Browsing by Author "Löffler, Maarten"

Adjacencypreserving spatial treemaps
Buchin, Kevin; Eppstein, David; Löffler, Maarten; Nöllenburg, Martin; Silveira, Rodrigo Ignacio (2016)
Article
Open AccessRectangular layouts, subdivisions of an outer rectangle into smaller rectangles, have many applications in visualizing spatial information, for instance in rectangular cartograms in which the rectangles represent geographic ... 
A faster algorithm to compute the visibility map of a 1.5D terrain
Löffler, Maarten; Saumell, Maria; Silveira, Rodrigo Ignacio (2014)
Conference report
Open AccessGiven a 1.5D terrain, i.e., an x monotone polygonal line in R 2 with n vertices, and 1 m n viewpoints placed on some of the terrain vertices, we study the problem of computing the parts of the terrain that are visible ... 
Colored spanning graphs for set visualization
Hurtado Díaz, Fernando Alfredo; Korman, Matias; Van Kreveld, Matias; Löffler, Maarten; Sacristán Adinolfi, Vera; Shioura, Akiyoshi; Silveira, Rodrigo Ignacio; Speckmann, Bettina; Tokuyama, Takeshi (201803)
Article
Open AccessWe study an algorithmic problem that is motivated by ink minimization for sparse set visualizations. Our input is a set of points in the plane which are either blue, red, or purple. Blue points belong exclusively to the ... 
Colored spanning graphs for set visualization
Hurtado Díaz, Fernando Alfredo; Korman Cozzetti, Matías; Van Kreveld, Matias; Löffler, Maarten; Sacristán Adinolfi, Vera; Silveira, Rodrigo Ignacio; Speckmann, Bettina (Springer, 2013)
Conference report
Open AccessWe study an algorithmic problem that is motivated by ink minimization for sparse set visualizations. Our input is a set of points in the plane which are either blue, red, or purple. Blue points belong exclusively to the ... 
Computing correlation between piecewiselinear functions
Agarwal, Pankaj; Aronov, Boris; Van Kreveld, Matias; Löffler, Maarten; Silveira, Rodrigo Ignacio (2013)
Article
Restricted access  publisher's policyWe study the problem of computing correlation between two piecewiselinear bivariate functions defined over a common domain, where the surfaces they define in three dimensionspolyhedral terrainscan be transformed ... 
Computing similarity between piecewiselinear functions
Agarwal, Pankaj; Aronov, Boris; Kreveld, Marc van; Löffler, Maarten; Silveira, Rodrigo Ignacio (ACM Press. Association for Computing Machinery, 2010)
Conference report
Open AccessWe study the problem of computing the similarity between two piecewiselinear bivariate functions de ned over a common domain, where the surfaces they de ne in 3Dpolyhedral terrainscan be transformed vertically by a ... 
Flow computations on imprecise terrains
Driemel, Anne; Haverkort, Herman; Löffler, Maarten; Silveira, Rodrigo Ignacio (2013)
Article
Open AccessWe study water flow computation on imprecise terrains. We consider two approaches to modeling flow on a terrain: one where water flows across the surface of a polyhedral terrain in the direction of steepest descent, and ... 
Flow computations on imprecise terrains
Driemel, Anne; Haverkort, Herman; Löffler, Maarten; Silveira, Rodrigo Ignacio (Springer Verlag, 2011)
Conference report
Restricted access  confidentiality agreementWe study water flow computation on imprecise terrains. We consider two approaches to modeling flow on a terrain: one where water flows across the surface of a polyhedral terrain in the direction of steepest descent, and ... 
Geomasking through perturbation, or counting points in circles
Löffler, Maarten; Luo, Jun; Silveira, Rodrigo Ignacio (2017)
Conference report
Restricted access  publisher's policyMotivated by a technique in privacy protection, in which n points are randomly perturbed by at most a distance r, we study the following problem: Given n points and m circles in the plane, what is the maximum r such that ... 
Median trajectories
Buchin, Kevin; Buchin, Maike; Kreveld, Marc van; Löffler, Maarten; Silveira, Rodrigo Ignacio; Wenk, Carola; Wiratma, Lionov (201205)
Article
Open AccessWe investigate the concept of a median among a set of trajectories. We establish criteria that a “median trajectory” should meet, and present two different methods to construct a median for a set of input trajectories. The ... 
On the complexity of barrier resilience for fat regions and bounded ply
Korman, Matias; Löffler, Maarten; Silveira, Rodrigo Ignacio; Strash, Darren (201806)
Article
Open AccessIn the barrier resilience problem (introduced by Kumar et al., Wireless Networks 2007), we are given a collection of regions of the plane, acting as obstacles, and we would like to remove the minimum number of regions so ... 
Processing aggregated data : the location of clusters in health data
Buchin, Kevin; Buchin, Maike; Kreveld, Marc van; Löffler, Maarten; Luo, Jun; Silveira, Rodrigo Ignacio (201207)
Article
Restricted access  publisher's policySpatially aggregated data is frequently used in geographical applications. Often spatial data analysis on aggregated data is performed in the same way as on exact data, which ignores the fact that we do not know the actual ... 
Regionbased approximation algorithms for visibility between imprecise locations
Buchin, Kevin; Kostitsyna, Irina; Löffler, Maarten; Silveira, Rodrigo Ignacio (2015)
Conference report
Restricted access  publisher's policyIn this paper we present new geometric algorithms for approximating the visibility between two imprecise locations amidst a set of obstacles, where the imprecise locations are modeled by continuous probability distributions. ... 
Regionbased approximation of probability distributions (for visibility between imprecise points among obstacles)
Buchin, Kevin; Kostitsyna, Irina; Löffler, Maarten; Silveira, Rodrigo Ignacio (201907)
Article
Open AccessLet p and q be two imprecise points, given as probability density functions on R2 , and let O be a set of disjoint polygonal obstacles in R2 . We study the problem of approximating the probability that p and q can see each ... 
Regionbased approximation of probability distributions (for visibility between imprecise points among obstacles)
Buchin, Kevin; Kostitsyna, Irina; Löffler, Maarten; Silveira, Rodrigo Ignacio (2014)
Conference report
Open AccessLet p and q be two imprecise points, given as prob ability density functions on R 2 , and let R be a set of n line segments in R 2 . We study the problem of approximating the probability that p and q can see each other; ... 
Removing local extrema from imprecise terrains
Gray, Chris; Kammer, Frank; Löffler, Maarten; Silveira, Rodrigo Ignacio (201208)
Article
Open AccessIn this paper we consider imprecise terrains, that is, triangulated terrains with a vertical error interval in the vertices. In particular, we study the problem of removing as many local extrema (minima and maxima) as ... 
Terrain visibility with multiple viewpoints
Hurtado Díaz, Fernando Alfredo; Löffler, Maarten; Matos, Inés P.; Sacristán Adinolfi, Vera; Saumell, Maria; Silveira, Rodrigo Ignacio; Staals, Frank (Springer, 2013)
Conference report
Open AccessWe study the problem of visibility in polyhedral terrains in the presence of multiple viewpoints. We consider three fundamental visibility structures: the visibility map, the colored visibility map, and the Voronoi visibility ...