Grid-Obstacle Representations with Connections to Staircase Guarding

In this paper, we study grid-obstacle representations of graphs where we assign grid-points to vertices and define obstacles such that an edge exists if and only if an $xy$-monotone grid path connects the two endpoints without hitting an obstacle or another vertex. It was previously argued that all planar graphs have a grid-obstacle representation in 2D, and all graphs have a grid-obstacle representation in 3D. In this paper, we show that such constructions are possible with significantly smaller grid-size than previously achieved. Then we study the variant where vertices are not blocking, and show that then grid-obstacle representations exist for bipartite graphs. The latter has applications in so-called staircase guarding of orthogonal polygons; using our grid-obstacle representations, we show that staircase guarding is \textsc{NP}-hard in 2D.Comment: To appear in the proceedings of the 25th International Symposium on Graph Drawing and Network Visualization (GD 2017

The VC-Dimension of Limited Visibility Terrains

Visibility problems are fundamental to computational geometry, and many versions of geometric set cover where coverage is based on visibility have been considered. In most settings, points can see "infinitely far" so long as visibility is not "blocked" by some obstacle. In many applications, this may be an unreasonable assumption. In this paper, we consider a new model of visibility where no point can see any other point beyond a sight radius ?. In particular, we consider this visibility model in the context of terrains. We show that the VC-dimension of limited visibility terrains is exactly 7. We give lower bound construction that shatters a set of 7 points, and we prove that shattering 8 points is not possible

A GROWTH-BASED APPROACH TO THE AUTOMATIC GENERATION OF NAVIGATION MESHES

Providing an understanding of space in game and simulation environments is one of the major challenges associated with moving artificially intelligent characters through these environments. The usage of some form of navigation mesh has become the standard method to provide a representation of the walkable space in game environments to characters moving around in that environment. There is currently no standardized best method of producing a navigation mesh. In fact, producing an optimal navigation mesh has been shown to be an NP-Hard problem. Current approaches are a patchwork of divergent methods all of which have issues either in the time to create the navigation meshes (e.g., the best looking navigation meshes have traditionally been produced by hand which is time consuming), generate substandard quality navigation meshes (e.g., many of the automatic mesh production algorithms result in highly triangulated meshes that pose problems for character navigation), or yield meshes that contain gaps of areas that should be included in the mesh and are not (e.g., existing growth-based methods are unable to adapt to non-axis-aligned geometry and as such tend to provide a poor representation of the walkable space in complex environments). We introduce the Planar Adaptive Space Filling Volumes (PASFV) algorithm, Volumetric Adaptive Space Filling Volumes (VASFV) algorithm, and the Iterative Wavefront Edge Expansion Cell Decomposition (Wavefront) algorithm. These algorithms provide growth-based spatial decompositions for navigation mesh generation in either 2D (PASFV) or 3D (VASFV). These algorithms generate quick (on demand) decompositions (Wavefront), use quad/cube base spatial structures to provide more regular regions in the navigation mesh instead of triangles, and offer full coverage decompositions to avoid gaps in the navigation mesh by adapting to non-axis-aligned geometry. We have shown experimentally that the decompositions offered by PASFV and VASFV are superior both in character navigation ability, number of regions, and coverage in comparison to the existing and commonly used techniques of Space Filling Volumes, Hertel-Melhorn decomposition, Delaunay Triangulation, and Automatic Path Node Generation. Finally, we show that our Wavefront algorithm retains the superior performance of the PASFV and VASFV algorithms while providing faster decompositions that contain fewer degenerate and near degenerate regions. Unlike traditional navigation mesh generation techniques, the PASFV and VASFV algorithms have a real time extension (Dynamic Adaptive Space Filling Volumes, DASFV) which allows the navigation mesh to adapt to changes in the geometry of the environment at runtime. In addition, it is possible to use a navigation mesh for applications above and beyond character path planning and navigation. These multiple uses help to increase the return on the investment in creating a navigation mesh for a game or simulation environment. In particular, we will show how to use a navigation mesh for the acceleration of collision detection

