J. Edward Swan II

Object-Order Rendering of Discrete Objects

J. Edward Swan II. Object-Order Rendering of Discrete Objects. Ph.D. Thesis, Department of Computer and Information Science, The Ohio State University, 1997. Defended May 12, 1997.

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Abstract

This dissertation gives accurate and efficient methods for the object-order rendering of discrete objects. Discrete objects are typically represented with a volume raster and rendered with a volume rendering algorithm. However, current object-order volume rendering algorithms suffer from several problems. First, they require that the volume raster be traversed in a strict visibility order, but existing visibility ordering methods do not always correctly order perspective projections of volume rasters. Second, both perspective and orthographic renderings of volume rasters can contain aliasing artifacts, but current object-order techniques have no method for addressing these artifacts. Third, computer-generated animations suffer from temporal aliasing artifacts, which can be addressed by adding motion blur. But currently the only motion-blur method for object-order techniques is super-sampling, which is very expensive. This dissertation presents three new techniques for the object-order rendering of discrete objects which address these shortcomings. First, it gives and proves the correctness of a new method for traversing a rectilinear volume raster in an order that guarantees correct visibility under a perspective projection. Second, it introduces an innovative technique for eliminating the aliasing artifacts that occur when rendering a discrete object. Third, it gives a new technique for adding motion blur to renderings of discrete objects which is much more efficient than super-sampling. It uses the common object-order volume rendering method of splatting as a testbed for realizing these new techniques. This dissertation gives examples of the new techniques applied to volume rendering confocal data, texture-mapping discrete polygons, and rendering terrain datasets. In particular, the terrain representation is innovative compared to traditional object-order methods, which typically represent the terrain with triangular surface patches. A discrete representation has many advantages over more traditional surface-based representations for many objects besides just terrains. These advantages make it likely that discrete representations will be increasingly used in the coming years. To date, however, the algorithms available for rendering discrete objects have been less mature than those for rendering surface-based objects. The techniques presented in this dissertation promise to help close this gap, and thus make the advantages of a discrete representation more widely available.

BibTeX

@PhDThesis{DISS97-oor, 
  author =      {J. Edward {Swan~II}}, 
  title =       {Object-Order Rendering of Discrete Objects}, 
  school =      {Department of Computer and Information Science, The Ohio State University}, 
  note =        {Defended May 12, 1997.}, 
  month =       {May}, 
  year =        1997, 
  abstract =    { 
This dissertation gives accurate and efficient methods for the 
object-order rendering of discrete objects.  Discrete objects are 
typically represented with a volume raster and rendered with a volume 
rendering algorithm.  However, current object-order volume rendering 
algorithms suffer from several problems.  First, they require that the 
volume raster be traversed in a strict visibility order, but existing 
visibility ordering methods do not always correctly order perspective 
projections of volume rasters.  Second, both perspective and 
orthographic renderings of volume rasters can contain aliasing 
artifacts, but current object-order techniques have no method for 
addressing these artifacts.  Third, computer-generated animations 
suffer from temporal aliasing artifacts, which can be addressed by 
adding motion blur.  But currently the only motion-blur method for 
object-order techniques is super-sampling, which is very expensive. 
This dissertation presents three new techniques for the object-order 
rendering of discrete objects which address these shortcomings.  First, 
it gives and proves the correctness of a new method for traversing a 
rectilinear volume raster in an order that guarantees correct 
visibility under a perspective projection.  Second, it introduces an 
innovative technique for eliminating the aliasing artifacts that occur 
when rendering a discrete object.  Third, it gives a new technique for 
adding motion blur to renderings of discrete objects which is much more 
efficient than super-sampling.  It uses the common object-order volume 
rendering method of <em>splatting</em> as a testbed for realizing these new 
techniques. 
This dissertation gives examples of the new techniques applied to 
volume rendering confocal data, texture-mapping discrete polygons, and 
rendering terrain datasets.  In particular, the terrain representation 
is innovative compared to traditional object-order methods, which 
typically represent the terrain with triangular surface patches. 
A discrete representation has many advantages over more traditional 
surface-based representations for many objects besides just terrains. 
These advantages make it likely that discrete representations will be 
increasingly used in the coming years.  To date, however, the 
algorithms available for rendering discrete objects have been less 
mature than those for rendering surface-based objects.  The techniques 
presented in this dissertation promise to help close this gap, and thus 
make the advantages of a discrete representation more widely available. 
}, 
}