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Start date: 1980 × Author: Herman, Ivan ×

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    A Means to Improve the GKS-3D/PHIGS Output Pipeline Implementation
    (Eurographics Association, 1987) Herman, Ivan; Reviczky, Janos
    The output pipeline of GKS-3D/PHIGS isexamined to find some possible points where the implementation could be improved to raise efficiency while remaining strictly within the scope of the Standards. Some interesting results are presented in the paper which have led to a 25-30% improvement in speed when compared to a more conservative implementation.
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    On The Projective Invariant Representation of Conies in Computer Graphics
    (Blackwell Publishing Ltd and the Eurographics Association, 1989) Herman, Ivan
    A general formulation for conies and conic arcs for the purpose of computer graphics is given, based on principles and theorems of projective geometry. This approach allows the approximation of these curves by line segments to be postponed in the graphics output pipeline- it results in a more compact storage, faster approximation algorithms and smoother outlook of the curves.
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    2.5 Dimensional Graphics Systems
    (Eurographics Association, 1989) Herman, Ivan
    The outline of an extension of traditional 2D graphics systems is given. This extension is aimed at supporting a three dimensional application program, without incorporating full viewing into the general graphics system itself. The resulting system might be very advantageous for large application programs which have their own three dimensional facilities.
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    Modelling Clip: Some More Results
    (Blackwell Publishing Ltd and the Eurographics Association, 1990) Hubl, Josef; Herman, Ivan
    The modedling clip of the PHIGS ISO Standard is mathematically analysed. The most important result of this analysis is the fact that the projective image of a modding clip body (that is a not necessarily bounded convex body in space) is simply the union of two convex bodies. Furthermore, it will also be proved that in some cases one of these two bodies is empty. This fact makes the implementation of the modelling clip fairly straightforward and makes it also possible to use all already existing results on clipping against general convex bodies without change.
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    Web 2D Graphics: State-of-the-Art
    (Eurographics Association, 2001) Duce, David; Herman, Ivan; Hopgood, Bob
    The early browsers for the Web were predominantly aimed at retrieval of textual information. Tim Berners-Lee's original browser for the NeXT computer did allow images to be viewed but they popped up in a separate window and were not an integral part of the Web page. In January 1993, the Mosaic browser was released by NCSA. The browser was simple to download and, by the Autumn of 1993, was available for X workstations, PCs and the Mac. From 50 Web servers at the start of 1993, Web traffic had risen to 1% of internet traffic by October and 2.5% by the end of the year. About a million downloads of the Mosaic browser took place that year. In February of 1993, Mark Andreessen proposed the element as an extension to Mosaic's HTML to provide a way of adding images to Web pages. In 1994, Dave Raggett developed an X-browser that allowed text to flow around images and tables and from then on images were an accepted part of the Web page. Web pages became glossier and the enormous growth of the Web started [1] [2]. Organisations could customise their home pages with the company logo. Maps, albeit images, could be added to show how to reach the organisation. Its products could be displayed on the Web. Eventually, the Web would become a major commercial outlet.
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    SVG Linearization and Accessibility
    (Blackwell Publishers, Inc and the Eurographics Association, 2002) Herman, Ivan; Dardailler, Daniel
    The usage of SVG (Scaleable Vector Graphics) creates new possibilities as well as new challenges for theaccessibility of Web sites. This paper presents a metadata vocabulary to describe the information content ofan SVG file geared towards accessibility. When used with a suitable tool, this metadata description can helpin generating a textual ('linear') version of the content, which can be used for users with disabilities or withnon-visual devices.Although this paper concentrates on SVG, i.e. on graphics on the Web, the metadata approach and vocabularypresented below can be applied in relation to other technologies, too. Indeed, accessibility issues have a muchwider significance, and have an effect on areas like CAD, cartography, or information visualization. Hence, theexperiences of the work presented below may also be useful for practitioners in other areas.ACM CSS: I.3.4 Graphics Utilities-Graphics Packages, I.3.6 Methodology and Techniques-Graphics datastructures and data types, Standards, K.4.2 Social Issues-Assistive technologies for persons with disabilities
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    Eurographics 90 Tutorials Montreux - Switzerland - September 3-4, 1990
    (Blackwell Publishing Ltd and the Eurographics Association, 1990) Herman, Ivan
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    Tree Visualisation and Navigation Clues for Information Visualisation
    (Blackwell Publishers Ltd and the Eurographics Association, 1998) Herman, Ivan; Delest, Maylis; Melancon, Guy
    Information visualisation often requires good navigation aids on large trees, which represent the underlying abstract information. Using trees for information visualisation requires novel user interface techniques, visual clues, and navigational aids. This paper describes a visual clue: using the so-called Strahler numbers, a map is provided that indicates which parts of the tree are interesting. A second idea is that of "folding" away subtrees that are too "different" in some sense, thereby reducing the visual complexity of the tree. Examples are given demonstrating these techniques, and what the further challenges in this area are.
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    The GKS Input Model in Manifold
    (Blackwell Science Ltd and the Eurographics Association, 1991) Soede, Dirk; Arbab, Farhad; Herman, Ivan; Ten Hagen, Paul J. W.
    This paper describes the specification of the GKS input model in Manifold. The aim of the work reported in this paper was two-fold: first, to review the communication patterns implied by the GKS input model, and second, to evaluate the suitability of the Manifold language as a tool for defining complex dynamic interaction patterns that are common in non-trivial user interfaces.The GKS input model is also adopted by all more recent ISO graphics standard documents. A more formal scrutiny of the inter-communication of the components of this model, excluding the implementation details of their functionality, is instructive in itself. It can reveal directions for improvement of its shortcomings and for generalization of its strengths for the ongoing effort to define the functionality of future graphics packages.Manifold is a language for describing inter-process communications. Processes in Manifold communicate by means of buffered communication links called streams and by reacting to events raised asynchronously by other processes. Our experience shows that Manifold is a promising tool for describing systems of cooperating parallel processes. Our Manifold specification of the GKS input model offers a very flexible way to structure user defined logical input devices. Furthermore, it is simple and modular enough to allow easy extensions to include more functionality by local modifications. As such, it can serve as a basis for possible extensions and enhancements envisioned for future graphics packages.1987 CR Categories: C.1.2, C.1.3, C.2.m, D.1.3, F.1.2, I.1.3, I.3.6, I.3.4.1885 Mathematical Subject Classification: 68N99, 68Q10,68U05.
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    Response to Morten Zachrisen s Note
    (Blackwell Publishing Ltd and the Eurographics Association, 1989) Herman, Ivan