Adapting Swarm Intelligence for the Self-Assembly of Prespecified Artificial Structures

The self-assembly problem involves designing individual behaviors that a collection of agents can follow in order to form a given target structure. An effective solution would potentially allow self-assembly to be used as an automated construction tool, for example, in dangerous or inaccessible environments. However, existing methodologies are generally limited in that they are either only capable of assembling a very limited range of simple structures, or only applicable in an idealized environment having few or no constraints on the agents' motion. The research presented here seeks to overcome these limitations by studying the self-assembly of a diverse class of non-trivial structures (building, bridge, etc.) from different-sized blocks, whose motion in a continuous, three-dimensional environment is constrained by gravity and block impenetrability. These constraints impose ordering restrictions on the self-assembly process, and necessitate the assembly and disassembly of temporary structures such as staircases. It is shown that self-assembly under these conditions can be accomplished through an integration of several techniques from the field of swarm intelligence. Specifically, this work extends and incorporates computational models of distributed construction, collective motion, and communication via local signaling. These mechanisms enable blocks to determine where to deposit themselves, to effectively move through continuous space, and to coordinate their behavior over time, while using only local information. Further, an algorithm is presented that, given a target structure, automatically generates distributed control rules that encode individual block behaviors. It is formally proved that under reasonable assumptions, these rules will lead to the emergence of correct system-level coordination that allows self-assembly to complete in spite of environmental constraints. The methodology is also verified experimentally by generating rules for a diverse set of structures, and testing them via simulations. Finally, it is shown that for some structures, the generated rules are able to parsimoniously capture the necessary behaviors. This work yields a better understanding of the complex relationship between local behaviors and global structures in non-trivial self-assembly processes, and presents a step towards their use in the real world

Biophilic primary schools in cold climates : design opportunities fostering multisensory experiences and well-being

