Interactive Graphics System Research Articles

Tectonic Evolution of the Northern Caribbean/Bahamas/Florida Region: Implications for Exploration

ABSTRACT The northern Caribbean/Florida/Bahamas region consists of (1) a major thrust belt striking from western Cuba to Puerto Rico and (2) a broad carbonate foreland to the north in Florida and the Bahamas. A major exploration problem in Florida and the Bahamas has been the interpretation of many anomalous vertical seismic features in the carbonate platform. Are they vertical faults or the effect of statics and paleokarst problems? If these features are true faults, uncertainties remain concerning fault geometry, timing, and trap potential. In order to clarify these uncertainties the following tectonic scenario was developed by (1) analyzing regional structure and stratigraphy and (2) testing palinspastic interpretations on an interactive 3D computer graphics system. Triassic/Jurassic. The study area serves as a transform zone in continental crust between the opening Central Atlantic and Gulf of Mexico basins. Continental crust is variably stretched between NW striking wrench faults and subsidiary NNE striking normal faults. By the latest Jurassic, the Gulf of Mexico stops opening and transform motion in the study area ceases. Early Cretaceous. Seafloor spreading begins east of Yucatan in the proto-Caribbean ocean and the proto-Cuba, Bahamas, and Florida area develops into a young continental margin sequence characterized by rapid subsidence and deposition of pelagic limestone (good source rocks). Mid Cretaceous. Changes in regional stresses surrounding the enlarging Atlantic Ocean disrupt the continental margin. Older rift and wrench-related structures in the basement reactivate and propagate into the overlying Neocomian section creating highs and lows at the surface. Late Cretaceous-Tertiary. The Cuban arc collides with the continental margin and forms a south-dipping thrust stack. Traps form in thrust-related anticlines that are charged as continental margin source rocks are overthrust and matured. Convergent stresses reactivate rift- and wrench-related structures in the foreland causing a jostling of crustal blocks. New faults propagate upward into overlying carbonates creating low-amplitude anticlinal closures. For explorationists, the tectonic scenario developed by this study suggests that in Florida/Bahamas, the anomalous seismic features in the carbonate platform are true vertical faults making this area more structurally complicated (but also more prospective) than previously recognized. End_of_Record - Last_Page 321-------

An interactive computer graphics system for the design of molded and orthopedic shoe lasts

The Department of Computer Science at North Carolina State University, with support from the Department of Veterans Affairs and National Aeronautics and Space Administration (NASA) Langley Research Center, has developed an interactive graphics program for the development of shoe lasts from digitized images of feet or digitized images of commercial shoe lasts. The program runs on a Sun 3/260 computer with a TAAC-1 graphics accelerator. The program contains operations for region addition and deletion, techniques for narrowing the ankle area, methods for toe extension, operations to allow for shoe inserts, etc. Once the operations by the user are complete, the program will resample the resulting last in a 512 x 512 array. The user is then allowed to select an error tolerance which will guide a data reduction program to represent the last as Coons patches. These patches are then transmitted to a milling machine which will cut the last.

Analysis of the CuKβX-Ray Diffraction Pattern of YAG (Yttrium Aluminium Garnet) by Numerical and Computerized Graphics Techniques

AbstractYttrium aluminium garnet, Y3A15O12– YAG, has a powder diffraction pattern that is easy to analyse in principle, but shows very interesting problems. These problems are revealed using an interactive graphics system, UNIRAS, intregated with some of the usual procedures for crystallographic data processing. For example, indexing with the APPLEMAN procedure is improved when the high-angle peaks are properly identified, and the cell parameters then refine to a high precision. Iterations between refinements and graphical analysis allows the operator to identify even some of the very weak peaks in the pattern. Using the peak positions from the refinement, the experimental data can be analyzed for instrumental aberrations and corrections can be applied to improve the accuracy of the cell parameter.

