438 research outputs found

    An investigation of hair modelling and rendering techniques with emphasis on African hairstyles

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    Many computer graphics applications make use of virtual humans. Methods for modelling and rendering hair are needed so that hairstyles can be added to the virtual humans. Modelling and rendering hair is challenging due to the large number of hair strands and their geometric properties, the complex lighting effects that occur among the strands of hair, and the complexity and large variation of human hairstyles. While methods have been developed for generating hair, no methods exist for generating African hair, which differs from hair of other ethnic groups. This thesis presents methods for modelling and rendering African hair. Existing hair modelling and rendering techniques are investigated, and the knowledge gained from the investigation is used to develop or enhance hair modelling and rendering techniques to produce three different forms of hair commonly found in African hairstyles. The different forms of hair identified are natural curly hair, straightened hair, and braids or twists of hair. The hair modelling techniques developed are implemented as plug-ins for the graphics program LightWave 3D. The plug-ins developed not only model the three identified forms of hair, but also add the modelled hair to a model of a head, and can be used to create a variety of African hairstyles. The plug-ins significantly reduce the time spent on hair modelling. Tests performed show that increasing the number of polygons used to model hair increases the quality of the hair produced, but also increases the rendering time. However, there is usually an upper bound to the number of polygons needed to produce a reasonable hairstyle, making it feasible to add African hairstyles to virtual humans. The rendering aspects investigated include hair illumination, texturing, shadowing and antialiasing. An anisotropic illumination model is developed that considers the properties of African hair, including the colouring, opacity and narrow width of the hair strands. Texturing is used in several instances to create the effect of individual strands of hair. Results show that texturing is useful for representing many hair strands because the density of the hair in a texture map does not have an effect on the rendering time. The importance of including a shadowing technique and applying an anti-aliasing method when rendering hair is demonstrated. The rendering techniques are implemented using the RenderMan Interface and Shading Language. A number of complete African hairstyles are shown, demonstrating that the techniques can be used to model and render African hair successfully.GNU Ghostscript 7.0

    A hybrid hair model using three dimensional fuzzy textures

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    Cataloged from PDF version of article.Human hair modeling and rendering have always been a challenging topic in computer graphics. The techniques for human hair modeling consist of explicit geometric models as well as volume density models. Recently, hybrid cluster models have also been successful in this subject. In this study, we present a novel three dimensional texture model called 3D Fuzzy Textures and algorithms to generate them. Then, we use the developed model along with a cluster model to give human hair complex hairstyles such as curly and wavy styles. Our model requires little user effort to model curly and wavy hair styles. With this study, we aim at eliminating the drawbacks of the volume density model and the cluster hair model with 3D fuzzy textures. A three dimensional cylindrical texture mapping function is introduced for mapping purposes. Current generation graphics hardware is utilized in the design of rendering system enabling high performance rendering.Aran, Medeni ErolM.S

    Image-Based Approaches to Hair Modeling

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    Hair is a relevant characteristic of virtual characters, therefore the modeling of plausible facial hair and hairstyles is an essential step in the generation of computer generated (CG) avatars. However, the inherent geometric complexity of hair together with the huge number of filaments of an average human head make the task of modeling hairstyles a very challenging one. To date this is commonly a manual process which requires artist skills or very specialized and costly acquisition software. In this work we present an image-based approach to model facial hair (beard and eyebrows) and (head) hairstyles. Since facial hair is usually much shorter than the average head hair two different methods are resented, adapted to the characteristics of the hair to be modeled. Facial hair is modeled using data extracted from facial texture images and missing information is inferred by means of a database-driven prior model. Our hairstyle reconstruction technique employs images of the hair to be modeled taken with a thermal camera. The major advantage of our thermal image-based method over conventional image-based techniques lies on the fact that during data capture the hairstyle is "lit from the inside": the thermal camera captures heat irradiated by the head and actively re-emitted by the hair filaments almost isotropically. Following this approach we can avoid several issues of conventional image-based techniques, like shadowing or anisotropy in reflectance. The presented technique requires minimal user interaction and a simple acquisition setup. Several challenging examples demonstrate the potential of the proposed approach

    Hairstyle modelling based on a single image.

