There currently exist several techniques for selecting and combining images from a digital image library into a single image so that the result meets certain prespecified visual criteria. Image mosaic methods, first explored by Connors and Trivedi[18], arrange library images according to some tiling arrangement, often a regular grid, so that the combination of images, when viewed as a whole, resembles some input target image. Other techniques, such as Autocollage of Rother et al.[78], seek only to combine images in an interesting and visually pleasing manner, according to certain composition principles, without attempting to approximate any target image. Each of these techniques provide a myriad of creative options for artists who wish to combine several levels of meaning into a single image or who wish to exploit the meaning and symbolism contained in each of a large set of images through an efficient and easy process. We first examine the most notable and successful of these methods, and summarize the advantages and limitations of each. We then formulate a set of goals for an image collage system that combines the advantages of these methods while addressing and mitigating the drawbacks. Particularly, we propose a system for creating photocollages that approximate a target image as an aggregation of smaller images, chosen from a large library, so that interesting visual correspondences between images are exploited. In this way, we allow users to create collages in which multiple layers of meaning are encoded, with meaningful visual links between each layer. In service of this goal, we ensure that the images used are as large as possible and are combined in such a way that boundaries between images are not immediately apparent, as in Autocollage. This has required us to apply a multiscale approach to searching and comparing images from a large database, which achieves both speed and accuracy. We also propose a new framework for color post-processing, and propose novel techniques for decomposing images according to object and texture information.

Dendritic or branching structures are commonly seen in natural phenomena such as lightning, cracking and vegetal growth. They are also often used for artistic or decorative purposes, ranging from ornamentation to decorative ceramics. Existing procedural methods for modeling these structures remain very limited in terms of control and flexibility. As a result, these objects tend to be modeled individually, which is a painstaking and costly process.<p>We present a new procedural method for modeling dendritic structures based on a path planning approach. Our method includes the implementation of a partial non-scalar distance metric that gives us effective and flexible control handles over the evolving dendritic structure. These control handles are demonstrated by guiding the growth of dendritic structures using input images, allowing us to create a form of stylistic dendritic halftoning and to embed hidden images in dendritic trees to create pareidolia effects. These applications demonstrate the vast diversity of structures that can easily be modeled by our process a flexibility that existing methods definitely lack. We also demonstrate the application of the partial non-scalar distance metric to the context of texture synthesis from example, and show how it holds promise for many other contexts.

Realistic computer generated images are computed by combining geometric effects, reflectance models for several captured and phenomenological materials, and real-world lighting according to mathematical models of physical light transport. Several important lighting phenomena should be considered when targeting realistic image simulation. A combination of soft and hard shadows, which arise from the interaction of surface and light geometries, provide necessary shape perception cues for a viewer. A wide variety of realistic materials, from physically-captured reflectance datasets to empirically designed mathematical models, modulate the virtual surface appearances in a manner that can further dissuade a viewer from considering the possibility of computational image synthesis over that of reality. Lastly, in many important cases, light reflects off many different surfaces before entering the eye. These secondary effects can be critical in grounding the viewer in a virtual world, since the human visual system is adapted to the physical world, where such effects are constantly in play. Simulating each of these effects is challenging due to their individual underlying complexity. The net complexity is compounded when several effects are combined. This thesis will investigate real-time approaches for simulating these effects under stringent performance and memory constraints, and with varying degrees of interactivity. In order to make these computations tractable given these added constraints, I will use data and signal analysis techniques to identify predictable patterns in the different spatial and angular signals used during image synthesis. The results of this analysis will be exploited with several analytic and data-driven mathematical models that are both efficient, and yield accurate approximations with predictable and controllable error.

In this thesis, we present a detailed analysis of the conventions that appear in fictional spaceship design, including a discussion of their origins, their uses in emulating certain traits, and reasons these conventions might be followed or ignored. We uncover these conventions by examining and comparing popular spaceship designs from the past sixty years, which we present in a detailed survey. We also examine an aesthetic interpretation of information theory, which can be used to describe the balance of uniformity amidst variety, and discuss specific strategies for incorporating these principles into the creation of spaceship surface details. Procedural modeling describes a set of techniques used to allow computers to generate digital content such as 3D digital models automatically. However, procedural modeling to date has focused on very specific areas: natural scenery such as trees and terrain, or cityscapes such as road maps and buildings. While these types of models are important and useful, they focus on a specific subset of the procedural modeling problem. Though procedural generation can be an invaluable tool for providing viable and dynamic content, it is troubling that so few types of objects have been studied in this area. Using the aesthetic and spaceship principles we define, we have developed a prototype system to procedurally generate the surface details of a large scale spaceship. Given a surface representing the frame of a spaceship, we apply geometry automatically in a coherent manner to achieve the appearance of a spaceship by emulating important traits.

Automated warehouses are frequently used within the industry. SQL databases are often used for storing various kinds of information about stored items, including their physical positions in the warehouse with respect to X, Y and Z positions. Benefits of this includes savings in working time, optimization of storage capability and – most of all – increased employee safety. IT services company Sogeti’s office in Karlstad has been looking into a project on behalf of one of their customers to implement this kind of automated warehouse. In the pilot study of this project, ideas of a three-dimensional graphic visualization of the warehouse and its stored contents have come up. This kind of tool would give a warehouse operator a clear overview of what is currently in store, as well as quick access to various pieces of information about each and every item in store. Also, in a wider perspective, other types of warehouses and storage areas could benefit from this kind of tool. During the course of this project, a graphical visualization tool for this purpose was developed, resulting in a product that met a significant part of the initial requirements.