An interactive graphical system for surface property comparison

An interactive graphical system for surface property comparison

A detailed seismicity study of the Middle Mountain zone at Parkfield, California

Abstract In order to better understand the preparation zone of the predicted Parkfield earthquake, a detailed study of the seismicity at middle Mountain in the Parkfield, California, area was made using 71 digitally recorded earthquakes that located within, or close to, the Middle Mountain alert box. These earthquakes were retimed on an interactive graphics system. Based on these new arrival times, new station corrections were developed; however the data did not support changing the velocity model developed from refraction and 1966 aftershock data. The process of retiming the earthquakes and using the new station corrections reduced the rms travel-time residuals by 70 per cent to 0.025 sec, halved the location errors, and clustered the earthquakes closer to the surface trace of the San Andreas fault. The seismicity can be approximated by a plane on the scale of several kilometers, but at finer scales two clusters were discovered that show demonstrable width to the seismogenic zone. Previous workers had proposed a 5° bend in the fault at the hypocenter of the 1966 main shock on the basis of patterns in the first motion data in the 1966 aftershocks. We find that this pattern also exists in the first-motion data from 1969 to 1987, but the 5° bend was not evident in the hypocentral distribution. This suggests that a more complicated explanation is needed to explain the first-motion data. Fault plane solutions were determined for the 71 events and 69 of these were compatible with strike-slip motion on a vertical San Andreas fault. An event located in the north end of the study area co-locates with the strike-slip solutions and may be a thrust or oblique solution. The other earthquake, located 2½ kilometers northeast of the fault, has a thrust or NNE-SSW striking right lateral solution but can not be explained by a San Andreas style mechanism. Both possible solutions can be explained by structures observed in the geology.

Top Draw: A Structure Network Visualiser for PHIGS

AbstractThe Programmer's Hierarchical Interactive Graphics System (PHIGS) is an International Standard for computer graphics. PHIGS provides a flexible mechanism for creating hierarchical models from collections of directed acyclic graphs known as ‘structure networks’. In practice, the combination of powerful data structuring facilities and the ability to dynamically edit structure networks can lead to a potential complexity which makes models difficult to manage and maintain reliably.This paper presents TopDraw, a portable programming tool for visualising PHIGS structure networks, by automatically documenting their topology using diagrams. Drawing tidy representations of graphs algorithmically is a difficult problem, and most existing systems are large, complex and speciallsed The alternative approach taken in TopDraw is to use a fast, straightforward algorithm supplemented when necessary by an interactive 'tidief. A novel feature of TopDraw is that the diagrams it produces are themselves PHIGS structures, which the application may edit and manipdate as required. TopDraw is a component of the PHIGS Toolkit, an emerging set of portable integrated tools for PHIGS environments.

Synthetic image generation for application in ophthalmology and neuropsychology

Graphic stimuli with defined forms, colours and sizes can be used to evaluate the performance of the intact or defective human visual system. In the past, large numbers of tests based on visual stimuli have been developed and today some are being computerized in order to conduct complete diagnostic, preventive or therapeutic investigations in a consistent and efficient manner. After an introduction into the evolution of interactive computer graphic systems the selection criteria for computerized aids in the medical office are outlined and sample applications in ophthalmology and neuropsychology discussed. The experience gained using object-oriented and conventional software development environments is outlined and the results presented.

Strategies For The Visualization Of Geographic Time-Series Data

Strategies for the visual display and analysis of geographic time-series data may be spatial or nonspatial, single-view or multiple-view, static or dynamic. Labels for place names or other geographic metaphors can describe symbols on aspatial time-series charts. Single-static-map strategies incorporate the temporal dimension through techniques ranging from complex point symbols, or temporal glyphs, to generalized trend-surface or flow-linkage maps focusing on movement. The multiple-static-maps strategy juxtaposes two or more maps for a simultaneous visual comparison of time units, whereas the single-dynamic-map strategy either presents maps in a temporal sequence or shows the evolution of a geographic pattern through a temporally sequenced accretion of symbols. In contrast, the multiple-dynamic-maps strategy provides programmed sequences of multiple views or allows the viewer to interact with maps and statistical diagrams representing different instants or periods of time. Electronic graphics systems have added time to the cartographer's list of visual variables. This paper addresses the graphic portrayal of geographic time-series data. It explores a variety of graphic strategies for the simultaneous symbolic representation of time and space, and summarizes these strategies in a conceptual framework of potential use to cartographers, geographers, and graphic designers. These strategies range from statistical diagrams to maps to video animations to interactive graphics systems with which the analyst might freely manipulate time as a variable.

