Affine transformations for digitized spatial data in geology

Affine transformations are among the most basic and useful geometrical operations in computer applications in geology. Homogeneous coordinates extend their applicability. The methods are essential in handling digitized locational data and are applicable widely in other graphical applications such as calibrating data sets for plotting, and in shape comparison and spatial analysis. Affine transformations alter the length of lines and the angles between them, whereas straight lines remain straight, parallel lines remain parallel, and the ratio in which a point divides a line remains the same.Their geometrical significance indicates that they can be visualized readily, and the corresponding operations in matrix algebra provide a straightforward method of computer implementation. A transformation matrix is calculated from four calibration points, the coordinates of which are known before and after transformation. Multiplication of coordinates in the initial frame of reference by the transformation matrix converts them to coordinates in the new frame of reference. A listing of relevant FORTRAN programs is given, with examples.     

ISO: A Fortran IV Program for Generating Isopleth maps on Small Computers

The construction of computer-generated isopleth maps has been limited generally to large computer programs such as SYMAP and AUTOMAP II. These programs may require machines with large amounts of memory. Large machines are not available to many potential users. This paper describes the program ISO, which is designed to create isopleth maps on small- and medium-size computers. ISO complements the CMAP program developed to produce chloropleth maps on small computers and employs many of the features used in CMAP. It also provides some additional features such as limited map cosmetic capability, internal storage of scan lines for multiple map runs, and greater operational convenience in establishing map categories, symbols, and text. Proximal maps also can be generated by ISO.     

A computer method of constructing geological histories from field surveys and maps

A computer method has been designed to analyze binary relations between geological events. It interprets the relations in a form which allows construction of a multinodal network of relationships (of which tree-form networks are a special situation).The method is a form of data management which does not require the names to be ranked or the relations between names to be specified in advance, as do other geological systems. The data within the file may be added to as new information is collected, and the relationships determined from the data on file at any time. The method therefore is suited particularly to studies in which data accumulate progressively. Data structures which are more complex than a multinodal network are detected as “contradictions” or “contradictory rings”.The method has been used successfully in constructing explanations for geological maps from the field evidence recorded on the face of the map. It provides a means of assembling historical data from many maps as well as from supplementary information, such as radiometric or paleontological dates, and synthesizing a history for a region. The method therefore may be useful in tectonic analysis.     

The FASTRAK automatic digitising system

The FASTRAK system is an interactive line-following digitiser, scanning a reduction of a map with a laser beam. The track-following software operates by analysing the data from local raster scans into line elements and then assembling these elements into complete lines. The software is interactive and is entirely command driven, thus providing a powerful and flexible system. This paper discusses the hardware and software used, and gives performance figures for two sample maps.     

Distributed data bases

Distributed data bases provide a means for storing, managing and accessing large volumes of structured data. This technology is coupled with current developments in distributed systems. This paper references a distributed system under development by the Surveys and Mapping Branch of the Department of Energy, Mines and Resources in Canada, for the production of faired drawings from a geographic data base. Some of the notions and considerations involved in the development of distributed data bases also are discussed.     

G-plot: graphics in the geological computer

G-PLOT is a package of programs for graphic display of data. It has been designed as an integral part of the G-EXEC data-handling system, and adopts the principles of G-EXEC: it is generalized with respect to data, it is structured and modular, and it has a simple (near-English) user interface. In addition, a number of standards have been defined to allow the greatest possible flexibility of usage of the programs, as well as to provide a consistent and powerful set of modules for the applications programmer. The two most significant of these standards are the use of the ‘plot-frame’ concept and the definition of logical raster levels between the data and a ‘logical plotter’. By the use of these standards, it is possible not only to send generated plots to any available graphic device, but also to edit plots by selection and manipulation of logical ‘subframes’—units of plot data such as axes, titling, map frames, and grids. By the combination of G-PLOT facilities with planned enhancements to the G-EXEC system, it will be possible to generate sequences of plot frames from iterative simulation models, or from successively changing parameters (scaling or rotation for example) in normal application programs.     

