Current Automatic Palmprint Identification Systems (APIS) closely follow the matching philosophy of Automatic Fingerprint Identification Systems (AFIS), in that they exclusively use a small subset of Level II palmar detail, when matching a latent to an exemplar palm print. However, due the increased size and the significantly more complex structure of the palm, it has long been recognised that there is much detail that remains underutilised. Forensic examiners routinely use this additional information when manually matching latents. The thesis develops novel automatic feature extraction and matching methods which exploit the underutilised Level I detail contained in the friction ridge flow. When applied to a data base of exemplars, the approach creates a ranked list of matches. It is shown that the matching success rate varied with latent size. For latents of diameter 38mm, 91:1% were ranked first and 95:6% of the matches were contained within the ranked top 10. The thesis presents improved orientation field extraction methods which are optimised for friction ridge flow and novel enhancement techniques, based upon the novel use of local circular statistics on palmar orientation fields. In combination, these techniques are shown to provide a more accurate orientation estimate than previous work. The novel feature extraction stages exploit the level sets of higher order local circular statistics, which naturally segment the palm into homogeneous regions representing Level I detail. These homogeneous regions, characterised by their spatial and circular features, are used to form a novel compact tree-like hierarchical representation of the Level I detail. Matching between the latent and an exemplar is performed between their respective tree-like hierarchical structures. The methods developed within the thesis are complementary to current APIS techniques.

Simulation of modern battlefield scenarios on consumer PC:s deal with a number of limitations, many of them related to the limited performance of a normal PC compared to workstations and servers. Specifically, the visualization of realistic large scale outdoor environments is problematic because of the large amount of data required to describe its contents. This becomes especially problematic in simulations of fast moving vehicles such as aircrafts, where one needs to maintain high frame rates while having high visual detail for orientation and targeting. This thesis proposes a method of generating realistic outdoor environments from actual geological data and then rendering it efficiently using an improved level of detail algorithm within a proprietary battle simulation framework. We also show how to integrate an open source Flight Dynamics Model (FDM) into the simulation framework for future hybrid simulations involving aircrafts.

Context. Collision is a basic necessity in most simulated environments, especially video games, which demand user interaction. Octrees are a way to divide the simulated environments into smaller, more manageable parts,and is a hierarchical tree-structure, where each node has eight children. Octrees and similar tree-structural methods have been used frequently to optimize collision calculations and partition the objects in the 3D space. Objectives. The aim of this thesis is to find a way to further improve upon the octree structure, by using a two-level octree structure, and simplify the collision of objects that do not demand much complexity, due to their size or the geometric simplicity of their 3D models, this is done by calculating how many pixels the objects occupy on the screen, and use that as a factor when deciding the depth of their individual octrees. Methods. Each object in the 3D environment is divided using an octree. These octrees generated for the objects are then placed in a larger octree. This large octree use the smaller ones to check collision between the objects. The pixel area occupied on the screen by the objects’ octrees is used to determine what depth of the octrees will be check for intersection. Two test scenes were set up to test our model. Results. Our implementation could effectively reduce the depth of octrees belonging to objects occupying little space on the screen. The experiments also showed that the reduced depth could be used with only a slight loss in accuracy. The accuracy loss increased when more objects were used. Conclusions. The results gained in the thesis show that the pixel area can be used effectively, and the simplified octrees can still represent the objects adequately, resulting in a cheaper but slightly less accurate collision.

Denna rapport presenterar ett alternativt sätt att ljussätta terräng i datorgrafik. Tidigare modeller har vanligtvis byggt på lokal ljussättning, som inte tar hänsyn till kringliggande geometri, och har med en extra process approximerat effekten av ljusinteraktionen. Genom att använda sig av en teknik som kallas precomputed radiance transfer (PRT) kan man förberäkna hur en punkt interagerar med ljus för olika inkommande riktningar och undviker därmed att göra detta under programkörningen. Det är viktigt att denna teknik även fungerar tillsammans med level-of-detail (LOD) terrängrenderingsalgoritmer eftersom rendering av alla trianglar i terrängen för varje skärmuppdatering inte är optimalt för dagens grafikkort. Man vill därför representera den underliggande terrängen med fler trianglar närmare betraktaren och färre längre bort. Motiveringen till detta är att trianglar längre ifrån betraktaren kommer resultera i färre pixlar på skärmen, så att rendera större trianglar gör en liten visuell skillnad. Arbetet visar på att tekniken fungerar med LOD-terrängrenderingsalgoritmer med bra prestanda och visuell kvalitet.

