HYPERMEDIA AND URBAN CULTURE: A PRESENTATION ON THE CD-ROM GEORGIAN CITIES
The technology of hypermedia presentation can be developed so as to highlight the new approaches of cultural geography, which emphasise the complexities of townscape perception. Hypermedia programs on urban history offer the options of relating maps and projects to views of built areas, or documents on social history to their cultural background, through interface elements such as windows, animations, interchangeable pictures, which structure the documents as embedded spaces, appearing as sets of options. This interactive presentation, which makes the unfolding of the program dependent on the user's choices, stresses the importance of the virtual as an essential constituent of the perception of cityscape.
Historical studies of urban culture in recent years have stressed the complexities of townscape perception, favouring an interdisciplinary approach in which semiotics, including rhetoric and image analysis, are applied to cultural geography, an approach indebted to the ›linguistic turn‹ now followed by the ›visual turn‹. The technology of hypermedia presentation can be developed so as to highlight this new conceptualisation. The epistemology of hypermedia has itself undergone an evolution in the past ten years, since the first theories defined programs by their governing ›metaphors‹ whereas the more recent ones were indebted to ›constructivism‹, stressing the user's role. The argument will primarily be based on the CD-ROM Georgian Cities (authored by the research centre Cultures Anglophones et Technologies de l'Information – CATI, Université Paris-Sorbonne – Paris IV), which was designed so as to demonstrate the potential of hypermedia for urban studies.
Present-day research on cities deals with the notion of urban space and spatiality; it applies the methods of spatial analysis to urban morphology and defines concepts of spatial structure. Recent studies have focused on the interaction between urban form and perception, such as the relation between grid patterns and the eye's search for unity, or between the design of places and phenomena of empathy; they have underlined the emergence of ›space deconstruction‹, dealing not with objects but with connections, not architecture (history) but geography.
The reciprocal relations between perceptions of the metropolis and the development of new media has frequently been studied, under the influence of thinkers of the earlier part of the previous century such as Georg Simmel or Walter Benjamin, especially in connection with the cinema's capacity to give a multiple vision corresponding to the experience of the modern city. This line of investigation can now be applied to the hyperspace of cities, and to hypermedia images of the city. Recent books have studied the relation between cyberscape and city space in the present day; ›virtual geography‹ emphasises the networks of cities and their ›transculture‹ combined with the sense of place. This approach can also be used to throw new light on present-day views of the past.
Recent developments in urban studies have been based on transdisciplinarity, not only in the diversity of the documents which usually belong to several disciplines, but also in an integration of the approaches, which allow the documents of social history to be contextualised and studied at different levels.
The hypermedia presentation can reflect this new approach, through hyperlinks which allow the user to contextualise each document: in the Georgian Cities CD-ROM, a section on Scottish music, including audio extracts, contains a view of an Edinburgh concert hall with hyperlinks to the section on the architect, and this page in turn leads to studies of architecture in society; literary texts containing references to the religious situation are linked to the sections on religious history; documents on social practices are associated with views of museums of daily Georgian life, which in turn can be replaced in the urban planning context.
The navigation paths allow for transdisciplinarity in the options they provide for changing from topographical to thematic approach: in a section on one city, following topographical logic, the user may find a topic (for example the use of a given architectural motif such as the Palladian bridge, or a practice of daily life such as tea-drinking), which will lead to a general section on architecture or on daily life based on thematic logic, which in turn, having analogues in other cities, will lead to a second section on another city, again based on topographical connections.
The relationship between the several possible approaches to a social phenomenon may also be exemplified in one screen concerning a single topic, thanks to the hypermedia function of giving alternative presentations of a document, each corresponding to a specific approach – for instance topography and history. The user may be given the choice of a topographical or historical version of a map of a city: a topic in urban history is the influence of political history on building, among others the development of the London estates by landed families such as the Russells or the Grosvenors, conferring on the characteristic Georgian squares and streets their names or those of related families; the topographical view of a London area can be given historical depth by adding such explanations, and this dual view can be modelled by superimposing a genealogical table on a map of the Bedford district, enabling the user to add the historical approach to the geographical one.
