60 research outputs found
Pixelating Vector Art
Pixel art is a popular style of digital art often found in video games. It is typically characterized by its low resolution and use of limited colour palettes. Pixel art is created manually with little automation because it requires attention to pixel-level details. Working with individual pixels is a challenging and abstract task, whereas manipulating higher-level objects in vector graphics is much more intuitive. However, it is difficult to bridge this gap because although many rasterization algorithms exist, they are not well-suited for the particular needs of pixel artists, particularly at low resolutions. In this thesis, we introduce a class of rasterization algorithms called pixelation that is tailored to pixel art needs. We describe how our algorithm suppresses artifacts when pixelating vector paths and preserves shape-level features when pixelating geometric primitives. We also developed methods inspired by pixel art for drawing lines and angles more effectively at low resolutions. We compared our results to rasterization algorithms, rasterizers used in commercial software, and human subjects---both amateurs and pixel artists. Through formal analyses of our user study studies and a close collaboration with professional pixel artists, we showed that, in general, our pixelation algorithms produce more visually appealing results than na\"{i}ve rasterization algorithms do
Антиаліайзинг зображення кривих другого порядку, заданих загальним рівнянням
Запропоновано новий підхід до антиаліайзингу кривих другого порядку за умови, що вони задані загальним рівнянням. Метод характеризується простотою апаратної реалізації
A Human Body Modelling System for Motion Studies
The need to visualize and interpret human body movement data from experiments and simulations has led to the development of a new three-dimensional representation for the human body. Based on a skeleton of joints and segments, the model is manipulated by specifying joint positions with respect to arbitrary frames of reference. The external form is modelled as the union of overlapping spheres which define the surface of each segment. The properties of the segment and sphere model include: an ability to utilize any connected portion of the body in order to examine selected movements without computing movements of undesired parts, a naming mechanism for describing parts within a segment, and a collision detection algorithm for finding contacts or illegal intersections of the body with itself or other objects. Several display algorithms are possible, including inexpensive hidden surface removal. The spherical body model can also be easily combined with planar polygon object environments
Антиаліайзинг зображення кривих другого порядку заданих загальним рівнянням
The new approach is Offered to antialiayzing crooked second order provided that they are given by general equation. Method is characterized by simplicity to hardware realizationПредложен новый подход к антиалиайзингу кривых второго порядка при условии, что они заданы общим уравнением. Метод характеризуется простотой аппаратной реализацииЗапропоновано новий підхід до антиаліайзингу кривих другого порядку за умови, що вони задані загальним рівнянням. Метод характеризується простотою апаратної реалізаці
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Hardware accelerated computer graphics algorithms
The advent of shaders in the latest generations of graphics hardware, which has made consumer level graphics hardware partially programmable, makes now an ideal time to investigate new graphical techniques and algorithms as well as attempting to improve upon existing ones.
This work looks at areas of current interest within the graphics community such as Texture Filtering, Bump Mapping and Depth of Field simulation. These are all areas which have enjoyed much interest over the history of computer graphics but which provide a great deal of scope for further investigation in the light of recent hardware advances.
A new hardware implementation of a texture filtering technique, aimed at consumer level hardware, is presented. This novel technique utilises Fourier space image filtering to reduce aliasing. Investigation shows that the technique provides reduced levels of aliasing along with comparable levels of detail to currently popular techniques. This adds to the community's knowledge by expanding the range of techniques available, as well as increasing the number of techniques which offer the potential for easy integration with current consumer level graphics hardware along with real-time performance.
Bump mapping is a long-standing and well understood technique. Variations and extensions of it have been popular in real-time 3D computer graphics for many years. A new hardware implementation of a technique termed Super Bump Mapping (SBM) is introduced. Expanding on the work of Cant and Langensiepen [1], the SBM technique adopts the novel approach of using normal maps which supply multiple vectors per texel. This allows the retention of much more detail and overcomes some of the aliasing deficiencies of standard bump mapping caused by the standard single vector approach and the non-linearity of the bump mapping process.
A novel depth of field algorithm is proposed, which is an extension of the authors previous work [2][3][4]. The technique is aimed at consumer level hardware and attempts to raise the bar for realism by providing support for the 'see-through' effect. This effect is a vital factor in the realistic appearance of simulated depth of field and has been overlooked in real time computer graphics due to the complexities of an accurate calculation. The implementation of this new algorithm on current consumer level hardware is investigated and it is concluded that while current hardware is not yet capable enough, future iterations will provide the necessary functional and performance increases
The development of perceptual averaging: learning what to do, not just how to do it
The mature visual system condenses complex scenes into simple summary statistics (e.g., average size, location, orientation, etc.). However, children, often perform poorly on perceptual averaging tasks. Children's difficulties are typically thought to represent the suboptimal implementation of an adult-like strategy. This paper examines another possibility: that children actually make decisions in a qualitatively different way to adults (optimal implementation of a non-ideal strategy). Ninety children (6-7, 8-9, 10-11 years) and 30 adults were asked to locate the middle of randomly generated dot-clouds. Nine plausible decision strategies were formulated, and each was fitted to observers' trial-by-trial response data (Reverse Correlation). When the number of visual elements was low (N < 6), children used a qualitatively different decision strategy from adults: appearing to "join up the dots" and locate the gravitational center of the enclosing shape. Given denser displays, both children and adults used an ideal strategy of arithmetically averaging individual points. Accounting for this difference in decision strategy explained 29% of children's lower precision. These findings suggest that children are not simply suboptimal at performing adult-like computations, but may at times use sensible, but qualitatively different strategies to make perceptual judgments. Learning which strategy is best in which circumstance might be an important driving factor of perceptual development
Freehand Sketch Recognition for Computer-Assisted Language Learning of Written East Asian Languages
One of the challenges students face in studying an East Asian (EA) language
(e.g., Chinese, Japanese, and Korean) as a second language is mastering their selected
language’s written component. This is especially true for students with native fluency of
English and deficient written fluency of another EA language. In order to alleviate the
steep learning curve inherent in the properties of EA languages’ complicated writing
scripts, language instructors conventionally introduce various written techniques such as
stroke order and direction to allow students to study writing scripts in a systematic
fashion. Yet, despite the advantages gained from written technique instruction, the
physical presence of the language instructor in conventional instruction is still highly
desirable during the learning process; not only does it allow instructors to offer valuable
real-time critique and feedback interaction on students’ writings, but it also allows
instructors to correct students’ bad writing habits that would impede mastery of the
written language if not caught early in the learning process.
The current generation of computer-assisted language learning (CALL)
applications specific to written EA languages have therefore strived to incorporate
writing-capable modalities in order to allow students to emulate their studies outside the classroom setting. Several factors such as constrained writing styles, and weak feedback
and assessment capabilities limit these existing applications and their employed
techniques from closely mimicking the benefits that language instructors continue to
offer. In this thesis, I describe my geometric-based sketch recognition approach to
several writing scripts in the EA languages while addressing the issues that plague
existing CALL applications and the handwriting recognition techniques that they utilize.
The approach takes advantage of A Language to Describe, Display, and Editing in
Sketch Recognition (LADDER) framework to provide users with valuable feedback and
assessment that not only recognizes the visual correctness of students’ written EA
Language writings, but also critiques the technical correctness of their stroke order and
direction. Furthermore, my approach provides recognition independent of writing style
that allows students to learn with natural writing through size- and amount-independence,
thus bridging the gap between beginner applications that only recognize single-square
input and expert tools that lack written technique critique
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