Métodos para Criação de Terrenos Baseados em Traços
Autoria de Terrenos; Modelagem baseada em traços
Although it is an already well-stablished area in computer graphics, many studies in synthesis and visualization of terrain are being done nowadays. These studies take advantage of the opportunities of exploring the aspects of sketch-based modeling, parallel processing on GPU's, the use of real topographic data, among others. In this paper, we present an analysis of the state of the art in the area. We aim to identify opportunities, challenges and trends in modeling and visualization of terrain. And we identify possible future works. The synthesis methods can be grouped into ontogenetic methods, which seek to build visually satisfactory models, and teleological methods, which seek to build geomorphologically coherent models. Throughout this paper, we will discuss the term 'geomorphologically coherent', relating these methods with the natural phenomena that influence the formation of Earth's topography. We will show a way to specify landforms using sketches of base and of silhouette and of guide lines. Most of the researches to creation of terrains uses, primarily, sketches of silhouette. However, we believe that we can approach this problem using other classes of curve, what will allow us to build realistic models of terrain using, yet, fewer traces. During the development of this work, we implemented a framework to synthesis and visualization of terrains. With this tool, we created some applications to test some concepts presented throughout this work. Besides of the specification process and synthesis of landforms, we also addressed some visual aspects such as representation of land with a mesh in multi-resolution, which was adapted according to the point of view, and topics related to texture.