The recent approaches in the spatial analysis of urban morphology, which concern the perception of space, can be not only described but visually modelled through hypermedia functions, which can be adapted to past perceptions of space as reconstructed by cultural history.
Studies of urban culture have analysed the experience of space and place; they have stressed the differentiated geographies and relationships between spaces, the combinations of layered or fragmented spaces and homogeneous integration through a rational grid. Cultural geography has made much in recent years of the tension between ›space‹ and ›place‹, the general view of space and the sense of the individuality of each place. The various perceptions of the urban environment in the different cities can be made evident through distinct hypermedia treatments. Multimedia functions can illustrate this on the topographic level: maps of cities can be overprinted with plans showing the geometrical construction, in cases like Edinburgh where the New Town was built according to a masterplan; since the development of Edinburgh is based on the contrast between the Old and the New Town, the animation mode showing the appearance of the New Town after that of the Old Town may be selected. On the other hand, in cities like Bath where the master-plans concerned certain architectural motifs like the Crescent (belonging to architecture rather than town-planning), the geometrical underlining will be applied to the map on a different scale: instead of the overall contrast between two parts of the city, the development of Bath focused on a series of planning motifs – the Circus, the Crescent; the sense of urban space is thus that of a series of detached smaller spaces each with a perfect unity. For the map of Bath the hypermedia function chosen was that of the thumbnail, which makes a view of a part of the city appear when the user rolls over it; the option of making elements appear at the click of a button will stress the dual level of reading of the townscape, which depends on the user's choice. London is even more of a series of different places, and the relationship between each of these fragmented London districts had to be shown as a difference in scale; the combination between the unified overall view of a town and the multiplicity of smaller spaces included in it can be exemplified for London through alternations between general maps and section maps; they alternate through a ›zooming in/zooming out‹ function; besides when zooming out from a section map (for example the Whitehall section, the St Paul's section) to the main map of London, the position of the current section is highlighted by a coloured patch, relating the part to the whole – the position of the coloured patch obviously changing when zooming out from a different section.
Technically this is a »field« option: it is made possible through the option of changing the background colour of each part of the general map separately, at the command of a script in each of the corresponding section maps considered as a ›field‹ text. A similar effect is used for the »site map«, a table of contents which is always accessible, and in which the title of the current section from which the user is coming is highlighted. The highlighting capability, which identifies parts in a whole, show the reciprocity of text functions and image functions in structuring documents; in the present case a field ›text‹ function is used to highlight topographical places, but conversely texts can be structured using ›image‹ functions, since the colours of hyperlinks can be obtained by choosing the appropriate ›ink‹ (transparency effect) for rectangles placed on them. The ›text/image‹ tools of analysis are thus projected onto the spaces of cultural history.
b) Places and their significance
These approaches have worked by using important places as starting points and interpreting their significance – the streets, the register office, the pleasure gardens, the prison – which implies a theory of the ›production‹ and ›construction‹ of significant spaces in the public imagination of the period, in which the physical appearance reflected a social interpretation which in turn it propagated. Cities are thus interpreted as combinations of writings and images seen as »signs«. The multimedia approach, which can structure space as »space syntax« can show the various levels at which a given urban environment took significance and became a social landmark, by articulating an image of daily life, a comment, and a thematic generalisation. For instance a view of Covent Garden can branch out both to cultural life (the theatre), economic life (the market), and to its reflections in literature (Smollett) and in the arts (Samuel Scott, Hogarth, Malton, with a pictorial analysis showing how representations of these places were constructed, and how the view could be transformed according to the viewpoint selected). The current interest in representations of cities in the public imagination can be explored through hypermedia, since various time-based techniques, such as animations and transition effects, can be used to reflect the relationship between cityscapes and their textual accounts (Smollett, Defoe), or their visual images (perspective diagrams showing the relation between designer's visual practices and the perception of the urban environment).
