Recursos alternativos de expresión

La mayoría de las imágenes no representan solamente propiedades visuales de una escena; no son siempre una simple proyección unidireccional de una escena 3D a una descripción bidimensional. Una imagen puede tener como propósito el transmitir un mensaje: educativo, estético, emocional, etc. Como resultado, el destino final de una imagen establece restricciones en la generación de la misma, en términos de claridad, representación de sus cualidades, su plasmado en 2D, etc. El arte y oficio de crear una gráfica procura optimizar el resultado final acorde con un fin, bajo ciertas restricciones establecidas por el medio, el contexto social, el estilo artístico, etc.. Se podría redefinir el proceso de generación de una imagen como un problema de optimización que tiene como objetivo producir la mejor representación gráfica para un propósito en particular. A su vez, todo proceso de optimización involucra una retroalimentación de información. Es de importancia, entonces, el estudio e incorporación al proceso de generación de una imagen del uso de diferentes métodos, técnicas, medios, o combinaciones de ellos, que favorezcan el proceso de optimización. Y en consecuencia, la especificación de un marco contextual asociado al nuevo proceso.1Eje: Visualización y Computación gráficaRed de Universidades con Carreras en Informática (RedUNCI

Recursos alternativos de expresión

La mayoría de las imágenes no representan solamente propiedades visuales de una escena; no son siempre una simple proyección unidireccional de una escena 3D a una descripción bidimensional. Una imagen puede tener como propósito el transmitir un mensaje: educativo, estético, emocional, etc. Como resultado, el destino final de una imagen establece restricciones en la generación de la misma, en términos de claridad, representación de sus cualidades, su plasmado en 2D, etc. El arte y oficio de crear una gráfica procura optimizar el resultado final acorde con un fin, bajo ciertas restricciones establecidas por el medio, el contexto social, el estilo artístico, etc.. Se podría redefinir el proceso de generación de una imagen como un problema de optimización que tiene como objetivo producir la mejor representación gráfica para un propósito en particular. A su vez, todo proceso de optimización involucra una retroalimentación de información. Es de importancia, entonces, el estudio e incorporación al proceso de generación de una imagen del uso de diferentes métodos, técnicas, medios, o combinaciones de ellos, que favorezcan el proceso de optimización. Y en consecuencia, la especificación de un marco contextual asociado al nuevo proceso.1Eje: Visualización y Computación gráficaRed de Universidades con Carreras en Informática (RedUNCI

Recursos alternativos de expresión

La mayoría de las imágenes no representan solamente propiedades visuales de una escena; no son siempre una simple proyección unidireccional de una escena 3D a una descripción bidimensional. Una imagen puede tener como propósito el transmitir un mensaje: educativo, estético, emocional, etc. Como resultado, el destino final de una imagen establece restricciones en la generación de la misma, en términos de claridad, representación de sus cualidades, su plasmado en 2D, etc. El arte y oficio de crear una gráfica procura optimizar el resultado final acorde con un fin, bajo ciertas restricciones establecidas por el medio, el contexto social, el estilo artístico, etc.. Se podría redefinir el proceso de generación de una imagen como un problema de optimización que tiene como objetivo producir la mejor representación gráfica para un propósito en particular. A su vez, todo proceso de optimización involucra una retroalimentación de información. Es de importancia, entonces, el estudio e incorporación al proceso de generación de una imagen del uso de diferentes métodos, técnicas, medios, o combinaciones de ellos, que favorezcan el proceso de optimización. Y en consecuencia, la especificación de un marco contextual asociado al nuevo proceso.1Eje: Visualización y Computación gráficaRed de Universidades con Carreras en Informática (RedUNCI

Expressive rendering of mountainous terrain

technical reportPainters and cartographers have developed artistic landscape rendering techniques for centuries. Such renderings can visualize complex three-dimensional landscapes in a pleasing and understandable way. In this work we examine a particular type of artistic depiction, panorama maps, in terms of function and style, and we develop methods to automatically generate panorama map reminiscent renderings from GIS data. In particular, we develop image-based procedural surface textures for mountainous terrain. Our methods use the structural information present in the terrain and are developed with perceptual metrics and artistic considerations in mind

Digital facial engraving

This contribution introduces the basic techniques for digital facial engraving, which imitates traditional copperplate engraving. Inspired by traditional techniques, we first establish a set of basic rules thanks to which separate engraving layers are built on the top of the original photo. Separate layers are merged according to simple merging rules and according to range shift/scale masks specially introduced for this purpose. We illustrate the introduced technique by a set of black/white and color engravings, showing different features such as engraving-specific image enhancements, mixing different regular engraving lines with mezzotint, irregular perturbations of engraving lines etc. We introduce the notion of engraving style which comprises a set of separate engraving layers together with a set of associated range shift/scale masks. The engraving style helps to port the look and feel of one engraving to another. Once different libraries of pre-defined mappable engraving styles and an appropriate user interface are added to the basic system, producing a decent gravure starting from a simple digital photo will be a matter of seconds. The engraving technique described in this contribution opens new perspectives for digital art, adding unprecedented power and precision to the engraver's work

Beyond factual to formulated silhouettes

When sketching terrain, a view-dependent framework of silhouette-related cues is required. This framework is prominent in manual sketches and is especially important in small-scale depictions viewed obliquely from above. Occluding contours, namely the lines delineating depth discontinuities in the projected surface, are insufficient for forming this framework. The role which the occluding contour, or Factual Silhouette, plays in structuring the sketch becomes increasingly minimal as more of the terrain becomes visible, as the viewpoint is raised.The aim of this research is to extend the set of occluding contours to encompass situations that are perceived as causing an occlusion and would therefore be sketched in a similar manner. These locations, termed Formulated Silhouettes supplement the set of occluding contours and provide a successful structuring framework. The proposed method processes visible areas of terrain, which are turning away from view, to extract a classified, vector-based description for a given view of a Digital Elevation Model. Background approaches to silhouette rendering are reviewed and the specific contributions of this thesis are discussed.The method is tested using case studies composed of terrain of varying scale and character and two application studies demonstrate how silhouettes can be used to enhance existing terrain visualization techniques, both abstract and realistic. In addition, consultation with cartographic designers provides external verification of the research. The thesis concludes by noting how silhouette contours relate to perceived entities rather than actual occlusions

Classic Mosaics and Visual Correspondence via Graph-Cut based Energy Optimization

Computer graphics and computer vision were traditionally two distinct research fields focusing on opposite topics. Lately, they have been increasingly borrowing ideas and tools from each other. In this thesis, we investigate two problems in computer vision and graphics that rely on the same tool, namely energy optimization with graph cuts. In the area of computer graphics, we address the problem of generating artificial classic mosaics, still and animated. The main purpose of artificial mosaics is to help a user to create digital art. First we reformulate our previous static mosaic work in a more principled global optimization framework. Then, relying on our still mosaic algorithm, we develop a method for producing animated mosaics directly from real video sequences, which is the first such method, we believe. Our mosaic animation style is uniquely expressive. Our method estimates the motion of the pixels in the video, renders the frames with mosaic effect based on both the colour and motion information from the input video. This algorithm relies extensively on our novel motion segmentation approach, which is a computer vision problem. To improve the quality of our animated mosaics, we need to improve the motion segmentation algorithm. Since motion and stereo problems have a similar setup, we start with the problem of finding visual correspondence for stereo, which has the advantage of having datasets with ground truth, useful for evaluation. Most previous methods for stereo correspondence do not provide any measure of reliability in their estimates. We aim to find the regions for which correspondence can be determined reliably. Our main idea is to find corresponding regions that have a sufficiently strong texture cue on the boundary, since texture is a reliable cue for matching. Unlike the previous work, we allow the disparity range within each such region to vary smoothly, instead of being constant. This produces blob-like semi-dense visual features for which we have a high confidence in their estimated ranges of disparities

Wholetoning: Synthesizing Abstract Black-and-White Illustrations

Black-and-white imagery is a popular and interesting depiction technique in the visual arts, in which varying tints and shades of a single colour are used. Within the realm of black-and-white images, there is a set of black-and-white illustrations that only depict salient features by ignoring details, and reduce colour to pure black and white, with no intermediate tones. These illustrations hold tremendous potential to enrich decoration, human communication and entertainment. Producing abstract black-and-white illustrations by hand relies on a time consuming and difficult process that requires both artistic talent and technical expertise. Previous work has not explored this style of illustration in much depth, and simple approaches such as thresholding are insufficient for stylization and artistic control. I use the word wholetoning to refer to illustrations that feature a high degree of shape and tone abstraction. In this thesis, I explore computer algorithms for generating wholetoned illustrations. First, I offer a general-purpose framework, “artistic thresholding”, to control the generation of wholetoned illustrations in an intuitive way. The basic artistic thresholding algorithm is an optimization framework based on simulated annealing to get the final bi-level result. I design an extensible objective function from our observations of a lot of wholetoned images. The objective function is a weighted sum over terms that encode features common to wholetoned illustrations. Based on the framework, I then explore two specific wholetoned styles: papercutting and representational calligraphy. I define a paper-cut design as a wholetoned image with connectivity constraints that ensure that it can be cut out from only one piece of paper. My computer generated papercutting technique can convert an original wholetoned image into a paper-cut design. It can also synthesize stylized and geometric patterns often found in traditional designs. Representational calligraphy is defined as a wholetoned image with the constraint that all depiction elements must be letters. The procedure of generating representational calligraphy designs is formalized as a “calligraphic packing” problem. I provide a semi-automatic technique that can warp a sequence of letters to fit a shape while preserving their readability