Le balayage lidar aéroporté permet la production de modèles numériques de terrain (MNT) précis et à haute résolution. Cette thèse fait partie d'un projet où le DTM est utilisé pour évaluer la hauteur d'eau en crue et estimer le risque qu'elle atteigne les ouvertures inférieures des bâtiments. Ce travail est fait pour aider les décideurs à évaluer les dommages causés par les inondations. Cependant, le DTM est souvent présenté sans estimation de sa précision. La comparaison avec la vérité terrain est une approche courante pour estimer la qualité du DTM. Alors que la fiabilité d'une telle approche dépend de divers facteurs dont la taille de l'échantillon, l'accessibilité sur le terrain, la distribution et une assez grande diversité de vérité terrain, ce qui a un coût et est quelque peu irréalisable à l'échelle de la province de Québec. Par conséquent, l'objectif principal de cette recherche est de concevoir une méthode qui pourrait fournir une estimation locale de l'erreur sans aucune dépendance à des ensembles de données tiers. À cet égard, nous profitons du krigeage géostatistique comme estimateur alternatif de la qualité. Le défi de considérer une variation constante dans l'espace nous amène à proposer une méthode non stationnaire qui aboutit à l'estimation locale de l'erreur d'élévation du MNT. La performance de la méthode présentée a été validée par la comparaison avec l'évaluation de la vérité terrain. Les résultats ont révélé que notre méthode est fiable dans les zones urbaines et semi-urbaines, en particulier dans les zones agricoles et résidentielles sauf dans les forêts qui sont dues à leur plus faible densité. / Airborne lidar scanning allows the production of accurate and high-resolution digital terrain models (DTM). This thesis is part of a project where the DTM is used to assess the water height in flood and estimate the risk it reaches the lower openings in buildings. This work is done to support decision-makers in estimating damages caused by floods. However, DTM is often presented without an estimation of its accuracy. Comparison with ground truth is a common approach to estimating the quality of DTM. Whereas the reliability of such an approach depends on various factors including sample size, accessibility on the field, distribution, and a large enough diversity of ground truth, which comes at a cost and is somewhat unfeasible in the scale of Quebec province. Therefore, the main objective of this research is to design a method that could provide a local estimation of error without any dependency on third-party datasets. In this regard, we take advantage of geostatistical kriging as an alternative quality estimator. The challenge of considering constant variation across the space brings us to propose a non-stationary method that results in the local estimation of DTM elevation error. The performance of the presented method was validated with the comparison with ground truth assessment. The results revealed that our method is reliable in urban and semi-urban areas, especially in farmland and residential areas except in forests which are due to their lowest density.

Road roughness is an important factor in determining the quality of a stretch of road. The International Roughness Index, a specific measure of road roughness, is widely used metric. However, in order to measure roughness, an accurate road profile must exist. To measure the roads, terrain profiling systems are commonly used. Modern systems based on laser scanners and inertial navigation systems (INS) are able to measure thousands of data points per seconds over a wide path. However, because of the subsystems in the profiling systems, they are susceptible to errors that reduce the accuracy of the measurements. Thus, both major subsystems - the laser and the navigation system - must be accurate and synchronized for the road to be correctly scanned. The sensors' mounting was investigated to ensure that the vehicle motion is accurately captured and accounted for, demonstrated in the Vehicle Terrain Performance Lab's (VTPL) Ford Explorer profilometer. Next, INS errors were addressed. These may include drift in the inertial measurement unit or errors due to poor reception with the global navigation satellite system. The solution to these errors was demonstrated through the VTPL's HMMWV profilometer. / Master of Science

