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Über dieses Buch

Pictures are at the heart of how we communicate with computers, emblematic of our cur­ rent fascination with multimedia and web-based computing. Nevertheless, most of us know far less about pictures and the way in which they work than we know about the text that often accompanies them. In an attempt to understand pictures, perhaps the most fundamental question we can ask is, "What is a picture?" What is it that objects as di­ verse as icons, bar charts, paintings, and photographs have in common that makes us refer to all of them as pictures? And what is it about pictures that convinces us to use them instead of, or in addition to, text? We often talk about how pictures "depict" things. But, even the process of depiction seems to differ from one picture to another. On a computer, we may use a paint system to guide a virtual brush over the screen, a video camera to capture a live image, a spread­ sheet to automatically generate a corresponding bar chart, or a rendering system that models the interactions of synthetic lights, objects, and cameras. Is there some un­ derlying property that these processes all share? Computer scientists are used to thinking of pictures in terms of their representation: an array of pixels, a list or hierarchy of graphics primitives, or even a program written in a language such as PostScript.

Inhaltsverzeichnis

Frontmatter

Preliminaries

Frontmatter

Chapter 1. Introduction

Abstract
Computer graphics today is a field surrounded by an aura of perfection. Sophisticated tools have been developed for constructing data structures within a computer which describe the geometry of objects in a precise way. The resultant models form the input to Tenderers, which produce visualizations of the objects. These visualizations are, in turn, generally intended to mimic the task of a camera. Thus it is possible to generate images synthetically which resemble photographs of real scenes with such exactness that only a trained eye can tell the images apart. Even very complex scenes can be generated convincingly (Figure 1.1).
Christine Strothotte, Thomas Strothotte

Fundamentals

Frontmatter

Chapter 2. Pictures in Computer Systems

Abstract
Pictures appear on today’s computer screens in many areas of application. Their use varies from decoration — as they appear in the background of some desktop applications — to records of important information, such as in satellite photos of environmentally sensitive areas.
Christine Strothotte, Thomas Strothotte

Chapter 3. Classification of Pictures

Abstract
Pictures were the first form of written communication when human beings wrote their emotions, experiences, memories, and hopes on cave walls thousands of years ago. To remind the reader that cave paintings are the origin of our contemporary pictures, a collection of petroglyphs from all over the world is presented in this book.
Christine Strothotte, Thomas Strothotte

Chapter 4. Picture Processing by Humans

Abstract
Pictures processing depends on a variety of conditions. Two of these are the environment and context of the picture and the knowledge of the observer. Let us have a look at van Gogh’s “Crows over the corn field” in Figure 4.1.
Christine Strothotte, Thomas Strothotte

Chapter 5. Information Flow During Human-Computer Interaction

Abstract
Whenever a user operates a computer, information flows across the interface between the two. But what is the nature of this information? How does it flow, how can this flow be quantified? How does the context affect the flow of information? To what extent does the flow depend on the user’s competence before beginning the session on the computer? In this chapter, we will address these and related questions. The goal will be to devise a framework for designing and analyzing human-computer dialogues.
Christine Strothotte, Thomas Strothotte

Abstract-Graphical Pictures

Frontmatter

Chapter 6. Abstract-Graphical Pictures and Some Applications

Abstract
In Section 3.3.1 we defined an abstract-graphical picture as a presentation of properties of reality and relations in reality that are invisible to humans. This includes pictures of the non-visible interna of real systems (see Figure 6.1) as well as non-real objects which only exist in a person’s imagination.
Christine Strothotte, Thomas Strothotte

Chapter 7. Analysis of Abstract-Graphical Pictures

Abstract
We now turn to the more practical issue of making the information encoded in abstract-graphical pictures available to interactive systems. The problem is that while such pictures usually present information in a well-structured manner amenable to processing by machine, the vast majority of pictorial materials are stored only on paper, or, if within a computer, then in a data format (like bitmaps) that is difficult to access directly. This access is difficult because the structure must first be derived. While this is often trivial for a human reader, it can be hard to do with an algorithm. In this chapter, we develop a user-supported methodology to carry out this task.
Christine Strothotte, Thomas Strothotte

Chapter 8. Users’ Analysis and Criticism of Abstract-Graphical Pictures

Abstract
The stage has now been set for a study of ways in which end-users of interactive systems can work with abstract-graphical pictures. Having shed light on how users understand pictures (Chapter 4) and mechanisms for using pictures to convey information (Chapter 5), we now want the user and the computer to join forces via the pictures presented. In order for abstract-graphical pictures to link up the user and the computer effectively, we need convincing ways in which the user can close the circuit by giving his or her input a new quality with respect to the pictures.
Christine Strothotte, Thomas Strothotte

Chapter 9. Viewpoint Descriptions

Abstract
Arnheim’s question pertaining to what we really know about what learners see when examining pictures (recall Section 8.1.3) cannot be answered with the technique of oracles alone, since only certain aspects of that what a user sees are relevant. Indeed, oracles can be viewed as a very narrow answer to the question of what a user actually sees. A more complete answer can be developed with viewpoint descriptions, in which a user describes more fully what he or she sees in an animation.
Christine Strothotte, Thomas Strothotte