Orthogonal mapping: A computer program for quantifying shape differences

Quantitative differences in the shape of two or more objects can be obtained by Orthogonal Mapping provided coincidental or analogous points can be identified on each object. The least-squares difference between each set of analogous points is determined by use of a projective transformation of a set of measured points which involves the rotation, translocation, and scaling of these points relative to a set of fixed points.     

A computer system for interpreting blood glucose data

This paper presents an overview on the design and implementation of a computer system for the interpretation of home monitoring data of diabetic patients. The comprehensive methodology covers the major information processing steps leading from raw data to a concise summary of what has happened between two subsequent visits. It includes techniques for summarising and interpreting data, checking for inconsistency, identifying and diagnosing metabolic problems and learning from patient data. Data interpretation focuses on extracting trend patterns and classifying/clustering daily blood glucose (BG) profiles. The software helps clinicians to explore data recorded before the main meals and bedtime, and to identify problems in the patient's metabolic control which should be addressed either by educating the patient and/or adjusting the current management regimen.     

Extraction and recognition of geographical features from paper maps

With the emergence of Geographical Information Systems (GIS), map acquisition and recognition have become hotly pursued topics, both by the industry and the academia. The paper presents a novel methodology for the extraction and recognition of symbol features from topographic maps. The method proceeds by separating the map into its constituent layers and then attempting to recognize the features in different layers on the basis of symbol-specific geometrical and morphological attributes. Text strings have also been separated. The output is obtained in the form of an ‘e-map’ that is vectorized and hence is suitable for GIS. To demonstrate the usefulness of the proposed system a simple database along with a query processing facility is constructed integrating the information obtained from the e-map and ‘some’ user inputs. The methodology has been observed to perform quite satisfactorily.     

Executive system concept for processing geological data

Computer analysis of most geological problems requires several analytical or manipulative steps on one or more data sets. Each problem may have a unique sequence of these steps, although there typically will be a general examination and editing of data, a few transformations, and finally, several types of analyses. Because each of the data edit and transformation steps result in newly altered data sets, some of which are only intermediate results, problem-solving time can be reduced by letting a program keep track of these results. In addition, if the program is designed to perform several different types of operations in a user-specified order, the number of separate computer jobs can be reduced.An Executive system is a series of subprograms that are controlled by a “driver,” a special subroutine that can recognize task keywords and then direct control to the appropriate subprograms for analysis. The steps required to write an Executive program include: (1) definition of task-identification keywords, (2) implementation of a branching control structure to reach appropriate subprograms, and (3) construction of data handling subroutines and the definition of data formats recognized by these routines. The concepts are illustrated with examples from a statistical analysis system.     

A general purpose computer analysis system for chromatographic data

A manual integration system for the analysis of chromatographic data is described. The analog output produced by an HPLC absorbance monitor is passed to a non-inverting signal amplifier. This amplified signal is sent to an IBM PC where an analog to digital converter is used to digitize the data. A set of six computer programs which collect, store and analyze these data are presented. This system was used to analyze the nucleotide content of the anaerobic organism Clostridium acetobutylicum by strong anion-exchange HPLC.     

A hybrid GRASP heuristic to construct effective drawings of proportional symbol maps

Proportional symbol map is a cartographic tool that employs symbols to represent data associated with specific locations. Each symbol is drawn at the location of an event and its size is proportional to the numerical data collected at that point on the map. The symbols considered here are opaque disks. When two or more disks overlap, part of their boundaries may not be visible and it might be difficult to gauge their size. Therefore, the order in which the disks are drawn affects the visual quality of a map. In this work, we focus on stacking drawings, i.e., a drawing that corresponds to the disks being stacked up, in sequence, starting from the one at the bottom of the stack. We address the Max-Total problem, which consists in maximizing the total visible boundary of all disks. We propose a sophisticated heuristic based on GRASP that includes most of the advanced techniques described in the literature for this procedure. We tested both sequential and parallel implementations on benchmark instances and the comparison against optimal solutions confirms the high quality of our heuristic. To the best of our knowledge, this is the first time a metaheuristic is applied to this problem.     

