This report investigates how the construction and query time of multiple spatial partitioning data structures is impacted by spatial distribution of and number of agents in a crowd simulation. In addition a method is investigated for updating the data structures less frequently at the cost of increasing the radius queried, without affecting the correctness of the queries. The data structures are tested in a simulation using a Boids model and update and query times are measured. It is found that the performance of the grid is better than the quad tree and the kd- tree for low number of agents, but deteriorates more quickly when the number of agents increase. It is also found that this approach can decrease the sum of time spent updating and the time spent querying in the simulation. The effectiveness of this method is highly dependent on the update of the data structure. / Denna rapport undersöker hur konstruktion och grannsökning av flera datastrukturer för spatial partitionering påverkas av spatial fördelning av simuleringens agenter och antal agenter i simuleringen. Dessutom undersöks en metod för att uppdatera datastrukturerna mindre ofta, på bekostnad av att utöka grannsökningens radie, utan att påverka grannsökningens korrekthet. Datastrukturerna testas i en simulering baserad på Boids och uppdaterings- och frågetider för datastrukturerna mäts. Det visar sig att prestandan av grid är bättre än prestandan av quad tree och kd- tree för ett litet antal agenter, men att prestandan för grid försämras snabbare när antalet agenter ökar. Dessutom visar sig denna metod kunna ge en minskning i den totala tiden som går åt till att göra grannsökningar och uppdateringar av datastrukturen. Hur effektiv denna metod är beror i hög grad på hur lång uppdateringstiden är för den använda datastrukturen.

Water is a vital resource for species inhabiting arid and semi-arid regions and can shape the biotic communities that we observe. Because water is considered a limiting resource for many species in desert environments, there is the potential for competitive interactions between species to occur at or around water sources. For this dissertation I tested hypotheses related to resource competition among different species of wildlife in the Great Basin and Mojave Deserts of western Utah. Chapter one evaluated the influence of feral horses (Equus caballus) on patterns of water use by communities of native birds and mammals. Chapter two determined if feral horses competed with pronghorn (Antilocapra americana) and mule deer (Odocoileus hemionus) for access to water. In chapters one and two, we found evidence that horses compete with native wildlife for water. In chapter one, horses were associated with decreased richness and diversity of native species at water sources. Native species also had fewer visits and spent less time at water sources frequented by horses. In chapter two, we found that pronghorn and mule deer used water sources less often where horse activity was high. There were also significant differences in temporal activity for pronghorn, but not mule deer, at horse-occupied sites versus sites where horses were absent or uncommon. Our results indicated that horses spatially and temporally displaced other species at water sources providing evidence of a negative influence on how communities of native wildlife access a limited resource in an arid environment. Chapter three assessed whether dominant carnivores (coyote (Canis latrans) and bobcat (Lynx rufus)) negatively influenced the spatial use of water sources by the subordinate kit fox (Vulpes macrotis). Our results did not reveal strong negative associations between kit fox visits to water sources and visits by dominant carnivores; in fact, dominant carnivores contributed very little to the use of water by kit foxes. Instead, kit fox visits were more closely associated with habitat features at water sources. Our findings indicate that dominant carnivores are not the primary driver of use of water sources by subordinate carnivores. Chapter four evaluated whether a simulated loss of water due to climate change/increased human use would differentially affect desert bats based on flight morphology and maneuverability. When we experimentally reduced surface area of water sources, larger, less-maneuverable bats experienced a 69% decrease in drinking success and increased competition with smaller, maneuverable bats. Anticipated reductions in the sizes of water sources due to climate change may lead to species with less maneuverability being unable to access water efficiently and facing increased competition from more agile bats.

Práce se zabývá detekcí kolizí v 3D simulačním prostoru. V první části jsou popsány nejpoužívanější algoritmy pro detekci, stejně jako některé knihovny hotových řešení. Druhá část práce obsahuje popis testovacího softwaru vytvořeného na základě knihovny OpenGL, včetně popisu důležitých částí. V poslední části práce jsou také prezentovány výsledky testování a porovnání vybraných algoritmů na vytvořených testovacích úlohách.

The interest in autonomous surveillance has increased due to advances in autonomous systems and sensor theory. This thesis is a preliminary study of the cooperation between UGVs and stationary sensors when monitoring a dedicated area. The primary focus is the path planning of a UGV for different initial intrusion alarms. Cell decomposition, i.e., spatial partitioning, of the area of surveillance was utilized, and the objective function is based on the probability of a present intruder in each cell. These probabilities were modeled through two different methods: ExpPlanner, utilizing an exponential decay function. Markov planner, utilizing a Markov chain to propagate the probabilities. The performance of both methods improves when a confident alarm system is utilized. By prioritizing the direction of the planned paths, the performances improved further. The Markov planner outperforms the ExpPlanner in finding a randomly walking intruder. The ExpPlanner is suitable for passive surveillance, and the Markov planner is suitable for ”aggressive target hunting”.