Since such approaches have stressed the representations of urban spaces, they imply analysing the viewer's position and integrating it into the study; they frequently depend on ›viewpoint‹ studies. Their key concepts are »visuality«, the linking of »spatial metaphors and speaking positions«, or »spaces of knowledge«, the »siting of the viewer«; they consider »geography as situated knowledge«, or »models of the self« and »reflexivity«, the study of images »of –« and images »for –«. Hypermedia functions, which include role-playing effects simulating the viewpoints of period characters, can help the users to visualize the difference between their own viewpoint and that of the characters.
Such approaches imply concentrating on ›visions‹ of the city, with the possibility that several viewers or social groups have different versions. The theory of mediation supposes that messages encode structures which mediate representation.
a) Mediating viewpoints: modes of representation
Historians of culture have studied the perceptions and representations of places, the places which structured the ›gazes‹ in paradigmatic ways, the optical devices which modelled these ways of looking, especially optical toys, »machines for vision that created ways of looking«, and the interaction between the construction of these objects of vision and that of personae for the viewing subjects themselves.
Such correlations between changes in the viewers' position and changes in the objects viewed may be modelled by hypermedia functions. The option of substituting series of pictures allows the user to experience several views of a townscape from the various viewpoints of several characters, or of one character shifting his ground: the object changes as the subject changes.
These variations can extend to modes of visual experience. The pleasure garden Vauxhall has been seen as a place where the visitors' visual experience would superimpose the »gaze« (an overall view) and the »glance«, the serpentine meandering perception. Hypermedia functions can model this diversity, and the workings of these devices, especially through animations enabling the users to cast themselves in the role of eighteenth-century viewers and to share their vision. In the Georgian Cities CD-ROM, the section on Vauxhall first contains a map (the gaze) then frames with zooms and changing views accompanied by a Vauxhall song emphasising the duration of perception (the glance).
b) Hypermedia and metaperception
The study of visual culture in urban culture has focused on the history of optical instruments which were used in each period to visualise the world; researchers have thrown into light the Renaissance use of the camera obscura as an image of the workings of the eye conjuring up the viewer's image of reality, and perspective techniques in the classical age have been studied in connection with the political order, since they would among other things govern the representation of a space ordered in accordance with the king's viewpoint, the rise of the panorama has been studied in connection with the growing image of the metropolis from an isolated point of view, the projection of the self, a new version of the flaneur. These optical models were conceived in accordance with prevailing viewing practices, while at the same time developing new modes of vision in »avant-garde struggles to reinvent vision« in the »belief that particular techniques are liberatory«. An analogy was thus established between optical tools and the modes of vision of social space in a given period, emphasising the interaction of form and content in these media.
Optical instruments have been studied in texts and engravings, and reproduced in cardboard working models which allow the user to simulate their actual use. Hypermedia presentation can now model their working. So that instead of writing about classical scientists' use of the camera obscura as a model for the process of vision, or of perspective as a means of ordering space, we may use a CAO program to model the actual use of the camera obscura or of perspective construction, showing each step in an animation, or allowing the user to superimpose perspective diagrams at the click of a button. The CAO programs have been conceived as extensions of the pre-existing conventions of technical draughtsmanship (›perspective/parallel‹ projection). Cityscapes can be animated, or they can bear superimposed diagrams to show their perspective grid, so as to reproduce the Georgian perception of them.
The new information technologies throw into focus the mediation of thought by machines, and therefore, by analogy, they retrospectively make us reflect on this mediation process in the traditional media. They cause a critical awareness not only of the relation between medium and message in past media, but also, as a consequence, in present-day media, including themselves, which they historicise. They are a tool of ›metaperception‹.
These historical modes of vision may have varied according to people's professional ways of looking, and we have the geographer's view of the city, the engineer's approach, the painter's vision. These various views of the city, and the tools mediating them, can be materialised not only sharing the public's view of them, but also that of their constructors. Animation and interactivity model the use of tools from the user's viewpoint: this time it is the simulation of a process from the technician's angle.
a) The simulation of design techniques
Hypermedia functions (in particular interactivity) can be used to allow the user to simulate eighteenth-century techniques in cartography or townscape painting. To simulate drawing techniques, we can use hypermedia as an animation modelling the steps actually taken by the draughtsman, or as a series of options enabling the users to try out for themselves the various possible perspective constructions.
Some of these modelling techniques apply to modes and techniques of vision. One of them is the panorama, the late eighteenth-century circular rooms with a townscape painted on the inner walls so that the viewer has the impression of being surrounded by a city. This new panoramic perception of the metropolis may be modelled in an animation in which the users see views of the city passing by as if they were turning on themselves in a panorama. The users of a hypermedia program may also practice perspective rendering and view ›prospects‹ with a Georgian draughtsman's eye.
Hypermedia programs may also model classification techniques, supposing views of humanity as calculating selves and spaces in an ›information society‹, as engineers of space practising long distance control, they may model time-space compression (time-tables), basing spatial metaphors on technology. Hypermedia programs can simulate the techniques of production of such tools of knowledge, for example map-making, through editable fields in which the user can do mathematical problems: the user may see how maps started being done with trigonometric techniques by filling in tables of measurements and seeing the resulting map. In those cases, it is the practice of a technique and the acquired skills which model a worldview.
b) The cartographic metaphor: space and text
Much has been made of the relationship between maps and texts, the idea of »writing cities«; with the emergence of the notion of »textscapes« this approach has usually evolved in conjunction with hypermedia presentation.
Recent theories of the map as spatialisation of knowledge architectures have taken geotemporal cartography as a model of an ›unfoldable‹ perception which contains past and future, of a dialectical relationship between mobility and a data-driven model or grid. The cartographic metaphor can be used in symmetrical ways: starting from the map, cartography may be seen as an intellectual model, in postmodern geographies. On the other hand, in theories of semantic representation and of the ›blending‹ of concepts, mapping may be seen as a metaphor applied to other fields of knowledge and creating a mental map. Hypermedia can model this reciprocity: texts referring to urban spaces may be spatialised and transposed on maps, or vice versa a map may be a starting point leading to related texts. For Smollett's Humphry Clinker, the first option was chosen, with the text appearing first and places mentioned in it being hyperlinks. For Defoe, the reverse option was selected, sentences from the text appearing close to the map. This is a way of suggesting the difference between the synthetic structure of Smollett's text and the spatialised nature of Defoe's writing. Anyway the map structure, because of its multidimensional layout, suggests the options of multiple navigation paths.
Moreover, maps may be meant both for knowledge and for action. GIS may be linked to cognitive processes based on ›if‹ questions, contextualisation and motivation (›fly-through‹), the double encoding of multidimensional data. The user of a map may assume two roles: it may be a map for study, with the user being extrinsic to it, cast in the role of a geographer seeking data. In this case the corresponding hypermedia function will be that of the GIS, with database extraction of statistics according to spatial criteria. It may also be used by travellers, themselves included in the space represented by the map, to select a route. This will again be modelled in hypermedia by having a surrogate character in the program moving on a map in such ways that the user sees the landscapes viewed.
The map combines space and mental organisation; it implies classification and the possibility of reordering data, a detail becoming the main focus. Figurative mapping in hypermedia implies a question-and-answer relationship between details and their intellectual environment; it also models the choice between options, ›mapping choices‹. It therefore constructs the viewing subject in several roles, sometimes as an external ›informant‹, sometimes as an ›actor-observer‹ included in the narrative.
Because of their multimodality, hypermedia functions raise questions on the levels of interpretation of signs.
Elements on the screen can play multiple functions, serving as interface elements, signs become signals; multimodality is thus combined with multifunctionality.
