Simplification of objects rendered by polygonal approximations

COMPUTERS & GRAPHICS, no. 2 (1991): 175-184

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摘要

Current technology provides a means to obtain sampled data that digitally describes three-dimensional surfaces and objects. Three-dimensional digitizing cameras can be used to obtain sampled data that maps the surface of three-dimensional figures and models. Data obtained from such sources enable accurate renderings of the original surfac...更多

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简介
  • As the technologically oriented civilization becomes increasingly more complex and sophisticated, the cost of training operators and technicians becomes more costly and time consuming.
  • Recent work has focused on increasing the usefulness and effectiveness of the projects by incorporating real-world terrain data, including topography from digital survey databases, as well as reflectance and cultural feature information from photogrammetrically processed stereopair aerial photographs [Ref. 7]
  • These simulators, for example, allow one to pilot a ship on the waters of the Sea of Japan, or to drive a jeep across the terrain of Fort Hunter-Liggett, California.
  • In order to overcome these problems, a project was undertaken to provide the vehicles in these simulators the same degree of accuracy and detailing as that available from using digital topography information for the terrain models
重点内容
  • As our technologically oriented civilization becomes increasingly more complex and sophisticated, the cost of training operators and technicians becomes more costly and time consuming
  • The idea is to use one’s knowledge about the system and the problem in order to more quickly guide the program to the solution. Current work on this project has focused on the systematic generation approaches to the simplification of rendered objects
  • The initial results are very encouraging; sample data of a human bust consisting of 112,640 points was successfully reduced to 12,821 polygons using the extra vertex-greatest error variation of the adaptive subdivision method (g2e)
  • This drastic reduction in object complexity resulted in an order of magnitude increase in drawing speeds
  • Further investigation into improving the accuracy metrics, and into rules concerning how to subdivide a polygon should result in greater reductions
  • Methods of combining several sets of data from the camera for objects too large to digitize in one pass
方法
  • The basic adaptive subdivision method as presented by Schmitt et. al. is sketched in Figure 3.
  • Sketch 3a shows several data points produced by the sampling process and sketch 3b adds a trial polygon that approximates the surface represented by the sample points.
  • The distance between the surface and the data point is calculated, as shown in Figure 3c, and is compared to the user specified tolerance.
  • If any of the errors exceeds the tolerance value the polygon is divided into four smaller polygons, as shown in Figure 3d, and the process is repeated recursively
结果
  • This project was undertaken to investigate possible methods for creating realistic ships, trucks and other inhabitants of the real-time 3D visual simulators being developed at the Naval Postgraduate School.
结论
  • Current work on this project has focused on the systematic generation approaches to the simplification of rendered objects.
引用论文
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