Invisible Surface Research Articles

Hierarchical face cluster partitioning of polygonal surfaces and high‐speed rendering

AbstractA computer's rendering capacity cannot handle the increased amount of data when rendering high‐quality, three‐dimensional computer graphic images. This results in problems such as rendering not being possible depending on the subject image, or the rendering speed dropping too far. To resolve these problems, we propose a method for generating a new hierarchical three‐dimensional data structure based on recursive face cluster partitioning, and a high‐speed rendering data extraction algorithm using that data structure. In the proposed algorithm, local resolution control using the approximating polygon of a face cluster, and precise invisible surface culling using the bounding volume of the face cluster can be executed in parallel. High‐speed rendering can be performed with little deterioration in quality, even for a large amount of data. The effectiveness of this algorithm was confirmed with a local resolution control experiment and a large‐scale three‐dimensional model rendering experiment. © 2007 Wiley Periodicals, Inc. Syst Comp Jpn, 38(8): 32– 43, 2007; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/scj.20581

Mapping the World: Justin, Tatian, Lucian, and the Second Sophistic

In the late 1960s, African American children in Boston were asked to draw maps of their neighborhood, near the old Mission Hill housing project. The housing project, largely white at the time, took up a large part of their hand-drawn maps, but was figured in various ways as a big blank: a no-man's land, a topography absent of marks or monuments. The streets around it, as well as schools, restaurants, and stores, were often carefully and clearly articulated, but the housing project itself was an open, unmarked rectangle. Recent critical geographers have been interested in the way “people's spatial behaviour is shaped by the hills and valleys of the invisible information and environmental stress surfaces over them.” Landscape and the built environment of the city are not neutral, but have their own rhetoric, exerting influence on the bodies of those who move through them. And humans map and interpret space, understanding and defining the limits of their known world through the movements of their bodies.

IGUANA: a high-performance 2D and 3D visualisation system

The IGUANA project has developed visualisation tools for multiple high-energy experiments. At the core of IGUANA is a generic, high-performance visualisation system based on OpenInventor and OpenGL. This paper describes the back-end and a feature-rich 3D visualisation system built on it, as well as a new 2D visualisation system that can automatically generate 2D views from 3D data, for example to produce R/Z or X/Y detector displays from existing 3D display with little effort. IGUANA has collaborated with the open-source gl2ps project to create a high-quality vector postscript output that can produce true vector graphics output from any OpenGL 2D or 3D display, complete with surface shading and culling of invisible surfaces. We describe how it works. We also describe how one can measure the memory and performance costs of various OpenInventor constructs and how to test scene graphs. We present good patterns to follow and bad patterns to avoid. We have added more advanced tools such as per-object clipping, slicing, lighting or animation, as well as multiple linked views with OpenInventor, and describe them in this paper. We give details on how to edit object appearance efficiently and easily, and even dynamically as a function of object properties, with instant visual feedback to the user.

Biofunctionalized polymer surfaces exhibiting minimal interaction towards immobilized proteins.

An invisible surface: Single protein molecules were immobilized on a cross-linked polymer surface (see cartoon), and imaged using fluorescence resonance energy transfer (FRET). The surface not only maintained the correct conformation of the protein molecules, but also allowed them to be unfolded and refolded fifty times consecutively. Moreover, the measured δG, cooperativity and the transition midpoint in guanidinium chloride of the unfolding-folding transition on the surface was identical to the protein in solution. Thus, the surface is energetically ‘invisible’ to the folding protein.

Kriging the potential tree level in Norway

The tree line is the upper margin of the subalpine forest where the trees become dwarfed or are absent (Howard &,Mitchell 1985). On topographic maps, the tree line divides the landscape into two uniform regions which are often referred to as ‘above’ and ‘below’ the tree line. The teminology implies a notion of the tree line as the physical manifestation of a continuous surface describing a potential tree level. The tree level exists globally, while the tree line only appears as a contour line where the tree level intersects the topography. The tree level can be thought of as a continuous but invisible surface. This surface cuts through the landscape along the tree line. The area below this surface is described as ‘below the tree line’, while areas above the surface are ‘above the tree line’.

The case for low surface brightness galaxies as the absorbers in QSO Mg II systems

We re-examine the case for numerous invisible low surface brightness galaxies (LSBGs), rather than rare but huge galactic haloes, as the absorbers responsible for a large fraction of the metal-line systems in the spectra of distant QSOs. In particular we find that the supposed best evidence for huge haloes, i.e. the direct observation of giant galaxies at projected distances of a few Holmberg radii from the QSO line of sight, can be explained by the normal clustering of galaxies near an (invisible) LSBG absorber directly in the line of sight to the QSO. We further point out that the most recent observations of the LSBG population indicate that we should expect a very high total cross-section for this population compared to the conventional population of 'normal' galaxies. In addition, adoption of the LSBG hypothesis removes several difficulties which occur in the 'conventional' picture, such as the unaccountably high average luminosity of the giant absorbers, the enormous size of the haloes required and the lack of correlation of the metal-line equivalent width and the QSO-giant galaxy separation. Perhaps most compelling of all, though, is the fact that the LSBG hypothesis simply explains the fact that searches for bright galaxies near QSOs with metal-line systems usually succeed (there is usually a bright galaxy somewhere near the absorbing LSBG), while searches for metal-line systems in QSOs projected a few Holmberg radii from a giant galaxy usually fail (no neighbouring LSBG happens to be in precisely the right place).

