While discussion so far has focused on the technical implementation that led to the animated outcome, the remainder of this article will look at how the narrative theme was realised and the project's objectives tackled by a process of creative decision-making.
Using limited reconstructed elements, the interpretation of the archaeological narrative was conveyed in part by using the camera, lighting and weather. A reflection will be made on the attempt to incorporate these photographic and cinematic considerations into a visual toolkit for storytelling. The second part of this discussion will consider how well suited the low altitude aerial perspective was to the project's objectives.
The animated outcome aimed to reflect the experiential values of visiting the site as far as possible. For this reason it was appropriate for lighting and weather conditions to play an active part in the narrative. The breadth of these conditions was based on the experience of conducting fieldwork at Jarlshof in all weathers. The changeable nature of the weather conditions in the Shetland Islands afforded an opportunity to incorporate weather as another storytelling element without departing from fidelity to the site itself or the narrative theme.
The weather conditions in the animated outcome were derived from a combination of simulation and gathered imagery. Fog was artificially added to the Late Iron Age phases to enhance both atmosphere and sense of scale around the setting of the broch and wheelhouse reconstructions. Snow was introduced during the Norse settlement using a combination of dynamically simulated snowfall (produced in collaboration with Thomas Hogben) and photographs of lying snow on the site and at Boddam Croft Museum, Shetland Mainland. This change of weather was designed to reinforce the narrative by reflecting both the radical change in architectural style brought by the arrival of Norse culture, as well as the northern climate of the settler's origins.
By remaining close to the gathered imagery it is hoped that 'Jarlshof' can be better associated with the experience of visiting the site. This approach extended to the reconstructed elements, which were as far as possible derived from photographic imagery. While the resulting aesthetic aims to be both immersive and evocative, there are inherent dangers in the use of photographic detail in such a speculative portrayal of lost structures. The combination of aerial photography and computer-generated imagery used in 'Jarlshof' results in a highly technical image. Eiteljorg (2000) describes how the combination of engaging detail, and the perception of the computer image as belonging to a 'rational' process, lends a certain authority to such outcomes. In response, many have highlighted the need to offset this perceived authority by visually separating conjuncture from evidence in computer visualisation. This has been approached in a number of ways, such as by including alternative versions of speculative elements (Giles et al. 2012), delineating different levels of certainty in reconstructions (Eiteljorg 2000), or providing visual cues where there is uncertainty (Zuk et al. 2005).
Including alternative versions of the reconstruction fell outside of the scope of the 'Jarlshof' project. As such, it was particularly important to suggest the speculative and artificial nature of the reconstructed elements while blending them into the surviving remains. Having the reconstructed structures slowly fade in and out of the scene was considered an appropriate way to do this, as the dissolve effect implied that the imagery had been manipulated.
While Zuk et al. (2005) suggest varied transparency as one suitable way to demonstrate temporal uncertainty, the effect was used differently in 'Jarlshof', where each phase represents a speculative fixed point in time annotated with an approximate date. This simplified version of the site's chronology was selected to help the visitor to grasp the overall story of the site, along with a suggestion of the phasing and changes in architecture. The speculative nature of the reconstructed elements was reiterated in a text caption at the end of the film, which also details the other sites that were used to inform the reconstruction. It was hoped that acknowledging the methods of production in this way, and using the dissolve effect for the reconstructed elements, might suggest to the viewer the artificial nature of the imagery. A thorough evaluation of how an audience responds to the authority of the outcome is an area that deserves further study.
The aerial view presented by the animated output serves to reveal the structure of the site, parts of which are difficult to grasp from ground level. As a format, however, the elevated camera would seem at odds with the stated objective of relating to the visitor's experience. Gillings (2005, 227) describes the convention of the fly-through as 'the digital equivalent of a flying carpet', suggesting that it goes against the 'accuracy' that archaeological models strive to achieve.
Beyond this, the aerial gaze has been affiliated with the cartographic tendency to project 'authority and power' (Cosgrove and Fox 2010, 8), and its limitations as a way of representing archaeological landscapes have been recognised (Thomas 1993, 25-7). Yet since its beginnings, aerial photography has challenged the observer's relationship with landscape in unexpected ways (Saint-Amour 2003, 363; Cosgrove 2008, 89). Fox (2009, 100) suggests that the aerial view is actually a 'normative' way of looking, which draws upon natural cognitive processes. The oblique low altitude aerial perspective used in 'Jarlshof' was intended as a compromise between the relatable ground-level view and the revealing yet distancing qualities available from high altitude.
The 'flattening' characteristics of the air view have long been recognised (e.g. Piper 1937, 7) and the need to re-introduce depth cues to show up relief has been addressed by aerial archaeologists in a number of ways (Hauser 2007, 163; Verhoeven 2011, 67). The low altitude aerial perspective allows the use of wider-angle lenses, which can aid depth perception in part by increasing the effect of foreshortening. The computer-generated cameras in the 'Jarlshof' animation used a wide field of view to emulate this effect.
Camera movement also served to enhance the viewer's perception of depth and the three-dimensional structure of the site. Slow tracking shots were used to maximise visible parallax. This format bears no resemblance to the normal experience of moving around Jarlshof. It was hoped, however, that the depth perception afforded by this flying motion would enhance the viewer's sense of the site as a three-dimensional space that can be explored. The camera was also used to create a sense of progression through the distinct chronological phases of the site. For example, the Norse settlement is approached from above the Iron Age wheelhouses, a point where the chronological change in architecture is clearly visible. While this would not have been as viable at sites with more complex sequences of truncated structures, the excavated portions of Jarlshof happen to be distributed in such a way as to allow a chronologically coherent path around the site.