On the Localization of Straight Lines in 3D Space from Single 2D Images

There is a widespread belief in art praxis that linear perspective is only a geometric approximation to the ‘true’ properties of perspective as experienced in the perception of the world, which are thought to involve some form of curvilinear perspective. The origins of that belief are examined from Roman times to the present, with a focus on the generation of perspective curvature by the active viewer as a means of elucidating the underlying perceptual principles involved. It is concluded that the only valid form of perspective for the flat canvas is linear perspective, and that it is valid only for a viewing location at the geometric center of projection for which the picture was constructed. Viewing from any other location (particularly in the case of wide-field images viewed from greater than the required distance) generates perceived distortions that have often been misinterpreted to imply that linear perspective geometry is inadequate and that some form of curvilinear perspective would be more representative. However, as long as it is viewed with one eye from the center of projection, the perceptual experience of accurate linear perspective is of a full, explorable 3D space, in contrast to any other form of perspective convention.

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Spatial Analysis of 3D Space using 2D Images

SSRN Electronic Journal ◽

10.2139/ssrn.3586882 ◽

2020 ◽

Author(s):

Annie Benjamin ◽

Pradhumn Kanase ◽

Maitreyee Likhite ◽

Noella Noronha ◽

Anita Jadhav

Keyword(s):

Spatial Analysis ◽

3D Space ◽

2D Images

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Human Segmentation and Tracking Survey on Masks for MADS Dataset

Sensors ◽

10.3390/s21248397 ◽

2021 ◽

Vol 21 (24) ◽

pp. 8397

Author(s):

Van-Hung Le ◽

Rafal Scherer

Keyword(s):

Source Code ◽

Human Detection ◽

Human Tracking ◽

Person Detection ◽

Human Segmentation ◽

3D Space ◽

Human Pose ◽

Complex Activities ◽

2D Images ◽

Segmentation And Tracking

Human segmentation and tracking often use the outcome of person detection in the video. Thus, the results of segmentation and tracking depend heavily on human detection results in the video. With the advent of Convolutional Neural Networks (CNNs), there are excellent results in this field. Segmentation and tracking of the person in the video have significant applications in monitoring and estimating human pose in 2D images and 3D space. In this paper, we performed a survey of many studies, methods, datasets, and results for human segmentation and tracking in video. We also touch upon detecting persons as it affects the results of human segmentation and human tracking. The survey is performed in great detail up to source code paths. The MADS (Martial Arts, Dancing and Sports) dataset comprises fast and complex activities. It has been published for the task of estimating human posture. However, before determining the human pose, the person needs to be detected as a segment in the video. Moreover, in the paper, we publish a mask dataset to evaluate the segmentation and tracking of people in the video. In our MASK MADS dataset, we have prepared 28 k mask images. We also evaluated the MADS dataset for segmenting and tracking people in the video with many recently published CNNs methods.

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Knowledge Based System for Visual Computing of Depth in 2D Images of Geometric Objects Like Straight Lines, Planes and Solids and their Applications in Engineering Graphics

Journal of Computer Science ◽

10.3844/jcssp.2006.612.614 ◽

2006 ◽

Vol 2 (8) ◽

pp. 612-614 ◽

Cited By ~ 1

Author(s):

M. Narayana Rao ◽

V. VaithyaNat

Keyword(s):

Engineering Graphics ◽

Knowledge Based System ◽

Knowledge Based ◽

Visual Computing ◽

Geometric Objects ◽

Straight Lines ◽

2D Images

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Geometric Constraints of Visual Space

i-Perception ◽

10.1177/20416695211055212 ◽

2021 ◽

Vol 12 (6) ◽

pp. 204166952110552

Author(s):

Casper J. Erkelens

Keyword(s):

Free Parameter ◽

Physical Space ◽

Visual Space ◽

Geometric Constraints ◽

Vanishing Point ◽

Geometric Features ◽

Space Model ◽

3D Space ◽

Parallel Lines ◽

Straight Lines

Perspective space has been introduced as a computational model of visual space. The model is based on geometric features of visual space. The model has proven to describe a range of phenomena related to the visual perception of distance and size. Until now, the model lacks a mathematical description that holds for complete 3D space. Starting from a previously derived equation for perceived distance in the viewing direction, the suitability of various functions is analyzed. Functions must fulfill the requirement that straight lines, oriented in whatever direction in physical space, transfer to straight lines in visual space. A second requirement is that parallel lines oriented in depth in physical space, converge to a finite vanishing point in visual space. A rational function for perceived distance, compatible with the perspective-space model of visual space, satisfies the requirements. The function is unique. Analysis of alternative functions shows there is little tolerance for deviations. Conservation of the straightness of lines constrains visual space to having a single geometry. Visual space is described by an analytical function having one free parameter, that is, the distance of the vanishing point.

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Domain Formation in Synthetic Quartz

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100064839 ◽

1971 ◽

Vol 29 ◽

pp. 156-157

Author(s):

Joseph J. Comer

Keyword(s):

Electron Beam ◽

Room Temperature ◽

Domain Formation ◽

Synthetic Quartz ◽

Transmission Electron ◽

Black Spots ◽

Diffraction Mode ◽

Domain Boundaries ◽

Kikuchi Lines ◽

Straight Lines

Domains visible by transmission electron microscopy, believed to be Dauphiné inversion twins, were found in some specimens of synthetic quartz heated to 680°C and cooled to room temperature. With the electron beam close to parallel to the [0001] direction the domain boundaries appeared as straight lines normal to <100> and <410> or <510> directions. In the selected area diffraction mode, a shift of the Kikuchi lines was observed when the electron beam was made to traverse the specimen across a boundary. This shift indicates a change in orientation which accounts for the visibility of the domain by diffraction contrast when the specimen is tilted. Upon exposure to a 100 KV electron beam with a flux of 5x 1018 electrons/cm2sec the boundaries are rapidly decorated by radiation damage centers appearing as black spots. Similar crystallographio boundaries were sometimes found in unannealed (0001) quartz damaged by electrons.

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