Hurricane Matthew (2016) was a category 5 hurricane that interacted with remote terrain over northern South America in the early stages of its life cycle. Because tropical cyclone (TC) precipitation and convection are known to be crucial factors in the understanding and forecasting of TC intensity, this study investigates how this terrain impacted Hurricane Matthew's rainband structure. Remote terrain is hypothesized to play a role in the strength of TC rainband convection by modifying the thermodynamic environment such that subsiding dry air advects over an extremely moist ocean surface layer leading to increased moist static instability. To investigate this hypothesis, this study utilizes the Advanced Research Weather and Research Forecasting Model (WRF-ARW) to create a high-resolution (2-km horizontal grid spacing) control simulation (CTL) of Hurricane Matthew and a second experimental simulation with a 50% reduction of terrain height over the topography of northern South America (T50). This study focuses on a particular convective rainband positioned downstream of the terrain that displayed prolonged robust convection during the initial stages of Hurricane Matthew's life cycle. Results indicate that characteristics of this robust rainband are consistent with prior research on an inner core rainband called a principal rainband. This rainband does not display differences in intensity in the two simulations but is located closer to the TC center and more persistent in the control simulation. In the region downstream of the topography, significantly (p < 0.05) drier conditions exist in the control simulation, which is consistent with the hypothesis that downslope motion would lead to a drier air mass. TC structural changes are also apparent, with a weaker TC in the reduced topography simulation. This research emphasizes the potentially important role of terrain distant from the TC center with possible influences on TC rainband convection and warm core structure. Conclusions of this research are limited due to the small sample size of a single case study. An ensemble modeling study and additional cases are needed for a more thorough conclusion on the impact of remote terrain on TC structure. / Master of Science / Predicting the intensity of hurricanes remains a monumental challenge for hurricane forecasters. Many factors can influence the intensity of hurricanes, including the strength, frequency, and spatial distribution of hurricane rainbands (band of precipitation). The hypothesis for this study is that terrain distant from the hurricane center can alter the hurricane environment and cause more frequent and stronger rainbands to form. To assess this hypothesis, I use a weather model to simulate Hurricane Matthew (2016) while it was interacting with remote terrain over northern South America on September 30 - October 1, 2016. Then I use the same model, but with terrain height reduced by 50% over northern South America and analyze the similarities and differences in the hurricane structure and rainband patterns. The results of this study suggest that terrain did not alter the peak rain rates in the hurricane rainbands but may have caused more frequent, widespread, and prolonged precipitation. Also, differences in hurricane structure were apparent when comparing the two model simulations. The reduced terrain simulation produced a weaker hurricane, lending some evidence to support the hypothesis that terrain may have played a role in altering the hurricane structure. These results demonstrate the potential importance of distant terrain on forecasting hurricane precipitation and intensity.

The aim of the present project was to quantify and compare differences in impact performance and damping effectiveness among various off-road bicycle suspension systems. Two experiments were conducted to compare suspensions. Fork impact performance was tested by measuring peak antero-posterior braking forces and impulses during impact with bumps of 6- and 10-cm height for five mountain bike suspension systems. These results were compared to a rigid fork condition. Comparisons among suspension systems showed small but significant differences in performance. While only marginal differences in peak force were found for the suspension conditions, more substantial differences in braking impulse were observed. Air-Oil design forks had the lowest braking impulse for the range of speeds and impact characteristics of this experiment. In another setting, an analysis of acceleration signals over a range of frequencies on two surface conditions (gravel and trail) was conducted to assess the damping effectiveness of the five suspension systems. The mountain bike was equipped with accelerometers mounted at the axle and frame. A spectral analysis of the signal was performed for each signal to provide a measure of fork effectiveness. Results showed that accelerations ranged from -33 to +40 g at the axle and from -13 to +13 g at the frame, while spectral analyses of the acceleration signals revealed two distinct frequency regions from 0 to 100 Hz and from 300 to 400 Hz. The various suspension systems were all effective in attenuating vibration over the first region. Vibration amplitudes at the frame were considerably less than at the axle for the suspension conditions while similar axle-frame vibrations were observed with the rigid fork. Lower frequency vibration amplitudes were typically greater on the trail than on gravel. In the frequency region between 300-400 Hz, the signal was attenuated at the frame for all conditions including the rigid fork. The quantification and comparison process of the various suspension forks using impulse provided an objective marker for performance, and allowed differentiation between various suspension conditions. Moreover, the effectiveness analysis through the use of accelerometers provided insight into the range of frequencies dampened by a suspension. The lower frequency range dampening suggested that effectiveness of a suspension fork can be quantified even though the experiment did not conclusively differentiate between the forks. / Graduation date: 2001

Synthetically generated terrain models are useful across a broad range of applications, including computer generated art & animation, virtual reality and gaming, and architecture. Existing algorithms for terrain generation suffer from a number of problems, especially that of being limited in the types of terrain that they can produce and of being difficult for the user to control. Typical applications of synthetic terrain have several factors in common: first, they require the generation of large regions of believable (though not necessarily physically correct) terrain features; and second, while real-time performance is often needed when visualizing the terrain, this is generally not the case when generating the terrain. In this thesis, I present a new, design-by-example method for synthesizing terrain height fields. In this approach, the user designs the layout of the terrain by sketching out simple regions using a CAD-style interface, and specifies the desired terrain characteristics of each region by providing example height fields displaying these characteristics (these height fields will typically come from real-world GIS data sources). A height field matching the user's design is generated at several levels of detail, using a genetic algorithm to blend together chunks of elevation data from the example height fields in a visually plausible manner. This method has the advantage of producing an unlimited diversity of reasonably realistic results, while requiring relatively little user effort and expertise. The guided randomization inherent in the genetic algorithm allows the algorithm to come up with novel arrangements of features, while still approximating user-specified constraints.