Low cost computer graphics for micro computers

A graphical output system small enough to fit on a medium range micro computer is described. The system, called Outline, allows the user to produce line drawings in an infinite two dimensional space. It also offers a picture building facility in which the relationship between different sub-pictures is specified by mathematical transformations. A basic set of picture manipulating facilities along with a set of physical drawing attributes for each device is defined. The system is embedded in a high level language for simplicity of use.     

New methodologies for geological surveys

Within the context of Quaternary geology, current developments in the automation of survey data aim at mechanization of traditional data-handling techniques. In this type of automation, computer systems are asked to perform tasks at which they are slow, clumsy, and expensive. The need for continuous human support makes conventional automation unattractive.Traditional geological survey methodology has developed within the framework of manual data-handling techniques. The sampling design, data compression and generalization, the stratigraphic map all illustrate our inability to return to the only hard facts available: the observed boreholes and outcrops and their attributes.The computer can liberate us from most of these constraints. New sampling designs will be based on recent work in geostatistics. Information from existing archives may be captured through free-language processing, new borelogs will be recorded directly on magnetic medium. Lithological and stratigraphic interpretation will be automated and rely on numerical classification techniques. Traditional map drawing will disappear, the general purpose map will be replaced by special purpose univariate and multivariate maps computed directly from borelogs, but influenced by subjective point, line and area data.Experiments with the Quaternary by the Dutch geological survey are used to illustrate the feasibility of this alternative automation. The steps Input (free-language processing), Stratigraphic identification (interactive allocation), and Map construction (multivariate automated mapping) are illustrated.     

A package of computer programs for handling taxonomic databases

A package of programs is described which processes taxonomic data, suitable to use when preparing monographs, handbooks, Floras or Faunas, in which species or other taxa are described and identified. There is also an interactive program for specimen identification, and conversion routines which prepare data for numerical taxonomy (clustering and cladistics). The programs are equally suitable for botany or for zoology, or even for non-biological data.     

A SKOS-based multilingual thesaurus of geological time scale for interoperability of online geological maps

The usefulness of online geological maps is hindered by linguistic barriers. Multilingual geoscience thesauri alleviate linguistic barriers of geological maps. However, the benefits of multilingual geoscience thesauri for online geological maps are less studied. In this regard, we developed a multilingual thesaurus of geological time scale (GTS) to alleviate linguistic barriers of GTS records among online geological maps. We extended the Simple Knowledge Organization System (SKOS) model to represent the ordinal hierarchical structure of GTS terms. We collected GTS terms in seven languages and encoded them into a thesaurus by using the extended SKOS model. We implemented methods of characteristic-oriented term retrieval in JavaScript programs for accessing Web Map Services (WMS), recognizing GTS terms, and making translations. With the developed thesaurus and programs, we set up a pilot system to test recognitions and translations of GTS terms in online geological maps. Results of this pilot system proved the accuracy of the developed thesaurus and the functionality of the developed programs. Therefore, with proper deployments, SKOS-based multilingual geoscience thesauri can be functional for alleviating linguistic barriers among online geological maps and, thus, improving their interoperability.     

A method for drawing slope maps from contour maps by automatic data acquisition and processing

A method for drawing slope (angle) maps is described. After the contour lines of a topographic map have been expressed in digital form by a digitizer, the ground surface is considered as a set of partly overlapping trend surfaces. Slope values then are calculated at the mesh points of a grid superimposed on each of these mathematically expressed surfaces. The final map consists of a set of isolines (isoclines) obtained by slope values interpolation. The computer is used to determine the slope values, whereas the final map is obtained by a plotter.