Computer graphics and layout design in documentation processes

Although drafting has been strongly supported by user-friendly, highly interactive graphical systems, today there is a challenge for a further, more sophisticated development. The aim of this development has to be a better integration of documentation processes into the entire framework of CAD. Such an aim can only be achieved by a higher degree of automation of documentation processes, by a derivation of documents (either on paper or as computer-internal representations) from more comprehensive models as basic results of CAD. In the case of graphical documents, this is a challenge for the inclusion of tools for automatic layout design into corresponding computer graphics systems. This paper considers problems arising from this challenge. The generation of graphical schematics requires the placement of symbols and the routing of connection lines. A program system is described that automatically transforms formal (textual) descriptions of certain industrial control processes into corresponding logic schematics by solving complex layout problems. A further topic is the automatic routing of connection lines in more general types of schematics by another software tool. The industrial application of these sophisticated computer graphics systems is discussed. With respect to workshop drawings, the paper concentrates on the layout of dimensions within views derived from 3D models. The paper concludes with an outlook on future work.

Field Application of Computer Graphics for Monitoring Borehole Trajectories

Summary A method to present directional wellbore trajectories graphically with microcomputers has been developed. This concept makes use of interactive computer graphics, enabling the user to view computer calculation results immediately. The source code was written in FORTRAN-77 and designed for use with microcomputers. Introduction The vertical and horizontal sections routinely used to evaluate directional wans are simple graphical displays that monitor the spatial position of a wellbore. These graphical profiles are limited in that investigation of multiple wellbores from a common surface point is very difficult. This problem is best resolved with the use of a computer and an interactive graphics computer program, such as the one discussed in this paper. Lutz and Kendle reported on the use of such a computer system, monitoring 1,190 directional wells drilled from marimade islands off California. This system provided speed and precision while eliminating the tedious drafting involved in manual calculations. The design parameters were also optimized to reduce drilling costs while minimizing interference between proposed and existing wells. However, their algorithms and source code were not published. Our work was suggested by techniques available in the computer-aided-drafting type interactive computer graphics systems. These user-friendly interactive systems allow quick recalculation and graphic display. These techniques were applied to a system of multiple wellbores to perform such tasks as translation, rotation, 3D clipping, and zoom onto an area of interest to give the viewer a variety of vantage points. The source code was written in FORTRAN-77. The program was compiled on an IBM PC in DOS and equipped with a graphic adapter, using the Microsoft FORTRAN Optimizing Compiler Version 4.0. It can easily be modified to fit particular user needs in addition to those demonstrated later in the paper. This source code provides a practical, usable program and eliminates the questionable reliability of undisclosed source codes. Theoretical Considerations First, the measured parameters of existing and proposed wells are entered into the computer program as measured depth and inclination and direction angles. These coordinates are immediately converted to an orthogonal system (i.e. north, east, and true vertical depth (TVD) by the minimumcurvature method. Then, the resulting coordinates are transformed to a world coordinate system (i.e., a right-hand Cartesian system where the y axis is vertically upward, the × axis is east, and the z axis is south), whose origin can be chosen by the user (see Fig. 1). Examples of origins are the center of a template for multiple wells or the surface location for a single well. The observer views this fixed coordinate system from a screen coordinate system that is free to move with respect to the world coordinate system. A vector in the world system is mapped to the screen system by applying observation transformations (i.e., scalings, rotations, and translations) and then mapping the screen system to the viewing area (see Fig. 2). Depending on the observation transformations chosen, some portions of the wells may require clipping at the boundaries of the viewing area. This allows the user to view the wellbore paths from a variety of spatial positions, such as from very far away to see all wellbores from surface to bottom or on horizontal planes to view relative positions of wells (see Fig. 3). In effect, the observer is looking through a square window of the world space that contains the information the user wishes to display (see Fig. 4). Then, the viewport is defined as a square portion of the viewing screen onto which the window contents are mapped. The viewport is essentially the 2D orthogonal projection of the contents of the window. Mathematically, the observation transformations, as indicated by primes, can be written as follows. For a translation, x'=x+a, y'=y+b, and z'=z+c, where a, b, and c are the translation parameters. For a rotation about the z axis, x'=x cos() -y sin(), y =x sin() +y cos(), and z'=z JPT December 1989 P. 1254^

A Method for the Representation, Evaluation and Display of CSG Models in PHIGS and PHIGS+

AbstractThe Programmer's Hierarchical Interactive Graphics System (PHIGS) is about to become a standard graphics system† which caters for the definition, display and modification of two and three‐dimensional graphical data. PHIGS, however, is mainly a wireframe system, and the PHIGS+, extensions to it have been put forward to allow the incorporation of shaded 3D graphics into PHIGS.,One area that is important to a large constituency and which has so far not been considered in PHIGS, and PHIGS+, is that of solid modelling. This paper addresses one aspect of solid modelling by describing a simple method for the representation, evaluation and display of Constructive Solid Geometry (CSG) models in PHIGS, and PHIGS+..

