منابع مشابه
Hybrid Quadtrees
Discrete and continuous representations of space di er in their topological properties. Completing a discrete representation of a partition to cell complexes helps to hide the di erences from the user by allowing to apply the same model for topological relations [23]. However, the additional elements in the completed representation | edges and nodes | are not required explicitly; they can be de...
متن کاملShape approximation using quadtrees
-The quadtree representation encodes a 2" by 2" binary image as a set of maximal blocks of l's or O's whose sizes and positions are powers of 2. With the aid of the quadtree, a hierarchy of approximations to the image can be defined. Several ways of doing this are described. The accuracy of these approximations is empirically evaluated by studying how fast estimates of the first few moments of ...
متن کاملConstructing Orientation Adaptive Quadtrees
A novel spatial data structure called the orientation adaptive quadtree (OAQ) is presented. The data structure takes advantage oflarge second-order moments of inertia of planar objects by aligning the quad tree axes with the object's principal axis of inertia. This provides a reduction in the number of leaf nodes necessary to store the quadtree compared to quadtrees aligned with the object coor...
متن کاملQuadtrees - Hierarchical Grids
Let P be a planar map. To be more concrete, let P be a partition of the unit square into triangles (i.e., a mesh). Since any simple polygon can be triangulated, P can represent any planar map, and its partition of the unit square into different regions, with different properties. For the sake of simplicity, assume that every vertex in P shares at most, say, nine triangles. Let us assume that we...
متن کاملVariable Spatial Resolution: Quadtrees
The concept of variable spatial resolution implies varying sized units at a given resolution level. The choise of the shape is a special matter. The square is particular handy if the process of creating the blocks of varying size is one of the decomposing space from a general level to more detail. For example, a polygon can be successively approximated by sets of blocks at different levels: If ...
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ژورنال
عنوان ژورنال: The Computer Journal
سال: 1986
ISSN: 0010-4620,1460-2067
DOI: 10.1093/comjnl/29.5.472