Pictograms

Frontmatter

Chapter 10. The Nature of Pictograms and Their Use

Abstract
We have illustrated the wide variety of pictures with 127 examples so far. Chapter 3 presented a classification scheme for pictograms, abstract-graphical pictures, and presentational pictures, but the description of pictograms remained rather vague. We now investigate pictograms in somewhat more detail with respect to what information can be transmitted or transputed with them and their ability to provoke normalization demands.
Christine Strothotte, Thomas Strothotte

Chapter 11. Pictograms as Words

Abstract
Having studied pictograms from the point of view of their pragmatics, we are now in a position to take the next step and learn more about the relationship between pictograms and language.
Christine Strothotte, Thomas Strothotte

Chapter 12. Pictograms as Pictures

Abstract
We now turn to a discussion of pictograms from the point of view of their being pictures. This extends the idea in Chapter 11 that pictograms are in most cases only a pictorial presentation of words. Our current topic can be seen as a study of the ramifications of the etymology of the word pictogram, which is composed of the Latin pictus (picture) and the Greek graphein (to write), with the consequence that etymologically the word pictogram means ‘written picture’. What kinds of pictures are pictograms? What restrictions must be imposed on presentational pictures or on abstract-graphical ones so that the results qualify as pictograms? We will try to find satisfactory answers to these questions using a variety of examples.
Christine Strothotte, Thomas Strothotte

Chapter 13. Formal Representations and Informal Presentations

Abstract
We now turn to the transition from pictures composed of and including graphical symbols to more complex pictorial presentations, whose meaning can no longer be captured easily by Fregean structures. This immediately raises the issue of formalization: To what extent can or even should information encoded in pictures be represented formally, and how can the informal context, which traditionally has been handled implicitly in humancomputer interaction, be treated algorithmically and conveyed to users?
Christine Strothotte, Thomas Strothotte

Presentational Pictures

Frontmatter

Chapter 14. Image Generation

Abstract
Presentational pictures can be characterized by the fact that they are generally produced well in advance of being exhibited to an end-user. For example, a painter’s work is almost always first shown a long time after he or she has completed it, and the same is true for motion pictures. Computer with high-quality raster images have generally also followed this scheme of things, as the rendering has taken too long to be done while the user waits. Where rendering can be sped up to near real time, the computer itself must take on in this case the difficult task of deciding which piece of graphics will be presented next to the user, as there is no longer the opportunity for a human designer to be involved in every detail. Roughly speaking, it is this task that we refer to as image generation.
Christine Strothotte, Thomas Strothotte

Chapter 15. Alternative Rendering of Images

Abstract
Having studied systems which make use of various kinds of graphics, ranging from abstract-graphical to presentational pictures (in particular, photorealistic images), we now turn our attention to working situations in which graphics are actually used and examine the effect of the form of graphics on users. Our interest will be on the overall message users ascertain from viewing the graphics, particularly on the transputed information and how this can be affected
Christine Strothotte, Thomas Strothotte

Chapter 16. Tactile Computer Graphics

Abstract
The term “computer graphics” has traditionally been used to refer to images produced for visual inspection on computer screens, paper, or other media like celluloid and foils. In recent years, the computer graphics community has extended its scope to include richer interaction, such as in virtual reality systems. Of interest are no longer just visual impressions, but also sounds and users’ movements to accompany interactive graphics.
Christine Strothotte, Thomas Strothotte

Chapter 17. Immersive Systems

Abstract
In recent years, a great deal of hype has been generated around the term “virtual reality”. The news media jumped onto the bandwagon and raised the expectations of the general public, and even members of the scientific community, well beyond reason. Despite the fact that this area of endeavor has failed to deliver what was projected after the initial advances, some interesting concepts have been developed which show promise. Thus a book on pictures in human-computer interaction would not be complete without at least a brief look into this area. We will do so without claiming any kind of completeness; for a detailed analysis, books devoted entirely to the subject are recommended (for example, Rheingold 1991; Bryson 1992; and Earnshaw, Gigante, and Jones 1993). We will survey aspects we consider particularly relevant to the part of the interaction pertaining to pictures and language, following and extending the nomenclature of Henry and Furness (1993). We will argue for a certain amount of language to augment pictures in immersive systems.
Christine Strothotte, Thomas Strothotte

Epilogue

Frontmatter

Chapter 18. Pictures and Language

Abstract
In this chapter, we return to some of the more fundamental issues surrounding pictures. We draw on the terms we have developed to look back at the material we have studied. The goal is to shed more light on the relationship between pictures and language.
Christine Strothotte, Thomas Strothotte

Chapter 19. Quo vadis?

Abstract
Generally we assume that pictures represent the truth in some sense. Even though we have already determined that a picture has no truth value per se, it is only natural to trust photos to reproduce scenes in the same way as our eyes perceive the real scene. The aura of photography gives pictures a great deal of credibility.
Christine Strothotte, Thomas Strothotte

Backmatter

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