Reconstruction of three-dimensional surfaces from two-dimensional binary images

The authors describe a method for reconstruction of three-dimensional visible and invisible opaque surfaces using moving shadows. An object whose shape is to be determined is placed on a reference surface. A beam of substantially parallel rays of light is projected at the object at a set of different angles relative to the reference surface. Using a camera which is placed above the reference surface, the shadows cast by the object for each angle are transferred to a computer. A three-dimensional binary level shadow diagram (3DBL shadowgram) is formed and analyzed. The shadowgram has some features which make the reconstruction very simple: a section of the 3DBL shadowgram, referred to as a 2DBL shadowgram, can be used to determine the heights of points of the object to be reconstructed. Further analysis of some curves of the shadowgram can be used for the partial reconstruction of invisible surfaces. A set of experimental results to test the effects of the threshold, camera resolution, and the number of pictures demonstrates the robustness and usefulness of the method.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The Planet Venus

This book is not so much for the space scientist looking for background material for research as it is for one interested in the history of planetary exploration. The first half (∼100 pps) is devoted to studies of Venus before the space age, starting at several hundred years BC. It is obvious from the multitude of detailed descriptions of observers' accounts that considerable library research went into this section. While sometimes tedious, this chronology of Venus research is punctuated with amusing facts. While many may know about the Velikovsky theory of the cometary origin of the planet, few may know that Lowell drew pictures of Cytherian canals similar to the canals of Mars or that Frederick the Great of Prussia proposed to name the (once suspected) satellite of Venus D'Alembert, after the mathematician. An equally amusing appendix shows the ups and downs of the rotation period of this planet with the invisible surface. Much attention is focused on early telescope observations, the ashen light, and transits of Venus. At the end of this half, one appreciates that Venus has played a fairly important role in history in the areas of religion, science, and technology.

Condensation and mould growth in dwellings—parametric and field study

This paper presents a parametric study of the surface condensation problem in dwellings, which shows that in coastal regions with mild winter climate, absorbed surface condensation is probably unavoidable. The actual extent and severity of mould growth problems, which are due to the invisible surface condensation, were studied by means of a post-occupancy survey in 200 dwellings. Statistical analysis revealed that the major factors which affect the mould problem are: location and orientation of the dwellings, occupancy density, cooking habits and type of wall covering.

ON A LANDFORM CLASSIFICATION AND SOME PROBLEMS OF TERMINOLOGY

A paleogeomorphologist proposes a classification of the earth's landforms that would reflect the shaping of surface relief as a continuous process since the beginnings of the earth. In his view, the relief of former outer surfaces of the earth, now invisible to the observer, needs to be included in such a classification on the same basis as the relief of the earth's present surface. Accordingly all of the earth's relief forms are broken down into two basic categories: visible and invisible relief. Visible relief includes both contemporary landform types, shaped by on-going processes, and ancient landforms, including half-buried, relict and exhumed forms. The ancient reflief of invisible surfaces falls into buried, transformed buried and reconstructed types. The term “buried”, in contrast to present practice, needs to be restricted to invisible relief that has remained virtually intact after burial (under a sedimentary mantle, continental ice or the waters of oceans and large lakes). Any invisible relief t...

Electrical porcelain: I. Testing with a high-frequency oscillator. II. The problematical points of manufacture. III. Experiences and experimental investigations

Part I treats of the reasons for using the high frequency oscillator for testing porcelain insulators. The oscillator is a combination of a 60-cycle transformer, a condenser, a spark gap, and an oscillation or coreless transformer. The 60-cycle potential charges the condenser and the condenser discharges through the gap and the coreless transformer. This sets up high frequency wave trains of the same nature as the wave trains that take place on the transmission line. This high frequency potential strain is the only kind that damages the insulators. The 60-cycle potential is always far below the puncture potential and arc-over potential of the insulators. In Part II it is shown that the principal factors in the manufacture of porcelain which affect the final product are: 1. The choice of ingredients, — ball clay, china clay, feldspar, and flint. 2. Is the problem involved in getting a homogeneous mixture of these pulverized materials. 3. Is the problem of drying out the moisture without causing unequal contractions which crack the green porcelain. 4. Is the early dehydration in the furnace in which as much as 14 per cent of moisture is given out. 5. Proper time and temperature for vitrification. The mechanical processes through which porcelain is carried are of the greatest importance in getting good electrical porcelain. It can be stated that defective porcelains are in general due to the accidents of manufacture, the dielectric strength of all the porcelains being passably good except for flaws. Part III includes data on tests carried out mostly with the high-frequency outfit. An electrical method is shown of producing failure along invisible cleavage surfaces in the porcelain body. This examination should be useful to the porcelain manufacturer to indicate how nearly the porcelain is approaching to a weakness which will cause the rejection of the porcelain piece. Another method, using potential gradient to investigate the homogeneity of the porcelain, may be found of use in determining the efficiency of the pug mill which is used to mix the ingredients when the porcelain is in the early plastic stage.

The Movements of Floating Particles

IN reply to Mr. Archdall Reid (March 19, p. 60) I should say that the effects which he describes are the natural behaviour of a contaminated surface. A greasy contamination of the right order of magnitude tends to spread itself uniformly over the surface. If when the liquid in the saucer sways over to one side, the surface layer went with it, the contamination would be concentrated upon that side and diluted upon the other. Such a displacement is resisted. The invisible surface contamination remains nearly equally distributed, and the fact is witnessed by the visible particles floating upon it.