The Aesthetics of X-Junctions: Cognitive Constraints in the Art of Continuous-Line Caricature

Leonardo ◽  
2020 ◽  
Vol 53 (1) ◽  
pp. 81-82
Author(s):  
Kevin Burns
Keyword(s):  
Three Dimensional ◽  
Two Dimensional ◽  
Continuous Line ◽  
Line Segments ◽  
Cognitive Constraints ◽  
Individual Line

This article exposes cognitive constraints in production and perception of caricatures drawn with one continuous line. Constraints in production enable an artist to overcome the complexity of connecting all individual line segments of a conventional caricature. Constraints in perception enable an audience to overcome the complexity of inferring three-dimensional edges and shapes from two-dimensional line segments. In both production and perception, constraints exploit Xjunctions where the continuous line meets itself in crossing and tangent configurations that contribute to the aesthetics of these artworks.

FINDING SIMPLICES CONTAINING THE ORIGIN IN TWO AND THREE DIMENSIONS

2011 ◽  
Vol 21 (05) ◽  
pp. 495-506 ◽  
Author(s):  
KHALED ELBASSIONI ◽  
AMR ELMASRY ◽  
KAZUHISA MAKINO
Keyword(s):  
Three Dimensional ◽  
Three Dimensions ◽  
Dimensional Case ◽  
Two Dimensional ◽  
Line Segments

We show that finding the simplices containing a fixed given point among those defined on a set of n points can be done in O(n + k) time for the two-dimensional case, and in O(n2 + k) time for the three-dimensional case, where k is the number of these simplices. As a byproduct, we give an alternative (to the algorithm in Ref. 4) O(n log r) algorithm that finds the red-blue boundary for n bichromatic points on the line, where r is the size of this boundary. Another byproduct is an O(n2 + t) algorithm that finds the intersections of line segments having two red endpoints with those having two blue endpoints defined on a set of n bichromatic points in the plane, where t is the number of these intersections.

scholarly journals Diagnosis of Fetal Anomalies in Developing Country: Experiences in Indonesia

2007 ◽  
Vol 1 (1) ◽  
pp. 111-125
Author(s):  
Azen Salim ◽  
Gulardi Hanifa Wiknjosastro ◽  
I Gede Putu Surya ◽  
Bambang Karsono ◽  
I Made Kornia Karkata ◽  
...  
Keyword(s):  
Clinical Practice ◽  
Developing Country ◽  
Three Dimensional ◽  
Routine Clinical Practice ◽  
Two Dimensional ◽  
Continuous Line ◽  
Fetal Anomalies ◽  
Fetal Abnormalities ◽  
Publishing Article

Abstract Although three-dimensional ultrasound (3DUS) has been available for more than 10 years in Indonesia, there was no publishing article from our region which systematically evaluates our experiences in this most recent ultrasound technologies and its application to obstetric. 3DUS is revolving into a technology with various range of applications in numerous fields because it helps overcome some of the key limitations related to two-dimensional imaging. It is through this review that we attempt to develop a continuous line of understanding the current diagnostic benefits of 3D and 4DUS in diagnosis of fetal abnormalities and consider the utility and role of this type of imaging in the routine clinical practice.

Three-Dimensional Perception of Planar Line Segments

Perception ◽  
1979 ◽  
Vol 8 (4) ◽  
pp. 381-388
Author(s):  
Horst W Hoyer
Keyword(s):  
Short Distance ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Line Segments ◽  
Planar Line ◽  
Line Drawings ◽  
Parallel Lines ◽  
Three Dimensional Images

Two-dimensional line drawings can be perceived as three-dimensional images if they are viewed through a grating of parallel lines placed a short distance above the drawing. The position in space of the images is a function of the angle between the lines in the drawing and those in the viewer grating.