This thesis extracts organizational lessons from the U.S. Army's Human Terrain Teams. In the past, the Human Terrain Teams have been the topic of various debates, but none discussed their performance. Studying what influences how Human Terrain Teams perform is important to the National Security System to improve its use of socio-cultural knowledge during conflicts. A contextual narrative of team members formally involved with Human Terrain Teams and information from journalistic articles tells the story of what organizational characteristics affected the performance of the U.S. Army's Human Terrain Teams. / Master of Arts

No description available.

For decades, the pavement engineering community has continued to drive improvements in accuracy and repeatability of terrain measurement systems. Traditional terrain measurement systems are tailored for a measuring a specific scale and resolution and hence application scope. These systems tend to focus on surface roughness alone and reject either fine macrotexture or large-scale global features. This work proposes a novel improvement to the terrain measurement system, by increasing the capability to measure the terrain surface at a variety of scales. By increasing the scales of measurement, desired aspects of the terrain profile can be accurately obtained for a wide variety of applications without having to omit large-scale features or macrotexture. In addition to increasing the capabilities of the traditional terrain measurement system, methods for addressing and minimizing sources of error within the system are developed. Major sources of error in terrain measurement systems, which compromise the accuracy and repeatability of the resulting measured terrain, include scanning laser uncertainty, inertial navigation system (INS) uncertainty and drift, triggering and time synchronization, system misalignment, and post-processing errors. These errors are addressed, and an improved Vehicle Terrain Measurement System (VTMS) is proposed. A triggering and time synchronization system is developed and insight into the development of this system for a terrain measurement system is gained. All three scanning lasers are individually assessed for linearity, with sample profiles analyzed for agreement. The improved VTMS represents a significant development in terrain measurement systems. / Master of Science

The emergence of high-fidelity vehicle and tire models has raised the requirements for terrain measurement capabilities. Inaccuracies that were once tolerable for measurement of general terrain roughness are no longer acceptable for these new applications. The techniques in this work seek to improve the quality of terrain measurement in addition to providing an objective way to describe the accuracy of these measurements. The first portion of this work develops an accuracy verification procedure for terrain measurement systems. This procedure involves a static test to assess the limitations of the profiler's laser height sensor, and a corresponding dynamic test to evaluate the limitations of the positioning sensors. Even with a well calibrated system, inertial errors will accumulate. The second portion of this work develops techniques to address these inertial errors in the data post-processing phase. A general correction technique is developed for any terrain type and a more computationally efficient technique is developed for smooth surfaces. For basic ride and handling simulations, 3D terrain surfaces are computationally impractical, as the models used for these simulations only require point excitation. Current road profilers acquiring these 2D data use single-point lasers that capture localized disturbances that would be mechanically filtered by the tire and suspension in the physical vehicle system. The final chapter in this work develops a method to extract a 2D terrain profile from a 3D terrain surface. By considering all of the information in the tire contact patch, the filtering properties of the tire are approximately emulated. / Master of Science

This thesis focuses on the extent to which the physical terrain features across Egypt, Libya and Tunisia affected British operations throughout the campaign in North Africa during the Second World War. The study analyses the terrain from the operational and tactical perspectives and argues that the landscape features heavily influenced British planning and operations. These should now be considered alongside other standard military factors when studying military operations. This thesis differs from previous studies as it considers these additional factors from June 1940 until the Axis surrender in May 1943. Until now it has been widely assumed that much of the North African coastal sector was a broadly flat, open region in which mobile armoured operations were paramount. However this work concentrates on the British operations to show they were driven by the need to capture and hold key features across each battlefield. At the operational level planning was led by the need to hold key ground in Libya and across the province of Cyrenaica during the crucial middle period of the campaign. A secondary theme of the thesis argues that British forces began to improvise some tactical doctrines, with the initial practice of combined arms altering into Infantry and armour fighting separated battles. Other new developments included the practice of unit dispersal to hold key ground and to engage the enemy using temporary units known as Jock columns. The two themes are inter-linked and contribute fresh insights to the debate on British methods of warfare. The methodology has been to consult key primary documents, reports, war diaries and published memoirs, from major archives across the UK and compare these with the campaign historiography to develop the main arguments. These include the National Archives, the Churchill Archives Centre, the Liddell-Hart Centre for Military History, the National Army Museum, John Rylands Centre, Imperial War Museum at London and Duxford and London and the Tank Museum Archives at Bovington. The sources include unit war diaries, after action reports, along with many of the key 3 published and some unpublished memoirs. The analysis of these two themes will show that key terrain features were a significant influence upon all levels of military planning and operations throughout the campaign.