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    Hair is an important feature to form character appearance in both film and video game industry. Hair grooming and combing for virtual characters was traditionally an exclusive task for professional designers because of its requirements for both technical manipulation and artistic inspiration. However, this manual process is time-consuming and further limits the flexibility of customised hairstyle modelling. In addition, it is hard to manipulate virtual hairstyle due to intrinsic hair shape. The fast development of related industrial applications demand an intuitive tool for efficiently creating realistic hairstyle for non-professional users. Recently, image-based hair modelling has been investigated for generating realistic hairstyle. This thesis demonstrates a framework Struct2Hair that robustly captures a hairstyle from a single portrait input. Specifically, the 2D hair strands are traced from the input with the help of image processing enhancement first. Then the 2D hair sketch of a hairstyle on a coarse level is extracted from generated 2D hair strands by clustering. To solve the inherently ill-posed single-view reconstruction problem, a critical hair shape database has been built by analysing an existing hairstyle model database. The critical hair shapes is a group of hair strands which possess similar shape appearance and close space location. Once the prior shape knowledge is prepared, the hair shape descriptor (HSD) is introduced to encode the structure of the target hairstyle. The HSD is constructed by retrieving and matching corresponding critical hair shape centres in the database. The full-head hairstyle is reconstructed by uniformly diffusing the hair strands on the scalp surface under the guidance of extracted HSD. The produced results are evaluated and compared with the state-of-the-art image based hair modelling methods. The findings of this thesis lead to some promising applications such as blending hairstyles to populate novel hair model, editing hairstyle (adding fringe hair, curling and cutting/extending hairstyle) and a case study of Bas-relief hair modelling on pre-processed hair images

    A general study of Minoan frescoes with particular reference to unpublished wall painting from Knossos

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    PhD ThesisThis four-part dissertation considers Minoan frescoes in their own right for a first time, with reference to unpublished paintings and nearly fifty new restorations, with a view to providing a new basis for historical reconstruction drawn from that source. Earliest developments begin with Neolithic architectural muse of mud plasters, the first painted plasters occuring in EM II settlements and simple decorative schemes in the First Palaces (1900-1700 B.C.). The sudden rise of pictorial naturalism in MM IIIA is explained by native cultural developments of the First Palace Period, not by foreign influences or "eideticism" which is rejected altogether. A review of the motival repertory leads to considerations of six main "cycles of ideas" whence the painters derived their themes. The most important, confined to Knossos palace, depicts a major festival of grand processions and athletic activities before the chief Minoan goddess, and it illuminates the palatial architechural design. But five different systems of mural decoration characterise Minoan architecture as a whole, with regional and perhaps autonomous variations at Cycadic sites. Technical considerations confirm "buon fresco" as the normal painting technique and distinguish Knossian town house and palace murals in construction and purpose. Similar distinctions in compositional design are also described. A review of eleven "schools" of Knossian painters and of regional artists precedes a detailed reconstruction of the dates of the frescoes on stratigraphical, stylistic and comparative evidence. Sir Arthur Evans's fresco dating should generally be lowered by one Minoan phase. Minoan pictorial painting ceases with the palace destruction at Knossos, c.1375 B.C. Major differences appear between pre- and post-LM IB frescoes, tentatively explained on the evidence of Aegean and Egyption pictorial representations by the arrival at Knossos of a Mycenaean military dynasty, c.1450 B.C. Minoan wall painting finally disappeared in the LM IIIB period

    TEACHERS’ PERCEPTIONS OF DEVIANT BEHAVIOURS PREVALENCE IN SENIOR SECONDARY SCHOOLS IN MAINLAND ZONE TWO, LAGOS.

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    Deviant behaviours in schools are behaviours that do not conform to the school norms, culture, rules and regulations. This study is about the teachers’ perceptions of the prevalence of deviant behaviours among the senior secondary two students in mainland zone two. The target population was all the senior secondary teachers in Mainland zone two, with 128 males and 152 female teachers. Data was collected using a self-structured questionnaire divided into two sections. Section A comprises the demographic data, while section B has 16 items. The items had subheadings, namely deviancies due to attack on school authority, deviancies relating to attacks on persons or properties, deviancies due to student’s gang attacks and deviancies relating to the poor reading study. The study was guided by one research question and two hypotheses. Mean and standard deviations were used to analyse the data while t-testing the null hypothesis at a 0.05 level of significance. Results showed no statistically significant difference between the perceptions of male and female teachers on the prevalence of deviant behaviours in schools. Still, there was a statistically significant difference in perception based on teachers’ age group. Recommendations were made, including provisions for counsellors, and regular seminars/workshops on deviant behaviours to students, school authorities, teachers and parents

    Realistic Hair Simulation: Animation and Rendering

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    International audienceThe last five years have seen a profusion of innovative solutions to one of the most challenging tasks in character synthesis: hair simulation. This class covers both recent and novel research ideas in hair animation and rendering, and presents time tested industrial practices that resulted in spectacular imagery

    TEACHERS’ PERCEPTIONS OF DEVIANT BEHAVIOURS PREVALENCE IN SENIOR SECONDARY SCHOOLS IN MAINLAND ZONE TWO, LAGOS.