A Region-Based Stereo

1996 ◽  
Vol 8 (2) ◽  
pp. 171-176
Author(s):  
Hiroshi Katsulai ◽  
◽  
Hirotaka Niwa
Keyword(s):  
Three Dimensional ◽  
Depth Information ◽  
Central Projection ◽  
Two Dimensional ◽  
Region Segmentation ◽  
Line Segments ◽  
Projected Image ◽  
Regional Features ◽  
Basic Studies ◽  
Dimensional Object

The stereo, which is a method of obtaining depth information of scene from images obtained from at least two different directions, plays a very important role in applications to robots and similar equipments. The most difficult task in stereo method is to match individual parts of a two-dimensional projected image to those of another image.1,2) With respect to the method of matching, many studies have been conducted, and various techniques have been proposed. The stereo method based on features has attracted attention in recent years. However, it often fails in matching parts when attempting matching using points as features3) because it is difficult to specify points in images. On the other hand, proposals have been made for using line segments, which are easier than points to extract, as opposed to points for matching individual parts.6) Furthermore, methods have been developed which use regional features as an extension of the method which uses line segments.7) The method that uses regional features is considered to have a higher probability of success in matching images than the methods that use points or straight line segments because regional features contain a relatively large amount of description. However, no sufficient studies have been made yet on the region-based stereo. This study situation makes it necessary to conduct basic studies on regionbased stereo. This paper employs regions as features for matching, describes the stereo algorithm that directly employs region segmentation, and investigates the appropriateness of the algorithm by means of computer simulations. It is assumed that the three-dimensional object is a polyhedron, and each face of the object is projected onto a two-dimensional projection plane with uniform brightness using central projection. Region segmentation is delicate and does not necessarily ensure stable results. However, it is considered that a pair of two-dimensional projected images does not contain very large differences if the same scene is to be observed from slightly different directions. This paper uses the centroid of region, which represents the position of region, region shape, and the gray level of region as features for matching. Some consideration is taken on the matching technique to increase the accuracy of matching by performing an operation that is almost equal to enumerating all regional elements, using the sum of the similarity values of regional features as the evaluation function. A three-dimensional plane can be calculated from two matching regions by matching the two boundary points at the same height in the two projected images.

High Resolution Microscopy of Multi-Layered Biological Crystals

1982 ◽  
Vol 40 ◽  
pp. 80-83
Author(s):  
H.A. Cohen ◽  
T.W. Jeng ◽  
W. Chiu
Keyword(s):  
High Resolution ◽  
Low Dose ◽  
Three Dimensional ◽  
Data Interpretation ◽  
Two Dimensional ◽  
Biological Objects ◽  
Density Maps ◽  
Density Map ◽  
Complex Crystal ◽  
High Resolution Microscopy

This tutorial will discuss the methodology of low dose electron diffraction and imaging of crystalline biological objects, the problems of data interpretation for two-dimensional projected density maps of glucose embedded protein crystals, the factors to be considered in combining tilt data from three-dimensional crystals, and finally, the prospects of achieving a high resolution three-dimensional density map of a biological crystal. This methodology will be illustrated using two proteins under investigation in our laboratory, the T4 DNA helix destabilizing protein gp32*I and the crotoxin complex crystal.

Instrumentation For Quantitative Microscopy

1977 ◽  
Vol 35 ◽  
pp. 206-209
Author(s):  
B. Ralph ◽  
A.R. Jones
Keyword(s):  
Volume Fraction ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Automatic Data ◽  
Phase Volume Fraction ◽  
Statistical Confidence ◽  
Resultant Data ◽  
Automatic Data Collection ◽  
Third Dimension ◽  
Evolution Of Microstructure

In all fields of microscopy there is an increasing interest in the quantification of microstructure. This interest may stem from a desire to establish quality control parameters or may have a more fundamental requirement involving the derivation of parameters which partially or completely define the three dimensional nature of the microstructure. This latter categorey of study may arise from an interest in the evolution of microstructure or from a desire to generate detailed property/microstructure relationships. In the more fundamental studies some convolution of two-dimensional data into the third dimension (stereological analysis) will be necessary.In some cases the two-dimensional data may be acquired relatively easily without recourse to automatic data collection and further, it may prove possible to perform the data reduction and analysis relatively easily. In such cases the only recourse to machines may well be in establishing the statistical confidence of the resultant data. Such relatively straightforward studies tend to result from acquiring data on the whole assemblage of features making up the microstructure. In this field data mode, when parameters such as phase volume fraction, mean size etc. are sought, the main case for resorting to automation is in order to perform repetitive analyses since each analysis is relatively easily performed.

A linearity test for thick specimens imaged by HVEM over a 180° angular range

1991 ◽  
Vol 49 ◽  
pp. 552-553
Author(s):  
Yu Liu
Keyword(s):  
Phase Contrast ◽  
Three Dimensional ◽  
Angular Range ◽  
Two Dimensional ◽  
Back Projection ◽  
Line Integral ◽  
Exponential Law ◽  
Transmission Electron ◽  
Absorption Law ◽  
Linearity Test

The image obtained in a transmission electron microscope is the two-dimensional projection of a three-dimensional (3D) object. The 3D reconstruction of the object can be calculated from a series of projections by back-projection, but this algorithm assumes that the image is linearly related to a line integral of the object function. However, there are two kinds of contrast in electron microscopy, scattering and phase contrast, of which only the latter is linear with the optical density (OD) in the micrograph. Therefore the OD can be used as a measure of the projection only for thin specimens where phase contrast dominates the image. For thick specimens, where scattering contrast predominates, an exponential absorption law holds, and a logarithm of OD must be used. However, for large thicknesses, the simple exponential law might break down due to multiple and inelastic scattering.

An Image Reconstruction System Applied to High Voltage Microscopy

1975 ◽  
Vol 33 ◽  
pp. 292-293
Author(s):  
D. E. Johnson
Keyword(s):  
High Voltage ◽  
Prior Information ◽  
Block Diagram ◽  
Three Dimensional ◽  
Real Space ◽  
Two Dimensional ◽  
Efficient Manner ◽  
Fourier Methods ◽  
Tilt Series ◽  
Methods Of Reconstruction

Increased specimen penetration; the principle advantage of high voltage microscopy, is accompanied by an increased need to utilize information on three dimensional specimen structure available in the form of two dimensional projections (i.e. micrographs). We are engaged in a program to develop methods which allow the maximum use of information contained in a through tilt series of micrographs to determine three dimensional speciman structure.In general, we are dealing with structures lacking in symmetry and with projections available from only a limited span of angles (±60°). For these reasons, we must make maximum use of any prior information available about the specimen. To do this in the most efficient manner, we have concentrated on iterative, real space methods rather than Fourier methods of reconstruction. The particular iterative algorithm we have developed is given in detail in ref. 3. A block diagram of the complete reconstruction system is shown in fig. 1.

Computer Assisted Image Reconstruction of Oligomer Structure

1976 ◽  
Vol 34 ◽  
pp. 472-473
Author(s):  
A.M. Jones ◽  
A. Max Fiskin
Keyword(s):  
Three Dimensional ◽  
Depth Of Field ◽  
Computer Assisted ◽  
Projection Data ◽  
Two Dimensional ◽  
Single Particles ◽  
Dimensional Reconstruction ◽  
Computer Assisted Image ◽  
The Fourier Transform ◽  
Space Approach

If the tilt of a specimen can be varied either by the strategy of observing identical particles orientated randomly or by use of a eucentric goniometer stage, three dimensional reconstruction procedures are available (l). If the specimens, such as small protein aggregates, lack periodicity, direct space methods compete favorably in ease of implementation with reconstruction by the Fourier (transform) space approach (2). Regardless of method, reconstruction is possible because useful specimen thicknesses are always much less than the depth of field in an electron microscope. Thus electron images record the amount of stain in columns of the object normal to the recording plates. For single particles, practical considerations dictate that the specimen be tilted precisely about a single axis. In so doing a reconstructed image is achieved serially from two-dimensional sections which in turn are generated by a series of back-to-front lines of projection data.

Polymorphic phase transition of a membrane protein - analysis of continuous diffuse electron diffraction intensity

1986 ◽  
Vol 44 ◽  
pp. 166-167
Author(s):  
Douglas L. Dorset ◽  
Andrew K. Massalski
Keyword(s):  
Molecular Sieve ◽  
Three Dimensional ◽  
Pore Geometry ◽  
Two Dimensional ◽  
Diffraction Intensity ◽  
Polymorphic Phase Transition ◽  
E Coli ◽  
Crystallographic Study ◽  
Hexagonal Form ◽  
Polymorphic Forms

Matrix porin, the ompF gene product of E. coli, has been the object of a electron crystallographic study of its pore geometry in an attempt to understand its function as a membrane molecular sieve. Three polymorphic forms have been found for two-dimensional crystals reconstituted in phospholipid, two hexagonal forms with different lipid content and an orthorhombic form coexisting with and similar to the hexagonal form found after lipid loss. In projection these have been shown to retain the same three-fold pore triplet geometry and analyses of three-dimensional data reveal that the small hexagonal and orthorhombic polymorphs have similar structure as well as unit cell spacings.

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