Les enfants passent plus du tiers de leur journée à l'école où la plupart de leurs activités d'apprentissage se déroulent à l'intérieur. Au Québec, Canada, la plupart des écoles primaire sont atteint la fin d'un premier cycle de vie et doivent être rénovées pour assurer un environnement d'apprentissage de qualité. Ces rénovations offrent le potentiel de favoriser la réussite éducative et le bien-être des élèves et du personnel scolaire en améliorant la qualité de l'environnement visuel, thermique, olfactif et auditif. Au Québec, des variations saisonnières importantes influencent l'expérience de la nature et la relation entre les espaces intérieurs et extérieurs. Cette recherche vise à développer une approche de rénovation biophilique des écoles primaires québécoises qui tient compte de la diversité saisonnière. Dans le contexte de la rénovation des écoles québécoises pour améliorer l'expérience et le bien-être des occupants, cette thèse s'appuie sur l'évaluation post-occupationnelle et le design informé par les données probantes (evidence-based design) pour caractériser les déterminants mesurables et perceptuels de l'architecture biophilique en climat froid. Cette recherche vise à (1) recenser les études sur les relations entre le design biophilique et le bien-être, avec une attention particulière pour les écoles en climats froids, (2) diagnostiquer les qualités biophiliques des bâtiments existants avant de réaliser des visites de sites, (3) évaluer les expériences biophiliques lors de visites d'écoles dans une démarche d'évaluation post-occupationnelle et (4) examiner les configurations spatiales qui engendrent des expériences biophiliques et proposer une approche de conception pour les environnements d'apprentissage des enfants. Cette thèse développe des outils pour soutenir la réalisation de diagnostics et proposer des solutions à plusieurs échelles architecturales qui favorisent les expériences multisensorielles liées aux forces naturelles et aux organismes vivants (ex. lumière, vent, neige et végétation). Cette approche multiméthodes comprend des analyses de dessins d'architecture, des visites d'écoles et des mesures des conditions environnementales dans un échantillon d'écoles primaires québécoises. Dans une optique de recherche et développement, des analyses de précédents et des ateliers d'architecture ont permis d'étudier l'expérience multisensorielle des ambiances physiques dans des projets d'agrandissement d'écoles. Premièrement, l'outil diagnostique basé sur la géométrie spatiale des bâtiments utilise les éléments mesurables des dessins d'architecture pour évaluer le design biophilique. Une combinaison des critères de certification des bâtiments, des principes de conception bioclimatique et des stratégies de design biophilique offre un moyen simple d'analyser les qualités architecturales d'une école, ce qui s'avère bénéfique aux étapes préliminaires du diagnostic et de la conception. Deuxièmement, l'outil de représentation des expériences biophiliques (BERT) évalue subjectivement des caractéristiques environnementales (comme le soleil, la neige et la végétation) et décrit les sensations, les sentiments, la compréhension et l'affiliation à la nature que les espaces engendrent. Utilisé lors des visites de site, il permet aux architectes de confirmer ou d'infirmer les possibilités de design identifiées à l'aide de dessins d'architecture. BERT permet d'évaluer plusieurs espaces dans un court laps de temps tout en minimisant les perturbations pour les élèves et le personnel. Cet outil diagnostique a servi lors de visites d'écoles en hiver pour indiquer où les caractéristiques environnementales pourraient être améliorées pour favoriser le bien-être des occupants. Alors que les outils diagnostiques concernent des dessins d'architecture ou des expériences in situ, les outils d'aide à la conception développés dans la thèse intègrent ces deux aspects pour favoriser le bien-être en milieu scolaire. Le vocabulaire de design biophilique illustre les possibles expériences multisensorielles d'un espace. Il classe les éléments architecturaux et les espaces selon le degré d'intériorité - extériorité et de contiguïté. Les schémas de design biophilique complètent le vocabulaire de design biophilique pour aider les architectes à explorer les configurations spatiales qui engendrent des expériences biophiliques dans les écoles. Les 38 schémas proposés sont organisés par échelle architecturale et type d'espace (intérieurs, semi-fermés et extérieurs). Ces outils offrent une représentation visuelle simplifiée des expériences de la nature et une organisation des stratégies de design à diverses échelles du bâtiment. Les méthodes développées dans cette thèse aident à caractériser les opportunités et défis architecturaux pour les expériences biophiliques dans les écoles québécoises. Ces outils guident les architectes dès l'évaluation préliminaire d'un bâtiment, lors des visites de sites, à l'étape de la conception et dans l'évaluation post-occupationnelle des écoles rénovées.Children spend over a third of their day at school where most of their learning activities occur indoors. In the province of Quebec, Canada, most primary schools have reached the end of a first life cycle and require renovations to ensure a quality learning environment. Renovating these buildings offers the potential to foster academic success and the well-being of students and school staff by enhancing the quality of the visual, thermal, olfactory and auditory environment. In Quebec, the relationship between interior and exterior spaces is a fundamental aspect in architectural design considering the important seasonal variations that generate different experiences of nature throughout the year. This research aims to develop an approach to the biophilic redesign of learning environments in Quebec schools by taking into consideration seasonal diversity. In the context of renovating Quebec schools to enhance occupant experiences and well-being, this thesis uses a post-occupancy evaluation and evidence-based design framework to characterise measurable and perceptual determinants of biophilic architecture in cold climates. This research aims to (1) review studies into the relationships between biophilic design and well-being, with particular consideration for schools in cold climates, (2) diagnose the biophilic qualities of existing buildings before site visits are carried out, (3) assess people's experiences of nature during building walkthroughs in post-occupancy evaluations and (4) examine the forms and spatial configurations that engender biophilic experiences and propose a design approach for children's learning environments. This thesis develops an ensemble of architectural tools to support the realisation of diagnoses and to identify solutions at several building scales that promote multisensory experiences of natural forces and living organisms (such as light, wind, snow and vegetation). This multi-method approach includes analyses of architectural drawings, school visits and measurements of environmental conditions in a sample of primary schools in Quebec. Within a research and development framework, precedent analyses and architectural design studios offer the opportunity to investigate visual, thermal, olfactory and auditory experiences in simulated school addition projects. Firstly, the diagnostic tool based on spatial geometry uses the measurable elements contained in architectural drawings to assess biophilic design. A combination of building certification criteria, bioclimatic design principles and biophilic design guidelines offers a simple means of assessing architectural qualities while considering the climatic context, which can be highly beneficial in the early diagnostic and design stages. Secondly, the Biophilic Experience Representation Tool (BERT) subjectively evaluates a selection of environmental features (such as sun, snow and vegetation) and describes the sensations, feelings, understanding and affiliation with nature that the settings engender. Used during site visits, it enables architects to confirm or disprove the design opportunities identified using architectural drawings. The value of using BERT lies in its ability to enable architects to evaluate multiple spaces in a short period of time while minimising disruptions for school children and staff. This diagnostic tool was used during school visits in winter to indicate where environmental features could be enhanced to foster the well-being of occupants. While the diagnostic tools focus on architectural drawings or in situ experiences, the design tools combine both aspects to offer a design approach that fosters experiences of nature in children's learning environments. The biophilic design vocabulary offers a common way of describing potential biophilic experiences. It categorises architectural elements and spaces in terms of spatial enclosure, adjacency, abiotic nature and biotic nature. The biophilic design schemas expand on the biophilic design vocabulary to help architects explore the spatial configurations that engender biophilic experiences in schools. Drawing on pattern thinking, the 38 schemas are organised across design scales and indoor, semi-enclosed and outdoor spaces. These design tools provide a simplified visual representation of experiences of nature and an organisation of design strategies throughout building scales in the preliminary design stages. The diagnostic and design methods developed in this thesis help to characterise current challenges and opportunities for biophilic experiences in Quebec schools. These tools therefore provide valuable guidance from the early assessment of a building, during site visits, in the design development process and in the post-occupancy evaluation of the renovated schools