    Get PDF
    Deviant behaviours in schools are behaviours that do not conform to the school norms, culture, rules and regulations. This study is about the teachers’ perceptions of the prevalence of deviant behaviours among the senior secondary two students in mainland zone two. The target population was all the senior secondary teachers in Mainland zone two, with 128 males and 152 female teachers. Data was collected using a self-structured questionnaire divided into two sections. Section A comprises the demographic data, while section B has 16 items. The items had subheadings, namely deviancies due to attack on school authority, deviancies relating to attacks on persons or properties, deviancies due to student’s gang attacks and deviancies relating to the poor reading study. The study was guided by one research question and two hypotheses. Mean and standard deviations were used to analyse the data while t-testing the null hypothesis at a 0.05 level of significance. Results showed no statistically significant difference between the perceptions of male and female teachers on the prevalence of deviant behaviours in schools. Still, there was a statistically significant difference in perception based on teachers’ age group. Recommendations were made, including provisions for counsellors, and regular seminars/workshops on deviant behaviours to students, school authorities, teachers and parents

    Data Analytics and Visualization for Virtual Simulation

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    Healthcare organizations attract a diversity of caregivers and patients by providing essential care. While interacting with people of various races, ethnicity, and economical background, caregivers need to be empathetic and compassionate. Proper training and exposure are needed to understand the patient’s background and handle different situations and provide the best care for the patient. With social determinants of health (SDOH) as the basis, the thesis focuses on providing exposure through “Wright LIFE (Lifelike Immersion for Equity) - A simulation-based training tool” to two such scenarios covering patients from the LGBTQIA+ community & autism spectrum disorder (ASD). This interactive tool helps to create mindfulness about the social and economic disparities faced by the patients through realistic and captivating gameplay. Though the primary focus of the “Wright LIFE” application is “Digital Learning”, it would help to understand how effective the application is in terms of improving the provider\u27s abilities. Through statistical evidence, the tool can be improved, which in turn will improve the user experience. For this analysis, during the simulation, we also focus on collecting the data gathered from the participants through surveys. The simulation includes different questionnaires where participants can provide feedback at various stages within the simulation. This then allows for a comparison between the participants’ responses to see the rate of improvement as a result of the simulation. To analyze the data from the participant\u27s responses, data analysis, and visualization tools help to represent the data using charts, infographics, animations, and many more to assist this in this analytic process. The analysis of the data can help to understand the trend of the participants’ responses to the questionnaire. The goal of the questionnaire is to collect participants’ responses to assess anxiety, frustration, and compassion levels pre- and post-simulation. A comparative analysis is then performed. This analysis shows that the provider’s anxiety and frustration decreased after the simulation whereas the compassion increased. This is an indication that the simulation can improve the provider’s experience while working with patients with biases. The data also helped to identify the users who actively participated in the survey based on demographic data like gender, profession, experience, and age. “A picture is worth a thousand words”. Through visualization, we can bring the data to life and provide a clear idea of what the data represents by giving visual context. Tableau is used for visualizing the survey data collected from the “SDOH” simulation consisting of responses from the providers before and after the interaction with the patients. The visualizations transform the raw data into simple and informative graphs to understand the behavioral trends and to check how the providers respond to the stories in the simulations. This allows us to determine the effectiveness of the simulation more efficiently

    Human Skin Modelling and Rendering

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    Creating realistic-looking skin is one of the holy grails of computer graphics and is still an active area of research. The problem is challenging due to the inherent complexity of skin and its variations, not only across individuals but also spatially and temporally among one. Skin appearance and reflectance vary spatially in one individual depending on its location on the human body, but also vary temporally with the aging process and the body state. Emotions, health, physical activity, and cosmetics for example can all affect the appearance of skin. The spatially varying reflectance of skin is due to many parameters, such as skin micro- and meso-geometry, thickness, oiliness, and pigmentation. It is therefore a daunting task to derive a model that will include all these parameters to produce realistic-looking skin. The problem is also compounded by the fact that we are very well accustomed to the appearance of skin and especially sensitive to facial appearances and expressions. Skin modelling and rendering is crucial for many applications such as games, virtual reality, films, and the beauty industry, to name a few. Realistic-looking skin improves the believability and realism of applications. The complexity of skin makes the topic of skin modelling and rendering for computer graphics a very difficult, but highly stimulating one. Skin deformations and biomechanics is a vast topic that we will not address in this dissertation. We rather focus our attention on skin optics and present a simple model for the reflectance of human skin along with a system to support skin modelling and rendering
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