Method and apparatus for representing an area of a raster image by a centerline
First Claim
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1. A system, comprising:
- a processor; and
a storage device storing program instructions that when executed by the processor perform;
receiving a planar map which represents a raster image that contains a region, wherein a face in the planar map maps to the region in the raster image, and wherein the edges of the face map to the boundary of the region;
selecting as a subregion of the region a portion of the region whose width, as measured across the region from one boundary point to another boundary point, does not exceed a maximum-width threshold, wherein both the subregion and a portion of the region outside the subregion are currently represented by an outline comprising the edges of the face;
determining a centerline for the subregion, wherein the centerline coincides with at least a portion of a medial axis of the region; and
transforming the planar map so that the subregion is represented by the centerline, and so that the portion of the region outside the subregion is represented by an outline comprising a portion of the edges of the face.
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Abstract
One embodiment of the present invention provides a system that can represent an area of a raster image by a centerline. During operation, the system receives a planar map which represents a raster image that contains a region. Note that the region corresponds to a face in the planar map whose edges correspond to the boundaries of the region. Next, the system determines a centerline for a subregion within the region which is currently represented by an outline. The system then transforms the planar map so that the subregion is represented by the centerline.
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12 Claims
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1. A system, comprising:
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a processor; and a storage device storing program instructions that when executed by the processor perform; receiving a planar map which represents a raster image that contains a region, wherein a face in the planar map maps to the region in the raster image, and wherein the edges of the face map to the boundary of the region; selecting as a subregion of the region a portion of the region whose width, as measured across the region from one boundary point to another boundary point, does not exceed a maximum-width threshold, wherein both the subregion and a portion of the region outside the subregion are currently represented by an outline comprising the edges of the face; determining a centerline for the subregion, wherein the centerline coincides with at least a portion of a medial axis of the region; and transforming the planar map so that the subregion is represented by the centerline, and so that the portion of the region outside the subregion is represented by an outline comprising a portion of the edges of the face. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A system, comprising:
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a processor; and a storage device storing program instructions that when executed by the processor perform; receiving a raster image that contains a region; representing an area within the region by a centerline, which creates disjoint subregions of the region and creates corresponding emergent boundaries which are distinct from the centerline; identifying the emergent boundaries; identifying the disjoint subregions; associating each emergent boundary with one of the disjoint subregions; distinguishing each emergent boundary as either an inner boundary or an outer boundary; and pairing each inner boundary with its corresponding outer boundary. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification