ISSN:1049-8907    

DOI:10.1002/vis.4340060402

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper describes a dynamic model to simulate expressive wrinkles in 3D facial animation and skin ageing. A skin surface is defined that can slide over an underlying layer, which constrains the surface by a spring force that simulates the connective fat tissue between them. Muscle masks are constructed to characterize the muscular contractions that provide the facial movement. Skin deformation is simulated through an elastic process assembled with visco and plastic units. By adjusting parameters for this physically based model, distinctive wrinkles for different faces can be generated.

ISSN:1049-8907    

DOI:10.1002/vis.4340060403

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractDirect volume rendering techniques present a huge potential for displaying a great amount of information in 3D data sets within one image. However, generating such an image is extremely expensive, and rendering for high quality pictures is far from interactive. Traditional volume rendering approaches are based on a cell‐by‐cell model. They consider cells as the smallest manipulation object. The time complexity of the volume rendering is determined by the number of cells, and the image quality, to some extent, is affected by the cell tessellation of volumes. Many scientists and technicians rarely venture to research the exploitation of coherence of function distribution over scalar fields through partition of data volumes. This paper proposes a new volume rendering approach: subvolume projection. It not only exploits the spatial coherence of cells but employs fully the spatial coherence of function distribution to partition a volume into a number of subvolumes, so that the function varies slowly over each subvolume. Each newly generated subvolume can be considered as containing a single material and treated as the smallest unit instead of cells in the processing. Based on the subdivision of the volume, this paper discusses the calculation of intensity contributed by the subvolumes in detail. Theoretical analysis and a variety of experimental results show that the new approach improves image quality and reduces rendering time period. (Usually the new algorithm is three to four times faster than the traditional volume rendering algorith

ISSN:1049-8907    

DOI:10.1002/vis.4340060404

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractFractal geometry provides an outstanding mathematical tool for simulating natural phenomena. However, the recursive process of stochastic modelling in generating random fractals puts forward difficult problems in the rendering. At present, only some special ray tracing methods have been provided to render fractals, mainly producing specular illumination. This paper proposes a radiosity solution for rendering random fractals, in which diffuse interreflection can be calculated in the process of stochastic modelling. By this solution, the recursive process of fractal generation is naturally incorporated into the progressive refinement procedure of the radiosity solution. Particularly, it becomes possible for fractal surfaces to participate in the energy shooting process of the radiosity solution.The key problem in the proposed approach is in calculating the radiosity redistribution for fractal subdivision. An algorithm for solving the problem has been proposed and implemented. Test examples show that the method is quite efficient. The technique may improve the visual realism of the radiosity image and promote the practical value of the radiosity solution.

ISSN:1049-8907    

DOI:10.1002/vis.4340060405

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper describes methods that can be used for modelling radiative properties of light sources and materials, in a radiosity computation algorithm. These methods have been designed in order to improve the photo‐realistic rendering of complex architectural scenes as well as to allow illumination engineering applications. They are based on the accurate modelling of the spatial and spectral emittance distributions of the light sources, and the surface reflectance/transmittance distributions from measurement, and allow the exact colorimetric properties of the light sources and the surfaces to be calculated. A method for changing radiosity inputs during the radiosity process, without recalculating the solution entirely is also proposed. This allows modifications in design or dynamic lighting effects to be simulated more interactivel

ISSN:1049-8907    

DOI:10.1002/vis.4340060406

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

ISSN:1049-8907    

DOI:10.1002/vis.4340060407

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

ISSN:1049-8907    

DOI:10.1002/vis.4340060401

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY