Glossar-English:Interactive Images

Sub-item to: Bildverwendungstypen

Original: Interaktives Bild

---

Image presentation in interactive systems Like moving images (⊳ Film), interactive images are a very specific type of image with characteristic use conditions. An interactive road map, for example, is the pictorial output of a computer system that can be used to present a road map; in addition, the expression ‘interactive’ also promises that the map shown and its presentation can be influenced by the user in a non-trivial way, for instance by zooming, moving the section shown, enlarging or reducing the size of the labeling, omitting or adding railroad lines, rivers or sights, searching for an address and highlighting the result on the map, calculating and displaying a route, etc. Similarly, we expect an interactive anatomy atlas, like a traditional paper anatomy atlas, to contain anatomical drawings that can be shown to another person – or to oneself in the role of another person. In addition, however, the interactive version should also allow the user to manipulate the drawings in a manner that goes far beyond the capabilities of a book. Strictly speaking, interactive images are a complexly organized set of images from which selected image sequences are automatically presented to an image user by an interactive system – usually a computer system – in such a way that the system reacts to the user's activities in real-time – i.e., without any noticeable delay. Therefore, they are digital media. The images of the set do not have to be available in advance as an image carrier (or in a syntactic notation such as jpg), but can be generated as required by means of computational visualistics. For this reason, the set on which the interactive image is based can also (theoretically) be infinitely large. Formally, the interactive image is the set of possible image sequences the interactive system under consideration can generate with the permitted user input. The concept of interactive images is closely related to other interactive media, such as those exemplified by the so-called natural language systems of “artificial intelligence” (AI). Instead of sequences of images from a set, sequences of verbal utterances from a given set are presented depending on the current user input. Figure 1: Still image of the oscilloscope screen from «Tennis For Two» As the existence of interactive images depends on computer systems and corresponding input and output devices, they have only appeared historically since around the mid-1950s. Oscilloscope displays that depend on user activity can be regarded as early forms. The «Tennis For Two» system developed by William Higinbotham in 1959, which used two rotary and two switching knobs for input and a simple laboratory oscilloscope as an output device, was probably one of the very first interactive images: On the circular screen of the oscilloscope, a deep horizontal “baseline” could be seen glowing on a dark background, in the middle of which a small vertical line rose up as a “net”. Above this, a luminous dot moved as a “ball”, the movement of which caused a slight tail to appear on the monitor (Fig. 1). The direction of the movement was reflected on the lines and followed a virtual gravitational force. In particular, however, it could be influenced by means of the buttons so that a game reminiscent of table tennis could be played between two users. On the concept of interactive systems Interactivity is, thus, not simply attributed to specific images as such; rather, it is generated by the interactive technical system, with the help of which sequences are presented from a predetermined or on-demand generated set of (“normal”) images. The term ‘interactive’ is somewhat awkward, as it connotes both ‘interaction’ and ‘medial interactivity’, neither of which is actually meant. In the current context, it is really only a matter of ‘technical interactivity’, which initially means that a technical device reacts to user activities at all or even in a particularly pronounced way. In the early days of computer science, the “interaction” between humans and computers was essentially limited to first connecting a previously thoroughly prepared program – computer use was expensive, and the calculations were usually lengthy – in the form of punched cards or magnetic tapes, pressing a start button and waiting for the end of the calculation and the output of the result. Intervention during the computer run was not intended (and initially, apart from hard abort, not even possible). That essentially only changed at the beginning of the 1960s, and the paradigm shifted away from such 'batch jobs', as they were called, to interactive computer systems that could respond directly to user input at any time ([Licklider 1960a]Licklider, Joseph C. R. (1960): Man-Computer Symbiosis. IRE Transactions on Human Factors in Electronics, 1, 1. ). In the case of the media-based computer systems considered here, we are dealing with a particularly pronounced form of reactivity, which is also associated with certain specific features of the communication acts carried out via it. When we talk about interactive computer systems, we are referring, in particular, to quaternary media. In that type of media, several very different communication actions are intertwined: While the user “interacts” with the device (metaphorically), they also communicate with themselves in primary media, as the output depends decisively on their input; in addition, they are in secondary media communication with the author of the system, who is of course also responsible for the content and formal aspects of the respective outputs and their dependence on user input. Interactive images as quaternary media Not every user dependency leads to interactivity in the sense meant here. After all, the oscilloscope of a lie detector also produces graphic results that depend on certain physiological reactions of the test person or the questions asked by the experimenter in real-time. A characteristic of interactive images in the sense of a quaternary medium lies in the ‘direct manipulation’ as it is called ([Shneiderman 1983a]Shneiderman, B. (1983): Direct Manipulation - A Step Beyond Programming Languages. IEEE Computer, 16, 8. ). This term refers to the fact that all objects (in the broad sense) referred to in a computer program, including images, for example, are, after all, merely in the form of coded descriptions. Therefore, changes to those are not really manipulations of corresponding objects, but rather manipulations of the coded descriptions of such objects, i.e., the approximate conversion of one text into another text of the same type according to a certain rule. Direct manipulation occurs when the user is largely enabled to carry out such manipulations as if the corresponding objects were actually being changed instead of the descriptions. In the case of interactive images, that means, provided that the image is actually shown to the user as an image and not as an image-coding data structure (i.e., a corresponding graphic output device must be available), the user must be able to handle these immaterial images at least approximately in the same way as they are used to with material images. Special input devices have been developed for this purpose – from mouse and light pen to virtual buttons, sliders, and data gloves. Consequently, the computer system must feed back the input to the output in very fast cycles, namely so fast that the actual processing time required to analyze the input, make corresponding changes to the coded image description, and output the resulting description as an image is no longer (or hardly) noticeable to the user. The manipulation is direct in two respects: (i) (apparently) not via the detour of informatic coding, and (ii) in its effect (almost) without delay[6]. When presenting images using interactive systems, two levels of direct manipulation can be distinguished: (a) Influencing the presentation parameters: The image is thus manipulated as an image. This includes, in particular, changing the size and rotation, changing the contrast, or embedding in larger layouts by means of simple hand movements by the user. The fact that an image can be “dragged” to a certain position with the mouse, enlarged by “pulling the corners”, and rotated by moving the mouse after a certain mouse click, for example, are usually basic options for image editing software. Figure 2: Sketch of the difference between computer graphic image generation when the images are (b) generated in an interactive system or (a) not so (b) Influencing the displayed image content: Depending on the image type, this involves (i) a selection from a given set according to variable content criteria, (ii) the computer-graphic generation of corresponding images from a modifiable 3D model (Fig. 2) or (iii) computer visualization from influenceable data sets. Direct manipulations of 3D models, which in turn can be differentiated into three subtypes, are particularly revealing: (b1) Influencing the visualization type (changing the rendering algorithm): In addition to a number of so-called photorealistic rendering algorithms, the calculation of the two-dimensional projection from the 3D model can make use of a variety of non-photorealistic algorithms so that the resulting image can appear in a wide range of stylistic variations (cf. [Sachs-Hombach & Schirra 2002a]Sachs-Hombach, Klaus & Schirra, Jörg R.J. (2002): Selecting Styles for Tele-Rendering: Toward a Rhetoric in Computational Visualistics. In: Butz, A. & Krüger, A. & Olivier, P. & Schlechtweg, S. & Zhou, M. (Hg.), Proc. 2nd International Symposium on Smart Graphics. ACM Press, Hawthorne, NY. ). In this way, the viewer's attention can be drawn to specific parts of the image content (or to the image character as such; ⊳ Image in reflexive use). (b2) Influencing the model (transformations of depicted objects, lighting): This type of modification forms a basis for the immersion effects of cyberspace. By allowing a user to influence the objects presented in the image (almost) as if they were real objects, for instance, by using a mouse or data glove to push, pull, or turn them with a hand movement, the difference between the image of the object and its unmediated perception is at least partially eliminated (⊳ [[dezeptiver und immersiver Modus|deceptive and immersive mode]). Influencing the “ball” in «Tennis for Two», “opening” a “door” in a modern computer game, or “moving” a file on a “desktop” are typical examples of this type of manipulation. (b3) Influencing the perspective (movements and parameters of the virtual “camera”); although these manipulations are at least partially equivalent in effect to the changes mentioned under (a), they do not affect the reception situation of the image, but rather its production situation. In combination with (b2), however, the decisive prerequisite for immersion in cyberspace arises: the virtual camera becomes the user's “eye”, so to speak, which the user can move “directly” through the virtual world determined by the 3D model (⊳ [[Virtualität|Virtuality), if not in the same way as their own, then at least in close analogy to their own body orientation and movement. Wie bei allen quartären Medien stellt sich auch bei inter­aktiven Bildern insbe­sondere die Frage, wer hier eigent­lich auf welcher Ebene mit wem kommu­niziert. Einer­seits besteht eine Ähn­lich­keit zu Sekun­därme­dien, inso­fern die (meist unbe­kannten) Auto­ren des inter­aktiven Systems (in Abbil­dung 2 als ‘die Compu­tervi­sualis­ten’ bezeich­net) als die eigent­lichen Sender betrach­tet werden können. Indem aber auch der Nutzer des Systems wenig­stens partiell zugleich als Sender und Emp­fänger jener Inter­aktionen auftritt, da er sich ja selbst mit dem erzeug­ten Bild etwas zeigen will (z.B. eine Route in der inter­aktiven Straßen­karte), ergibt sich eben­so eine Verwandt­schaft zu Primär­medien mit der Mög­lich­keit von direk­ter Deixis: Da die Auswahl der aktu­ali­sierten Zeichen­handlung durch das System in der aktu­ellen Situ­ation erfolgt, können ent­sprechen­de Zeige­gesten und deik­tische Äuße­rungen, Zugang des Systems zu den dort vorhan­denen Gegen­ständen voraus­gesetzt, darin vor­kommen. Diese Les­arten sind untrenn­bar in­einan­der ver­schlungen. Inter­aktions-, Selbst- und Sach­bezüge vari­ieren ent­sprechend. Es ist daher auch eine Haupt­aufgabe bei der Konstruk­tion solcher Syste­me, durch Kompo­nenten, wie etwa Nutzer­modelle, eine möglichst gute Passung mit den Hand­lungen und Kommu­nika­tions­inten­tionen des Nutzers sicher­zustellen. Anderer­seits muss sich jeder Nutzer darüber im Klaren sein, dass es sich um eine durch ein hoch­komple­xes Medium vermit­telte Kommu­nika­tion handelt mit allen dadurch beding­ten Einschrän­kungen und Beson­derhei­ten, so sehr sie im Einzel­fall auch der Kommu­nika­tion in einem Primär­medium ähneln mag. . . Dauert ein bißchen! Abbildung 3: Bei­spiel für ein ein­fa­ches in­ter­ak­ti­ves Bild (aktuell leicht fehlerhaft) Ein einfaches Beispiel Ein verhältnismäßig einfaches Bei­spiel ist in diesem Glossar auf der Haupt­seite gegeben und wird in Abbil­dung 3 in etwas vari­ierter Form aufge­griffen: Die mit typo­graphi­schen Varian­ten als Wort­wolke wieder­gege­bene Liste der Kate­gorien, nach denen das Glossar orga­nisiert ist, re­agiert auf Bewe­gungen des Cursors über die Bild­fläche, die der Betrach­ter mit der Maus auslöst. Die Wort­wolke beginnt, sich scheinbar im drei­dimen­siona­len Raum zu drehen, wobei Rota­tionswin­kel und -geschwin­digkeit in Abhän­gigkeit von der jewei­ligen Distanz der vom aktu­ellen Benut­zer gerade gewähl­ten Cursor­position zum Bild­mittel­punkt bestimmt werden. Würde der Cursor exakt auf dem Mittel­punkt posi­tioniert, würde die Bewe­gung auf­hören. Das tut sie im Übrigen auch von selbst nach einer ausge­dehnten Verlang­samungs­phase, wenn der Cursor die Bild­fläche verlässt. Siehe auch: Bildinhalt Bild in reflexiver Verwendung Bildsyntax Computergraphik Cyberspace dezeptiver und immersiver Modus digitale Medien Film Ikonische Differenz Interaktion und Kommunikation Interaktions-, Selbst- und Sachbezug Notation Typologien der Medien Virtualität