Change blindness: eradication of gestalt strategies

Arrays of eight, texture-defined rectangles were used as stimuli in a one-shot change blindness (CB) task where there was a 50% chance that one rectangle would change orientation between two successive presentations separated by an interval. CB was eliminated by cueing the target rectangle in the first stimulus, reduced by cueing in the interval and unaffected by cueing in the second presentation. This supports the idea that a representation was formed that persisted through the interval before being 'overwritten' by the second presentation (Landman et al, 2003 Vision Research 43149–164]. Another possibility is that participants used some kind of grouping or Gestalt strategy. To test this we changed the spatial position of the rectangles in the second presentation by shifting them along imaginary spokes (by ±1 degree) emanating from the central fixation point. There was no significant difference seen in performance between this and the standard task [F(1,4)=2.565, p=0.185]. This may suggest two things: (i) Gestalt grouping is not used as a strategy in these tasks, and (ii) it gives further weight to the argument that objects may be stored and retrieved from a pre-attentional store during this task

A Hybrid Approach to Procedural Dungeon Generation

This thesis presents a novel approach to the Procedural Content Generation (PCG) of both maze and dungeon environments. The solution we propose in this thesis borrows techniques from both Procedural Content Generation via Machine Learning as well as Constructive PCG methods. The approach we take involves decomposing the problem of level generation into a series of stages which begins with the production of macro-level functional structures and ends with micro-level aesthetic details; specifically, we train a Deep Convolutional Neural Network to produce high-quality mazes, which in turn, are transformed into the rooms of larger dungeon levels using a constructive algorithm. For our dungeon’s micro-level details, we use a context-free grammar for the instantiation of interactable puzzle elements, and an n-gram model for decorating our dungeon\u27s entrance rooms. This unique combination of methods successfully generates a large number of visually impressive game levels without compromising on any desirable PCG metrics such as speed, reliability, controllability, expressivity, or believability