Current Graphic Processing Units (GPUs) (circa. 2003/2004) have programmable vertex and fragment units. Often these units are implemented as SIMD processors employing parallel pipelines. Data dependent conditional execution on SIMD architectures implemented using processor idling is inefficient. I propose a multi-pass approach based on conditional streams which allows dynamic load balancing of the fragment units of the GPU and better theoretical performance on programs using data dependent conditionals and loops. The proposed system can be used to turn the fragment unit of a SIMD GPU into a stream processor with data dependent control flow.

In this thesis, we present a detailed analysis of the conventions that appear in fictional spaceship design, including a discussion of their origins, their uses in emulating certain traits, and reasons these conventions might be followed or ignored. We uncover these conventions by examining and comparing popular spaceship designs from the past sixty years, which we present in a detailed survey. We also examine an aesthetic interpretation of information theory, which can be used to describe the balance of uniformity amidst variety, and discuss specific strategies for incorporating these principles into the creation of spaceship surface details. Procedural modeling describes a set of techniques used to allow computers to generate digital content such as 3D digital models automatically. However, procedural modeling to date has focused on very specific areas: natural scenery such as trees and terrain, or cityscapes such as road maps and buildings. While these types of models are important and useful, they focus on a specific subset of the procedural modeling problem. Though procedural generation can be an invaluable tool for providing viable and dynamic content, it is troubling that so few types of objects have been studied in this area. Using the aesthetic and spaceship principles we define, we have developed a prototype system to procedurally generate the surface details of a large scale spaceship. Given a surface representing the frame of a spaceship, we apply geometry automatically in a coherent manner to achieve the appearance of a spaceship by emulating important traits.

Direct interaction in virtual environments can be realized using relatively simple hardware, such as standard webcams and monitors. The result is a large gap between the stimuli existing in real-world interactions and those provided in the virtual environment. This leads to reduced efficiency and effectiveness when performing tasks. Conceivably these missing stimuli might be supplied through a visual modality, using sensory substitution. This work suggests a display technique that attempts to usefully and non-detrimentally employ sensory substitution to display proximity, tactile, and force information. We solve three problems with existing feedback mechanisms. Attempting to add information to existing visuals, we need to balance: not occluding the existing visual output; not causing the user to look away from the existing visual output, or otherwise distracting the user; and displaying as much new information as possible. We assume the user interacts with a virtual environment consisting of a manually controlled probe and a set of surfaces. Our solution is a pseudo-shadow: a shadow-like projection of the user's probe onto the surface being explored or manipulated. Instead of drawing the probe, we only draw the pseudo-shadow, and use it as a canvas on which to add other information. Static information is displayed by varying the parameters of a procedural texture rendered in the pseudo-shadow. The probe velocity and probe-surface distance modify this texture to convey dynamic information. Much of the computation occurs on the GPU, so the pseudo-shadow renders quickly enough for real-time interaction. As a result, this work contains three contributions: a simple collision detection and handling mechanism that can generalize to distance-based force fields; a way to display content during probe-surface interaction that reduces occlusion and spatial distraction; and a way to visually convey small-scale tactile texture.

Dendritic or branching structures are commonly seen in natural phenomena such as lightning, cracking and vegetal growth. They are also often used for artistic or decorative purposes, ranging from ornamentation to decorative ceramics. Existing procedural methods for modeling these structures remain very limited in terms of control and flexibility. As a result, these objects tend to be modeled individually, which is a painstaking and costly process.<p>We present a new procedural method for modeling dendritic structures based on a path planning approach. Our method includes the implementation of a partial non-scalar distance metric that gives us effective and flexible control handles over the evolving dendritic structure. These control handles are demonstrated by guiding the growth of dendritic structures using input images, allowing us to create a form of stylistic dendritic halftoning and to embed hidden images in dendritic trees to create pareidolia effects. These applications demonstrate the vast diversity of structures that can easily be modeled by our process a flexibility that existing methods definitely lack. We also demonstrate the application of the partial non-scalar distance metric to the context of texture synthesis from example, and show how it holds promise for many other contexts.

There currently exist several techniques for selecting and combining images from a digital image library into a single image so that the result meets certain prespecified visual criteria. Image mosaic methods, first explored by Connors and Trivedi[18], arrange library images according to some tiling arrangement, often a regular grid, so that the combination of images, when viewed as a whole, resembles some input target image. Other techniques, such as Autocollage of Rother et al.[78], seek only to combine images in an interesting and visually pleasing manner, according to certain composition principles, without attempting to approximate any target image. Each of these techniques provide a myriad of creative options for artists who wish to combine several levels of meaning into a single image or who wish to exploit the meaning and symbolism contained in each of a large set of images through an efficient and easy process. We first examine the most notable and successful of these methods, and summarize the advantages and limitations of each. We then formulate a set of goals for an image collage system that combines the advantages of these methods while addressing and mitigating the drawbacks. Particularly, we propose a system for creating photocollages that approximate a target image as an aggregation of smaller images, chosen from a large library, so that interesting visual correspondences between images are exploited. In this way, we allow users to create collages in which multiple layers of meaning are encoded, with meaningful visual links between each layer. In service of this goal, we ensure that the images used are as large as possible and are combined in such a way that boundaries between images are not immediately apparent, as in Autocollage. This has required us to apply a multiscale approach to searching and comparing images from a large database, which achieves both speed and accuracy. We also propose a new framework for color post-processing, and propose novel techniques for decomposing images according to object and texture information.