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Data Reconstruction

With the merged data file, it is very easy to reconstruct the original data.

The Graphics Data Reconstruction Algorithm is as follows.

  1. Read the smallest vertex and facet data from the merged file.
  2. Read the added vertex data, added facet data and deleted facet data from Vertex Addition List, Facet Addition List and Facet Deletion List respectively.
  3. Add the added vertices to the vertex list, delete the deleted facets from facet list and add the added facets to the facet list.
  4. Continue for all Vertex Addition Lists, Facet Addition Lists and Facet Deletion Lists.


Data Refinement

In order to refine graphics data, every level of graphics data must be kept and maintained according to moving or rotating objects. Every time objects are rotated, all vertices are translated using 4 by 4 matrix calculation. If whole vertices of every level are calculated, it takes more time than handling only the most detailed single data. Fortunately, with the above algorithm, there is no vertex deletion. This means that a vertex does not have to be re-calculated once it is calculated in the smaller level of data. Also, the total vertex amount of a merged file is the same as that of the most detailed single data. Then, it is possible to take almost the same time for translation of vertices compared with the most detailed single data.

On the other hand, while objects are rotated or expanded, only the least data are displayed. Therefore, it is much faster than displaying more detailed data. This is the basic idea of Progressive Refinement.