The interface elements offer a set of visual cues modelling the relations between elements of the urban space.
a) Windows, thumbnails, pictures with hot spots
Such interface elements give the options of showing the relationship between the part and whole, or the different scales, in an urban environment. The eighteenth-century urban space combined the unified designs of the New Town of Edinburgh, of the Royal Crescent in Bath, of the London squares, with the interconnected and sometimes contradictory layout of the streets, rooms and furniture: both the hierarchy and the tensions between these different scales can be mediated in electronic presentation, with functions such as the zoom or the alternation between images relating (for instance) plans and reality, and the use of virtual reality reconstructions, such as those of the Alberti Group and CASA: the development of Bath, Georgian Edinburgh, Soane's Bank of England.
The conceptualization of the Georgian urban world can thus be modelled through the information space of hypermedia presentation, which becomes an epistemological paradigm. It allows the backtracking of alternatives, of explanations which were being constructed.
b) Frames within frames, blown up images
Various hypermedia functions may be used to modify one element in the frame while others remain identical. The relative proportion of constant elements to changing elements in a sequence of frames is significant. The most frequent case is to have the general background of a frame remaining constant over several frames, and a detail changing from frame to frame: the user may select to try different lighting effects on a part of a townscape (a function adapted from CAD software), thus simulating the painter's range of choices. This effect of gradual and continuous change is effected through the script which, when the mouse button remains pressed, replaces a ›cast member‹ by the next one in a series (here: the views of a part of a landscape, each with a different lighting in sequence from sunrise to sunset). But a contrary effect may be to have one small element remaining constant and reintegrated into a succession of distinct backgrounds: a view of a dome being surrounded either by London (where it becomes St Paul's) or by Venice (when it becomes la Salute) shows the superimposed inspiration of painters, thanks to the device of the looping animation.
Several modes of hypermedia allow for the presentation of choices. Geography has focused on topics such as the role of »virtual« perception in the image of the social environment or of »simulacra«, and the way in which they can be »thought and written« or »embedded« in reality. They cast the user into the role of a character presented with choices as in life. Though interactivity is the most frequent presentational mode, animation can relate mutually exclusive options as well as it can show their possible superimposition. It can relate syntactic and paradigmatic approaches; though at first sight animation is syntactic and interactivity paradigmatic, they may superimpose or exchange their roles.
a) Animation or interactivity?
Animation usually represents a process, and interactivity represents choice, but there are variations. Though displaying series of objects or persons (for example similar trades) would seem to be demand interactive presentation (choice on a list), animation can be used also for series (engravings of different categories of peddlers), accompanied with music as each item unfolds: this suggests an evocative reconstruction of society, with the literary successive structure of the song.
Interactivity may be used to allow the users to select alternative options: the ›perspective‹ effect enables them to give several degrees of distortion to objects, trying out pictorial effects and finding how painters may have combined several perspective projections in one painting – for example in the Zoffany ›water music‹ scene, a strong foreshortening for the musical instruments as opposed with a quasi inexistent perspective effect for the figures (strong distortion being against etiquette for figures).
An animation can also be used to analyse paintings. It can show not only a process but also the superimposition of two pictures, two options combined in one by alternating. It is well known that painters gave composite visions of cities, combining several views from slightly distinct viewpoints implying lateral displacement so as to insert more elements of the cityscape which would never be visible simultaneously, their skill consisting in giving a seamless appearance to what is actually a composite picture. This can be deconstructed and explored by showing each of the actual views of the city as successive frames in an animation, which partly combine in the viewer's eye as they would in the painter's vision, while underlining the difference between the contradictory pictures of which the painting is made.
Hypermedia functions also offer the possibility of showing a series of options through »lists«. The changing elements may place the user in a position of having to choose: a list may be given, and distinct windows may be opened according to the user's choice, this time cast in the role of a character – or an observer. Lingo code (part of the programming section invisible to the viewer) can take the form of tables of columns associating a list of words with a corresponding lists of images, or vice versa, in which scripts command that when clicking on an item in the first column, the corresponding item of the same row in the second column will appear, by substitution for the previous element corresponding to the item of the first list clicked previously. For instance a list of the times of the day can, when clicking on each item, cause the ›event‹ of having a view of different activities appear in a window, each being appropriate to an hour of the day.
