Showing papers on "Line segment published in 1978"

Line segments are perceived better in a coherent context than alone: An object-line effect in visual perception

Abstract: In a series of four experiments, observers identified a briefly flashed line segment more accurately when it was part of a drawing that looked unitary and three-dimensional than when the line segment was presented alone. This extends earlier findings of better identification of a line segment when it is part of an apparently unitary, three-dimensional drawing than when it is in a less coherent flat design; and these results demonstrate a visua1 effect analogous to the word-letter effect which uses nonlinguistic materials. Experiment 1 demonstrates the existence of the object-line effect and shows that it does not depend on the presence of a subsequent mask; Experiment 2 shows that the effect holds up with two-altemative forcedchoice presentation; Experiment 3 demonstrates that the effect is not due to bright end points which may occur when the target line appears with a context; and Experiment 4 shows that the effect is as strong when the target line segments occupy widely separated spatial locations as it is when they occupy nearby, potentially confusable locations.

Apparatus for generating a raster image from line segments

Abstract: Apparatus for processing data whereby a digital control signal is generated for effecting the presentation of a selected portion of a map image on a raster display. The data includes stored data words describing characteristics of line segments utilizable to construct the image. The line segments include line vectors representative of elongated features of the image and boundary vectors identifying boundaries between image areas of different brightness. Processing of the data is accomplished by means of two control loops. The first control loop performs selected macrosteps including arithmetic manipulations, on the data words to effect generation of the digital control signal. The second control loop effects selection of the macrosteps to be performed by the first loop and routes the data words within the generator in response to the instant data being processed by the generator. In accordance with an additional feature of the invention, data words are generated for defining intersections to be displayed adjacent each intersection of a line segment with a raster line where the line segment has a slope of less than a predetermined magnitude. These additional intersections prevent the stepped appearance of line segments intersecting raster lines at small angles.

The Differential Effects of the Use of Manipulative Aids on the Learning of Geometric Concepts by Elementary School Children

Abstract: There is considerable support for the use of manipulative aids when teaching geometric concepts (Cheatham, 1969; Dienes & Golding, 1967; Yakimanskaya, 1971). However, the question of what aids to use and how to use them most effectively is unanswered. Wiviott's (1970) study suggests that concepts be presented to younger students in terms of the bases of classification they are able to use, that is, square, rectangle, rhombus, parallelogram, quadrilateral, triangle, circle, and cube. This research attempted to determine which instructional setting is most effective in teaching geometry to students at the third-grade level. The concepts (selected after examining the research by Dowell [1963] and Peck [1970]) included in this research were the following: point, line, line segment, triangle, square, pentagon, ray, angle, congruence of lines, congruence of angles, polygon, cube, tetrahedron, face, vertex, edge, diagonal, side, and endpoint.

Plate and line segment processes

Abstract: Random processes of diverse geomètric fígures have been studied in several papers in view of their applications. Coleman (1974), Parker and Cowan (1976) and more recently Berman (1977) are some of the authors who have solved several problems regarding this kind of process. In the fírst part of this paper we consider a random process of convex plates in R', computing the expected vàlues of certain random variables associated with such a process under a fairly general assumption of stationarity which is obviously satisfíed in the case of the strongly stationary Poisson process. The following section is devoted to line segment processes of the type considered by Parker and Cowan (1976). In this connection, we show how the formulas they State for the three-dimensíonal case, as well as those they derive for the plane, can be obtained from the now classical results of integral geometry as exposed, for example, in the work of Santaló (1936), (1976). In the last section, we consider a mixed process of plates and of line segments. By 'plates' we shall always understand convex plates.

Arabic numerical displays using segmented patterns

Abstract: The invention provides apparatus for visibly displaying Arabic numerals or symbols e.g. arithmetic symbols for use in devices such as calculators, digital clocks etc. The apparatus comprises a decoder adapted to convert an input signal (e.g. a BCD signal) representing a numeral or symbol in one system of numerals and symbols of the European System (as herein defined), to an output signal representing the corresponding Arabic language numeral or symbol, the output signal being used to illuminate or otherwise make visible a dot or a line segment of a 13, 14, 15 or 16 line segment display, preferably a liquid crystal display, to make visible the Arabic language numeral or symbol. For multiple digit numerals, an array of line segment displays is provided, the decoder being arranged to obey the rules in the Arabic language system concerning the location of arithmetic and quantity symbols with respect to the numeral when activating the various line segment displays.

Computer generation of symmetric, semisymmetric, antisymmetric, and asymmetric patterns

Abstract: A computer algorithm generates selected symmetric, semisymmetric, antisymmetric, and asymmetric patterns on a square field, using random number generation as the seed. All possible combinations of the geometric operations of 90-deg rotation and reflection have exactly equivalent operations on the “bytes” and “words” that make up the binary descriptions of the horizontal and vertical arrangements of visual information. Dot, checkerboard, oblique line, orthogonal line segment, and other more complex pattern types can be generated using this algorithm.

Light‐cone finite normal products

Abstract: A graphical subtraction procedure for constructing the perturbative Green functions of light‐cone finite, multiply localized products of fields is proposed The existence of the Green functions as tempered distributions is proved, together with the properties of light‐cone finiteness and localization on a line segment The derivation of light cone expansions is sketched, but not treated in detail