This thesis is focused on the improvement of an existing implementation of a waveform visualizer. The problem area handled in this work has its focus on how to reduce the number of points to be plotted. The given waveform visualizer was extended by the use of two additional algorithms. First, a Level Of Detail (LOD) algorithm that gives the subset of points that are necessary to plot the waveform in the current zoom level. Second, a straight line identification algorithm to find a series of points aligned in a straight line, only leaving the end points and then drawing a line between them. These two optimizations are the main focus of this work.Additionally, an exporting functionality was implemented to export the plot data into several different data formats. Also some improvements of zooming, panning, some GUI design, and a new drag and drop functionality was constructed.

Context. Triangulated irregular network (TIN) can produce terrain meshes with a reduced triangle count compared to a regular grid. At the same time, TIN meshes are more challenging to optimize in real-time in comparison to other approaches. Objectives. This thesis explores efficient generation of view-dependent, adaptive TIN meshes for terrain during runtime with no or minimal preprocessing. Methods. Since the workings of the proposed technique is a novel approach, an empirical strategy was employed to present the findings instead of partial comparisons to related techniques. Results. To determine the result of the technique, run-time performance is measured and presented to provide incentives for implementation and improvements on the proposed algorithm. Several problem sizes are tested with varying terrain features to determine the effectiveness as a result of the features in the mesh.  Conclusions. We conclude that reducing the problem of mesh simplification to that of 2D Delaunay triangulation on sampled points spanning terrains is valid approach for triangulating on-the-fly. Moreover, this approach opens up for further improvements which may soon allow real-time triangulation of TINs.

The representation of 3D polygonal model on several levels of available detail is a problem inherent in the process of rendering a scene. Highly-detailed models, if placed far from the camera, suffer from spatial aliasing that results from inadequate sampling of their surface, and require disproportionately large amount of time to render. Low-detailed models on the other hand reduce the visual quality of the scene when placed too near to the camera. This report delves in both the theory and the practical techniques used for solving these problems. It describes various published solutions and the principles behind them, and presents a design and an implementation of selected techniques for the GPUEngine library.

The representation of 3D polygonal model on several levels of available detail is a problem inherent in the process of rendering a scene. Highly-detailed models, if placed far from the camera, suffer from spatial aliasing that results from inadequate sampling of their surface, and require disproportionately large amount of time to render. Low-detailed models on the other hand reduce the visual quality of the scene when placed too near to the camera. This report delves in both the theory and the practical techniques used for solving these problems. It describes various published solutions and the principles behind them, and presents a design and an implementation of selected techniques for the GPUEngine library.

Background. Shadow mapping is a method that is used for generating and imitating shadows in 3D-spaces. This technique has been used in the entertainment media industry in the form of games, movies and 3D renderings of environments to create a more realistic experience for consumers. Shadow mapping is not a perfect technique, and is performance costing on the GPU; however, some methods save performance by reducing the complexity of geometrical shapes and textures depending on the distance between observer and object. These techniques are based on that the observer will not notice the complexity reductions; can the usage of such methods be extended to textures covered in shadows without any consequences in the aspect of visual appearance and preference? Objectives. This thesis aims to examine if there is a possibility to extend the usage of LOD techniques to shadowed textures and to analyze individuals’ preferences of texture variants that are covered in shadows. Additionally, proposing the method of lowering texture resolution by using DirectX:s sampler data type, which is configurable to increase the level of details with mipmapping when sampling textures. Methods. This document presents a user study using the Two-alternative forced choice method and PsychoPy application to create a visual test. The visual test was conducted in a controlled and observed environment with volunteering participants. The objective of the visual test was to go through several sets of different images, and to choose which image of each set that was preferred. The stimulus was repeated with the initial images fading in and out slowly to prevent carry over effects. After the test participants were asked to fill out a questionnaire. The questionnaire assessed if they noticed any differences within the shadows, and if they had any additional thoughts about the experiment. Results. The results from the study were then evaluated through a binomial test that yielded that there was no statistically significant difference in preference between the lowered texture resolution in shadows and normal texture resolution in shadows. Separately evaluating the environments showed that there was a preference for shadowed low-resolution textures in environments that were dark. The environments with high illumination had more varied results. There were 17 participants that volunteered in the test and were ranging from the ages 18 to 29. Conclusions. With the results presented it was shown that the shadowed lowresolution textures were preferred in environments with low illumination. This suggests that the proposed concept method is better suited for similar environments. However, several factors may have affected the results. Factors such as images being too dark, the lack of exaggerated images, images fading in and out too fast, few participants, more partaking will assure there is less chance for bias.

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