The reverse effect (the user clicking different pictures and the corresponding text appearing) is possible through »fields« (editable texts): architectural diagrams can be associated with a text window where the technical term for each architectural element on which the user clicks appears. Some of the hypermedia elements, called »field« texts, can be edited by the user: the user can write in a box and obtain a result differing according to the answer. The text may be made of figures, on which calculations may be effected. The engineer's view of the city may thus be simulated, for instance the user may select some of the measurements for a new bridge (for example the length) and use this function to calculate the change of level – a script having prepared the multiplication function.
d) Conditional scripts
Programming languages allow for conditional scripts, of the type »if the user clicks on the first button on the map, go to the screen on [...], if the user clicks on the second button on the map, go to the screen on [...]«. This allows for the expression of modality, and of the relationship between the real and the unreal, in tense and mood, of negation, or of the past.
e) Interchangeable objects
Among the events caused by such conditional scripts is the replacement of objects, one picture being substituted by another upon a command. This may be combined with lists, each item in the list being linked to a script commanding the replacement of the preceding picture by a new one. These effects, associating a list of phrases with corresponding pictures, may be used for the study of social codes, such as the »language of the fan«: when the user clicks on any of the phrases which a lady of fashion might have wished to mean, such as »do not forget me«, a vignette of a woman holding a fan in the coded position replaces the empty frame.
Such conditional scripts enable the option of having an ›invisible‹ element in a picture become ›visible‹ at the click of a button and superimpose itself on the existing ones. This allows for several ›layers‹ of reality and their interpretation to be represented: a manuscript and its transcription, a word and its explanation, corresponding to different approaches: the text and the paleographer's interpretation, the text and the lexicographer's interpretation.
Choosing which element appears first, and which one is invisible and appears only at the click of a button, corresponds to the choice of an approach, and therefore casts the user into different roles. An architectural view with a comment may be overwritten with an architectural diagram. This effect may be used to trace the various steps of a process in contrary ways: if the view appears first, and the diagram if the user clicks, it reproduces the visitors' experience, first seeing the view and then interpreting it. But the effect may be inverted: the diagram may appear first, and if the user clicks, the building will be superimposed on it; this is the architect's approach, following the steps from design to reality. These inverted effects may be used to suggest the various possible ways of viewing the city, and how they are framed by a professional approach.
These options can apply to sound effects: the users may have the option of listening to a musical piece played either on the harpsichord or on the spinet, in which case they may cast themselves in the role of a composer selecting the instrumentation of a piece, or of an amateur listening to two concerts.
Programming languages allow for two types of effect with the mouse, one being »rollover« and the other »click«, which correspond to different forms of modality. Invisible elements can become visible if the user simply rolls over a hot spot, for example when rolling over a map, showing thumbnails of buildings on the various places where the mouse is passing. So far this means showing the options, we remain in the optional mode, revealing the possible buildings which might be explored, and the user can make all these possibilities appear while remaining on the map. But clicking on one of them will take the user to the screen on the building selected: this is moving from option to reality. The hypermedia functions can reflect the relations between the virtual and the actual in the imaginary view of cities.
h) Spaces: intersections, horizontal and vertical locations
The perception of places implied, not only describing the individual features of each place, but also their modes of interconnection. Novels narrating the journey of a character within a city usually emphasise the distinct urban milieus through which the character's itinerary makes a link, for instance Moll Flanders making her way through London streets till she reaches the prison. A hypermedia function may throw into relief the succession of places through which a moving character passes; on a map, visual events may be caused successively in each of the zones through which a figure passes, thanks to the »intersect« script: invisible patches may be placed on the map, corresponding to each of the separate significant areas of the city, with a figure representing the character being made ›moveable‹ (dragged by the user), and a script programming an event every time the moving character ›intersects‹ one of the areas, for instance the appearance of the text of the novel referring to it.
