An improved line-of-sight method for visibility analysis in 3D complex landscapes

<p><strong>Abstract.</strong> Visibility is a common measure to describe the spatial properties of an environment related to the spatial behaviour. Isovists represent the space that can be seen from one observation point, and they are used to analyse the existence of obstacles affecting or blocking intervisibility in an area. Although point clouds depict the as-built reality in a very detailed and accurate way, literature addressing the analysis of visibility in 3D, and more specifically the usage of point clouds to visibility analysis, is rather limited. In this paper, a methodology to evaluate visibility from point clouds in indoor environments is proposed, resulting in the creation of 3D isovists. Point cloud is firstly discretized in a voxel-based structure and voxels are labelled into ‘exterior’, ‘occupied’, ‘visible’ and ‘occluded’ based on an occupancy followed by a visibility analysis performed from a ray-tracing algorithm. 3D Isovists are created from the boundary of visible voxels from an observer position and considering as input parameters the visual angle, maximum line of sight, and eye gaze direction.</p>

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Integrating ‘weighted views’ to quantitative 3D visibility analysis as a predictive tool for perception of space

Environment and Planning B Urban Analytics and City Science ◽

10.1177/0265813516676486 ◽

2016 ◽

Vol 45 (2) ◽

pp. 345-366 ◽

Cited By ~ 3

Author(s):

Dafna Fisher-Gewirtzman

Keyword(s):

Relative Weight ◽

Human Perception ◽

Urban Environments ◽

Line Of Sight ◽

Relative Impact ◽

Predictive Tool ◽

Visibility Analysis ◽

Design Processes ◽

Planning And Design ◽

The Impact

The ability to predict the human perception of space in dense urban environments would have a vast impact on planning and design processes. Many analytical models, methods and tools have been developed to describe and predict human perception and behaviour in the urban environment, and academic papers have addressed the issue of the view in urban environments as a significant variant influencing perception and quality of life. In the present paper, we introduce the integration of weighted views (the relative impact of a view on a viewer) in a 3D Line of Sight visibility analysis as a predictive tool for perceptions of space focusing on ‘perceived density’. The integration of subjective qualitative information with objective measurements of the volume of visible space may bring evaluations closer to human perceptions of space. The research background consists of state-of-the-art visibility analysis and research concerned with the impact of the view on perceptions of space. An experiment in a visualization laboratory explored the relative impact of various views on the ‘perceived density’ and ‘visual privacy’ of 100 participants. The relative weight of each view presented to the subjects was based on the statistical results of the experiment. The weights were integrated into the 3D Line of Sight visibility analysis and the model is applied in a case study. The integrated 3D Line of Sight visibility analysis currently runs with off-the-shelf software available to all practicing architects and planners. It is expected that in the near future, the tool developed in this work will become an important aid to all practitioners, the method becoming a valuable evaluation tool in planning and design processes. Considering design alternatives, it may become a stepping stone for design principles and regulations.

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An Improved LOS Method for Implementing Visibility Analysis of 3D Complex Landscapes

2008 International Conference on Computer Science and Software Engineering ◽

10.1109/csse.2008.1157 ◽

2008 ◽

Cited By ~ 3

Author(s):

Liu Liu ◽

Liqiang Zhang ◽

Chen Chen ◽

Hong Chen

Keyword(s):

Visibility Analysis ◽

Complex Landscapes

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Variation of the amount of hydrogen along the galactic ridge

Symposium - International Astronomical Union ◽

10.1017/s0074180900100889 ◽

1967 ◽

Vol 31 ◽

pp. 171-172

Author(s):

Th. Schmidt-Kaler

Keyword(s):

Surface Brightness ◽

Milky Way ◽

Neutral Hydrogen ◽

Line Of Sight ◽

Optical Surface ◽

Hydrogen Density ◽

Continuous Radiation ◽

Galactic Longitude

The integralNHof neutral-hydrogen density along the line of sight is determined from the Kootwijk and Sydney surveys. The run ofNHwith galactic longitude agrees well with that of thermal continuous radiation and that of the optical surface brightness of the Milky Way.

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Structuring, Motions and Shapes of Corona Emission Line Profiles

International Astronomical Union Colloquium ◽

10.1017/s0252921100025720 ◽

1994 ◽

Vol 144 ◽

pp. 421-426

Author(s):

N. F. Tyagun

Keyword(s):

Emission Line ◽

Filling Factor ◽

Direct Relationship ◽

Coronal Plasma ◽

Line Of Sight ◽

Line Profiles ◽

The Difference ◽

Yellow Line ◽

Red Line

AbstractThe interrelationship of half-widths and intensities for the red, green and yellow lines is considered. This is a direct relationship for the green and yellow line and an inverse one for the red line. The difference in the relationships of half-widths and intensities for different lines appears to be due to substantially dissimilar structuring and to a set of line-of-sight motions in ”hot“ and ”cold“ corona regions.When diagnosing the coronal plasma, one cannot neglect the filling factor - each line has such a factor of its own.

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