Anmerkungen Literatur [Licklider 1960a]Licklider, Joseph C. R. (1960): Man-Computer Symbiosis. IRE Transactions on Human Factors in Electronics, 1, 1.[Sachs-Hombach & Schirra 2002a]Sachs-Hombach, Klaus & Schirra, Jörg R.J. (2002): Selecting Styles for Tele-Rendering: Toward a Rhetoric in Computational Visualistics. In: Butz, A. & Krüger, A. & Olivier, P. & Schlechtweg, S. & Zhou, M. (Hg.), Proc. 2nd International Symposium on Smart Graphics. ACM Press, Hawthorne, NY.[Shneiderman 1983a]Shneiderman, B. (1983): Direct Manipulation - A Step Beyond Programming Languages. IEEE Computer, 16, 8.[Van Deemter 1998a]Van Deemter, K (1998): Retrieving Pictures for Document Generation. In: Hiemstra, D. & de Jong, F.M.G. & Netter, K. (Hg.), Proc. of 14th Workshop on Language Technology. University of Twente, Twente. Ausgabe 1: 2013 Verantwortlich: Schirra, Jörg R.J. Lektorat: Halawa, Mark Seitenbearbeitungen durch: Joerg R.J. Schirra und Marcel Lemmes — (Hinweis) Zitierhinweis: [Schirra 2013g-n]Schirra, Jörg R.J. (2013). Interaktives Bild. (Ausg. 1). In: Schirra, J.R.J.; Halawa, M. & Liebsch, D. (Hg.), Glossar der Bildphilosophie. (2012-2026). [bildglossar.org/index.php?title=Interaktives_Bild]. Webadresse: bildglossar.org/index.php?title=Interaktives_Bild Schirra, Jörg R.J. (2013). Interactive Images. (Ausg. 1). In: Schirra, J.R.J.; Halawa, M. & Liebsch, D. (Hg.), Glossar der Bildphilosophie. (2012-2026). [bildglossar.org/index.php?title=Glossar-English:Interactive_Images].