Refined crystal structure of cytoplasmic malate dehydrogenase at 2.5-A resolution.

The molecular structure of cytoplasmic malate dehydrogenase from pig heart has been refined by alternating rounds of restrained least-squares methods and model readjustment on an interactive graphics system. The resulting structure contains 333 amino acids in each of the two subunits, 2 NAD molecules, 471 solvent molecules, and 2 large noncovalently bound molecules that are assumed to be sulfate ions. The crystallographic study was done on one entire dimer without symmetry restraints. Analysis of the relative position of the two subunits shows that the dimer does not obey exact 2-fold rotational symmetry; instead, the subunits are related by a 173 degrees rotation. The structure results in a R factor of 16.7% for diffraction data between 6.0 and 2.5 A, and the rms deviations from ideal bond lengths and angles are 0.017 A and 2.57 degrees, respectively. The bound coenzyme in addition to hydrophobic interactions makes numerous hydrogen bonds that either are directly between NAD and the enzyme or are with solvent molecules, some of which in turn are hydrogen bonded to the enzyme. The carboxamide group of NAD is hydrogen bonded to the side chain of Asn-130 and via a water molecule to the backbone nitrogens of Leu-157 and Asp-158 and to the carbonyl oxygen of Leu-154. Asn-130 is one of the corner residues in a beta-turn that contains the lone cis peptide bond in cytoplasmic malate dehydrogenase, situated between Asn-130 and Pro-131. The active site histidine, His-186, is hydrogen bonded from nitrogen ND1 to the carboxylate of Asp-158 and from its nitrogen NE2 to the sulfate ion bound in the putative substrate binding site. In addition to interacting with the active site histidine, this sulfate ion is also hydrogen bonded to the guanidinium group of Arg-161, to the carboxamide group of Asn-140, and to the hydroxyl group of Ser-241. It is speculated that the substrate, malate or oxaloacetate, is bound in the sulfate binding site with the substrate 1-carboxyl hydrogen bonded to the guanidinium group of Arg-161.

The Controller Animation System

AbstractOne of the ways in which computer animation can be generated is to use interactive graphics systems. In this paper we describe Controller, an animation system of this type. We concentrate on the operation of Controller and detail how an animator can plan and choreograph the motion of objects and cameras. We have intended to provide a system that gives the animator as much control as possible subject to keeping die interface simple to operate.

A software system for optimum design and trajectory planning of robots

This paper describes an interactive graphic robot-simulation system that has been developed to carry out optimum design and to provide a robot-independent off-line motion-planning tool. The system includes model building, optimum design, trajectory planning and graphic display, and is capable of detecting collisions. Emphasis is given to graphics facilities (translation, scaling, removal of hidden lines, image animation, etc.). The system is highly interactive through a menu technique. It was written in Turbo Pascal and implemented on an IBM PC microcomputer.

WEMAP-a computer aided instructional tool for electromagnetics

WEMAP is an electromagnetic analysis computer code for teaching electromagnetics to power engineering students. WEMAP is a stand-alone interactive graphics system for electromagnetic analysis, which includes electrostatics, magnetostatics, eddy currents (time harmonic as well as transient), and permanent magnet fields. These capabilities are described, and examples are given to illustrate how this program can enhance the classroom presentation of some of the electromagnetic phenomena. >

Improved Printed Circuit Reliability by Risk Site Analysis

The circuit elements of every printed circuit board have the potential for failure during test and/or use. These failures can occur by forming short‐circuits between adjacent circuit elements, or by forming open‐circuits in the conductors. The risk sites can be identified by type, and the total number enumerated by manual inspection of the photolithographic masks used to fabricate the printed circuit layers. However, the circuit density of high performance printed circuit boards has become so great that meaningful manual analysis has become impractical. A more effective method is to use special graphics programs to analyse the computer‐aided design (CAD) data. The methodology developed to perform the CAD analysis of high performance printed circuit boards for short‐circuits utilises two powerful computer graphic tools: the Interactive Graphics System and the Unified Shapes Checking system. Test data for open‐circuits are generated using specially written alphanumeric routines. The data can be used for stress testing the printed circuit boards by wiring up special test modules that are plugged into the boards and then placing the boards into environmental test chambers. The printed circuits are checked for short‐circuits by putting them into groups that have no risk of shorting to each other (zero risk), and placing the groups in parallel under an electrical potential. The flow of current between the groups would indicate a short‐circuit. Similarly, the printed circuits can be checked for open‐circuits, by stringing them together into groups in series, and measuring the changes in resistance under thermal stress. Both types of test data can also be used for in‐process testing.

