Piecewise linear cost propagation for path searching
First Claim
20-1. The product of claim 34, wherein the at least one computer readable medium is selected from the set of a disk, tape or other magnetic, optical, or electronic storage medium and a network, wireline, wireless or other communications medium.
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Abstract
The problem of searching for a low cost path from a source location to a target location through a traversable region partitioned into a plurality of tiles is solved using source and target cost functions. Each tile in the traversable region is defined by boundary segments. The source cost function provides a cost for traversing from the source location to the boundary segment in question. The target cost function provides a cost for traversing from the boundary segment in question to the target location. The target cost function is estimated, and the source cost function is calculated. A path cost function is determined by adding the source and target cost functions. If the target location is a tile, then the target cost may be estimated using a convex hull of the target tile and the boundary segment in question. To facilitate the cost function calculations, multiple forms of cost function propagation between segments are disclosed.
63 Citations
42 Claims
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20-1. The product of claim 34,
wherein the at least one computer readable medium is selected from the set of a disk, tape or other magnetic, optical, or electronic storage medium and a network, wireline, wireless or other communications medium.
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21. A method of propagating cost from entry segment of a tile to an exit segment of the tile, the method comprising:
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determining the relative orientation of the entry and exit segments;
performing a first type of cost function propagation if the entry and exit boundary segments have a first relative orientation; and
performing a second type of cost function propagation if the entry and exit boundary segments have a second relative orientation. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. A method of calculating a cost of a path from a source to a tile exit boundary segment, the path crossing a boundary of the tile at a tile entry boundary segment, the method comprising:
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providing an entry source cost, the entry source cost providing a cost from the source to the entry boundary segment;
calculating an exit source cost, the exit source cost providing a cost from the source to the exit boundary segment, the exit source cost depending in part on the entry source cost, the exit source cost being calculated without explicitly determining a propagation cost across the tile from the entry boundary segment to the exit boundary segment.
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33. A computer program product encoded in computer readable media for propagating cost from an entry segment of a tile to an exit segment of the tile, the product comprising:
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first instructions, executable by an information processing system for determining the relative orientation of the entry and exit segments;
second instructions, executable by an information processing system for performing a first type of cost function propagation if the entry and exit boundary segments have a first relative orientation; and
third instructions, executable by an information processing system for performing a second type of cost function propagation if the entry and exit boundary segments have a second relative orientation. - View Dependent Claims (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 35, 36, 38)
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34. A computer program product encoded in at least one computer readable medium for processing information for finding a low cost path from a source to a target through a traversable region partitioned into a plurality of tiles, each tile being defined by a plurality of boundary segments, the computer program product comprising:
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a software module for estimating a target cost function providing the cost to the target from an exit boundary segment of a tile; and
a software module for calculating a source cost function from the exit boundary segment to the source; and
a software module for calculating a path cost function from the source cost and the target cost.
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39. A method comprising the step of providing an information processing system in which a processor and a plurality of software modules are configured for processing information for finding a low cost path from a source to a target through a traversable region partitioned into a plurality of tiles, each tile being defined by a plurality of boundary segments, wherein the plurality of software modules include a first software module for estimating a target cost function providing the cost to the target from an exit boundary segment of a tile, a second software module for calculating a source cost function from the exit boundary segment to the source;
- and a third software module for calculating a path cost function from the source cost and the target cost.
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40. A method of estimating a least cost of a path from any point on a piecewise linear curve to a tile outlined by a plurality of boundary segments, the method comprising:
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finding a convex hull of the piecewise linear curve and the boundary segments of the tile;
selecting a boundary segment of the tile not on the convex hull;
propagating a cost function from the piecewise linear curve to the selected boundary segment; and
repeating the selecting and the propagating at least until all boundary segments of the not on the convex hull have been selected. - View Dependent Claims (41, 42)
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Specification