PROPERTIES

Advantages

Disadvantages To talk in general about the properties of a pyramid data structure is difficult, because the approaches are very different, so also their properties. So these properties are special or often fulfilled. A common advantage is the speedup, this is the main reason why pyramids are used. Progressive refinement which is related to a speedup, but it is associated with a lower quality and can be easy realized because of the multiresolution representation in the pyramid. A big advantage is the view-independence, so you can use the same pyramid for an animation of the data set, without changing the pyramid, because the construction is a very expensive process. This is only valid if in the pyramid stored colors are not view-dependent, so you should only use view-independent shading models for computing the colors. The storage of colors and opacities in the pyramid are also a problem, because if the transfer-function changes, the pyramid has to be reconstructed, so for the sake of performance the transfer-function should not often change. It is also possible to compress the volume with a Laplacian pyramid, so you can use higher-resolutional volume data for visualization or you have decreasing hardware requirements, but this is only a special property and it is only a approximation of the original volume data stored. Normally you need additional memory for the pyramid, depending on the data stored in it. This should be normally no problem, e.g. for image pyramids, but the volume data needs much memory and restricts sometimes the data sets, so also the additional memory can be a restriction.
 

 

 Main Page