Applications of Euclidean constructions to computer graphics

This paper presents an interactive graphics system called L.E.G.O. The purpose of L.E.G.O. is to model two- and three-dimensional objects using Euclidean geometry constructions. L.E.G.O. has a layered structure which makes it convenient to use, both for the experienced programmer and the novice. The programs may be written in a compiled language (C), written interactively in an interpreted language (LISP) or developed using a graphical interface in a multiple-window environment. Applications of L.E.G.O. include computer-assisted instruction of geometry and computer graphics, geometric modeling, and kinematic analysis. The use of imperative constructions and the powerful interface based on the idea of graphical programming are the most distinctive features of the system.

Linkage versus integration for binding data base and interactive graphics systems

A technique for binding data base and interactive graphics systems is presented and compared with other binding methods to indicate the essential differences and the corresponding trade-offs. Whereas the binding method that has been used in previous works is the integration of the graphics and data base systems through a specially designed interface, the method implemented here depends on establishing a linkage between these two systems using the file management module of the host operating system. The details of the linkage technique including the linkage mechanism, manipulation of both graphical and nongraphical data and the role of the operating system file manager are emphasized. A case study using a stock control example illustrates the implementation of the linkage method, binding a relational data base system and a computer-aided design graphics package. The example examines various operational conditions, including multilevel graphical structures.

A plate-kinematic framework for models of Caribbean evolution

We define the former relative positions and motions of the plates whose motions have controlled the geological evolution of the Caribbean region. Newly determined poles of rotation defining the approximate spreading histories of the central North and the South Atlantic oceans are given. For the late Jurassic-Early Cretaceous anomaly sequence of the central North Atlantic, we have used previously published ∗ ∗ Klitgord and Schouten (1987). definitions of fracture-zone traces and magnetic anomaly picks, redetermining the pole positions and angular rotations for various isochrons on an Evans and Sutherland interactive graphics system. For magnetic anomalies younger than the Cretaceous Quiet Period in both oceans, we (1) used Seasat altimeter data to help define fracture-zone traces, and (2) identified and used marine magnetic anomalies to determine the positions of spreading isochrons along the flowlines indicated by the fracture zones. By the finite difference method, the relative paleopositions and the relative motion history between North and South America were computed. This analysis defines the size and shape (and the rate at which the size and shape changed) of the interplate region between North and South America since the Middle Jurassic. Thus, a plate-kinematic framework is provided for the larger plates pertaining to the Caribbean region, in which can be derived more detailed scenarios for Gulf of Mexico and Caribbean evolution. North and South America diverged to approximately their present relative positions from Late Triassic? to Early Campanian (about 84 m.y. ago) time. This is the period during which the Gulf of Mexico and a Proto-Caribbean seaway were formed. Since the Campanian, only minor relative motion has occurred; from Early Campanian through to Middle Eocene times. South America diverged only another 200 km, and since the Middle Eocene, minor N-S convergence has occurred. These very minor post-Early Campanian motions have probably been accommodated by imperfect shear and compression along the Atlantic fracture zones to the east of the Lesser Antilles, and along the northern and southern borders of the Caribbean Plate. Accordingly, it is suggested that from Campanian time to the present, the relative motions between the North and South American plates have had only minor effects on the structural development of the Caribbean region. Primarily using the data of Engebretson et al. ∗∗ ∗∗ Engebretson (1982); Engebretson et al. (1985). , the convergence history of Pacific plates with North America was calculated for two points near the western Caribbean. By completing finite difference solutions, the convergence history of the Pacific plates with the Caribbean and South American plates can be approximated. The direction and rate of convergence of the Pacific plates with the Americas may have controlled the style of subduction and possible microplate migration along the North American, South American and western Caribbean boundaries that define the eastern Pacific plate margin.

GPROC—an integrated system for the processing of numerical scientific data

AbstractWork done on an interactive graphical processing system is described. An overview is given of the uses to which a system could be put, with especial reference to aspects of solid state physics. Algorithms which may be usefully included in such a system, when used in a technical scientific environment, are described. The problems of implementing such a system on small microcomputer systems are outlined, and some possible areas of future development are discussed.