Scalable visibility color map construction in spatial databases

Choudhury, Farhana Murtaza; Ali, Mohammed Eunus; Masud, Sarah; Nath, Suman; Rabban, Ishat E

doi:10.1016/j.is.2013.12.002

Cited by 9 publications

(12 citation statements)

References 29 publications

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“…al. [1]. But they do not handle the case of partial visibility and their solution is not applicable for a moving target as we outline in the introduction.…”

Section: Visibility In Spatial Queriesmentioning

confidence: 99%

“…We formally define the VCM as follows: In an earlier attempt [1] to construct the VCM for a fixed target, a point gets a nonzero color if the target is entirely visible from that point. However, the target can be partially visible from a point because of obstruction by the obstacles.…”

Section: Problem Formulationmentioning

confidence: 99%

“…In a recent work [1], Choudhury et al proposed a technique to compute a VCM for a fixed target. Two major limitations of this technique are as follows: (i) They do not take the partial visibility into account, i.e., a viewpoint is simply discarded (i.e., considered as non-visible) if an obstacle even slightly blocks the view of the target from that viewpoint.…”

Section: Introductionmentioning

confidence: 99%

“…First, since the proposed technique in [1] uses simple tangents between extreme points of an obstacle and the target, it cannot be converted to assess the partial visibility while computing the VCM. In this paper, we take the partial visibility into account, which is the correct form of the VCM for a fixed target and is a much harder problem with wider acceptability than [1]. Second, if the position of the target changes, the entire VCM needs to be reconstructed as the proposed data structure in [1] does not support incremental updates of the VCM.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we take the partial visibility into account, which is the correct form of the VCM for a fixed target and is a much harder problem with wider acceptability than [1]. Second, if the position of the target changes, the entire VCM needs to be reconstructed as the proposed data structure in [1] does not support incremental updates of the VCM.…”

Section: Introductionmentioning

confidence: 99%

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Visibility Color Map for a Fixed or Moving Target in Spatial Databases

Rabban

Abdullah

Ali

et al. 2015

Advances in Spatial and Temporal Databases

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Abstract. The widespread availability of 3D city models enables us to answer a wide range of spatial visibility queries in the presence of obstacles (e.g., buildings). Example queries include "what is the best position for placing a billboard in a city?" or "which hotel gives the best view of the city skyline?". These queries require computing and differentiating the visibility of a target object from each viewpoint of the surrounding space. A recent approach models the visibility of a fixed target object from the surrounding area with a visibility color map (VCM ), where each point in the space is assigned a color value denoting the visibility measure of the target. In the proposed VCM, a viewpoint is simply discarded (i.e., considered as non-visible) if an obstacle even slightly blocks the view of the target from the viewpoint, which restricts its applicability for a wide range of applications. To alleviate this limitation, in this paper, we propose a scalable, efficient and comprehensive solution to construct a VCM for a fixed target that considers the partial visibility of the target from viewpoints. More importantly, our proposed data structures for the fixed target support incremental updates of the VCM if the target moves to near-by positions. Our experimental results show that our approach is orders of magnitude faster than the straightforward approach.

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“…al. [1]. But they do not handle the case of partial visibility and their solution is not applicable for a moving target as we outline in the introduction.…”

Section: Visibility In Spatial Queriesmentioning

confidence: 99%

Section: Problem Formulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Visibility Color Map for a Fixed or Moving Target in Spatial Databases

Rabban

Abdullah

Ali

et al. 2015

Advances in Spatial and Temporal Databases

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Continuous Maximum Visibility Query for a Moving Target

Haider

Arman

Ali

et al. 2016

Lecture Notes in Computer Science

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Opportunities to answer many real life queries such as "which surveillance camera has the best view of a moving car in the presence of obstacles?" have become a reality due to the development of location based services and recent advances in 3D modeling of urban environments. In this paper, we investigate the problem of continuously finding the best viewpoint from a set of candidate viewpoints that provides the best view of a moving target in presence of visual obstacles in 2D or 3D space. We propose a query type called k Continuous Maximum Visibility (kCMV) query that ranks k query viewpoints (or locations) from a set of candidate viewpoints in the increasing order of the visibility measure of the target from these viewpoints. We propose two approaches that reduce the set of query locations and obstacles to consider during visibility computation and efficiently update the results as target moves. We conduct extensive experiments to demonstrate the effectiveness and efficiency of our solutions for a moving target in presence of obstacles.

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