The perception of urban space was also structured by architectural practices, and the classical building codes which visually subdivided buildings into recognizable motifs and parts combined according to prescribed arrangements, such as those governing the use of the different orders of columns. The perception of a building thus implied an overall view of its whole height on one scale, and also focusing on each of the sections, that is the storey with Doric capitals, the next storey with Ionic capitals. To render this mode of architectural vision on two different scales, a hypermedia presentation may show a vignette of the whole height of the building, while allowing the users to view a close-up of a section at any level they choose. This was done for the Circus in Bath, which has three storeys each with an order. The functions used were that of scripts modifying the horizontal and vertical positions of a picture (the code expression being »set the hloc of [...]« – »hloc« meaning horizontal location), and the command modifying it being the position of the mouse: when the user clicks on a given level of the view of the Circus in the vignette, the program calculates the present position of the mouse and accordingly modifies the vertical and horizontal positions of a large scale view of the house so as to make the corresponding detail appear in close-up in the window.
In addition to the ›handlers‹ and the commands, the author of the program may thus create ›variables‹ – in the present case, a variable corresponding to the changing position of the images, on which the user can act, provoking events dependent on the variable (changing close-ups of architectural details); this suggests a view of the cityscape structured by sets of related concepts and mathematical equations.
The changes in the objects imply different constructions of the subject – as viewer, as character –, the latter one being cast in the role of a visitor or of a professional.
a) Buttons as signs
For buttons and hyperlinks, or thumbnails leading to a zoom, the analogical relations, the ›sign/meaning‹ relations, are pragmatic since they are linked to the viewer's action. Meaning is doing, in a performative manner. On each screen, some elements have an interpretative relation to the present screen (legends of a picture) but others (buttons) refer to the next stage and point to a yet invisible element: they imply movement; signs are signals. Elements can be metaphors of the whole, but each screen is a synecdoche of a whole which keeps reordering itself as an implicit background map.
b) Interface effects
The structural function of navigation buttons may be superimposed with that of objects in the cityscape represented. The significance of objects in material culture may be brought out by making them into interface elements which set forward the navigation in a way consistent with their use in reality: a clock may serve as a button to turn to the next chronological section, an opening arch may serve as a menu for a section on architecture. These icons may thus evoke the inversion created by passages and arcades between indoors and outdoors, between the space of the enclosed object or the surrounding space of architecture.
When such interface elements for the introductory screens of chapters are adaptations of the picture frame, or of the architectural arch, it is their structural function which plays on two levels, that of the content and that of the medium.
The texture of the interface effects itself reflects modes of vision. The range of transition effects provided by multimedia authoring software may be used in sections on pictorial views of the city to suggest the broadening of field of vision in the spatial perception of the period (»centre out square«) or the direction do the gaze (»cover up diagonal«). They may also be used in sections dealing with literary descriptions of cities, as equivalents of literary narrative viewpoint effects: »random columns« will suggest a change of viewpoint in the text; »zooming in« will suggest a change in the focusing of the descriptive technique. Transitions throw into relief the coloured surface itself through »pixelisation« (causing the pixels constituting the picture to appear individually); pixelisation foregrounds the texture of the picture, so as to underline a structural transition.
These combinations of functional structure and model structure in the representation of cityscape imply multiple roles for the viewing subject; besides, the ranges of options given by hypermedia authoring transform paradigmatic alternatives into sequential events, or vice versa interpret sequences as experiments in alternative solutions. This emphasises the importance of the virtual as an essential constituent of reality in the perception of cityscape.
Prof. Dr. Marie-Madeleine Martinet
Centre Cultures Anglophones et Technologies de l'Information CATI
Université Paris-Sorbonne - Paris IV
1 rue Victor Cousin
F-75230 Paris cedex 05