each other. The interconnection between the physicality of the real world and the nuances of the digital world appeared to be enhanced by giving the viewer confidence in their handling of the device required to engage with the digital reality.

Conclusions
Throughout the development of In Darwin's Garden, there has been the need to react to the advancements of augmented reality technology, as well as the disappearance of that technology when it became commercially valuable. This shifting dialogue between technology and artwork raises interesting questions of transmediation and archival. Do we keep developing an artwork until the technology facilitates the vision, or accept current technological limitations and compromise that vision? In Darwin's Garden is complete, yet for each new installation it is expected that the digital assets will need to be embedded in new devices because of software and hardware developments.
In its gallery iteration, it became apparent that there is an embodiment which occurs between the viewing device and user that facilitates a more complete interaction with In Darwin's Garden. This embodiment is inherent in the physicality of holding the plywood iPad holders with both hands and moving around and through the sculpture as these devices appear to push the digital foliage out of the way. This may be in part due to the true to life scale of the digital element that facilitates a tacit understanding within body movement and the path the viewer takes exploring the digital tree. This embodiment between user and viewing device may also be due to the connection we have with our personal smart devices. We are confident in positioning ourselves and our smart device in order to get the best photo. Subsequently, we have a familiarity with the spatial connection between a camera view and targeting objects of interest within it.
The smart glasses used in developing In Darwin's Garden were found to have a narrower field of view than human vision, meaning a frame appeared to clip the edges of the digital tree. This broke viewer immersion, as the frame appeared to float at a constant distance away from both viewer and object. As this technology develops to allow wider fields of view this disconnect should reduce, but in this instance these devices did not facilitate a truly immersive experience for the AR sculpture.
In the end it was the physicality of holding a framing device in a form where the user can twist and angle it with their body, hold it out or look in close, adapting the screen view to their preference, that was found to be the most intuitive form for the exploration of an augmented sculpture of this size. Personal smart devices can facilitate this intuitive exploration, so for external installations of In Darwin's Garden it will be important for viewers to download the application in order to engage with the experience using a familiar device.
In conclusion, there has been a constant tension between developing the augmented artwork, utilising technological advances and adapting to setbacks as access to technology was withdrawn. With each advance there was a temptation to be led by technology, but the transmediation of the vision, not the application of technology, was the essential driver throughout the development process.
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