Method and system for storage and fast retrieval of digital terrain model elevations for use in positioning systems
First Claim
1. A computer implemented method to store elevation data, the method comprising:
- compressing elevation data of a first portion of a Digital Elevation Model (DEM), in part, by normalizing elevation data within the first portion to generate first compressed elevation data, wherein normalizing elevation data includes subtracting a reference elevation from each elevation data value in the first portion;
storing the first compressed elevation data in a storage location of a storage media pointed to by a first index; and
storing the first index in the storage media.
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Accused Products
Abstract
Methods and apparatuses to generate and to access compressed and indexed elevations of Digital Elevation Models. In one aspect of the invention, a method to store elevation data includes: compressing elevation data of a first portion of a Digital Elevation Model (DEM) to generate first compressed elevation data; storing the first compressed elevation data in a storage location pointed to by a first index; and storing the first index. In another aspect of the invention, a method to retrieve elevation data includes: locating a first compressed portion of a Digital Elevation Model (DEM) using a first index; and decompressing the first compressed portion to retrieve first elevation data for at least one sample point in the Digital Elevation Model. The Digital Elevation Model has a plurality of compressed portions which includes the first compressed portion; and the first index points to a storage location where the first compressed portion is stored.
28 Citations
24 Claims
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1. A computer implemented method to store elevation data, the method comprising:
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compressing elevation data of a first portion of a Digital Elevation Model (DEM), in part, by normalizing elevation data within the first portion to generate first compressed elevation data, wherein normalizing elevation data includes subtracting a reference elevation from each elevation data value in the first portion; storing the first compressed elevation data in a storage location of a storage media pointed to by a first index; and storing the first index in the storage media. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A machine readable media containing executable computer program instructions which when executed by a digital processing system cause said system to perform a method to store elevation data, the method comprising:
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compressing elevation data of a first portion of a Digital Elevation Model (DEM) to generate first compressed elevation data; storing the first compressed elevation data in a storage location pointed to by a first index; and
storing the first index;dividing an area of the DEM into a plurality of tiles; dividing at least a first of the plurality of tiles into a plurality of subtiles; storing parameters required for determining whether or not a location is in one of the plurality of tiles; and storing parameters for determining whether or not the location is in one of the plurality of subtiles; wherein the first portion is one of a plurality of profiles in one of the plurality of tiles. - View Dependent Claims (10, 11, 12, 13)
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14. A digital processing system to store elevation data, the digital processing system comprising:
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means for compressing elevation data of a first portion of a Digital Elevation Model (DEM) to generate first compressed elevation data; means for storing the first compressed elevation data in a storage location pointed to by a first index; and means for storing the first index; means for dividing an area of the Digital Elevation Model into a plurality of tiles; means for dividing at least a first of the plurality of tiles into a plurality of subtiles; means for storing parameters required for determining whether or not a location is in one of the plurality of tiles; means for storing parameters for determining whether or not the location in one of the plurality of subtiles; a processor; and storage media configured to store processor executable instructions; wherein the first portion in one of a plurality of profiles in one of the plurality of tiles. - View Dependent Claims (15, 16, 17, 18)
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19. A machine readable media containing a data stream representing a Digital Elevation Model, the data stream being produced by a method comprising:
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compressing elevation data of a first portion of a Digital Elevation Model (DEM), including normalizing the elevation data to generate first compressed elevation data, wherein normalizing elevation data includes subtracting a reference elevation from each elevation data value in the first portion; storing the first compressed elevation data in a storage location pointed to by a first index as part of the data stream; and storing the first index as part of the data stream. - View Dependent Claims (20, 21, 22, 23)
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24. A computer implemented method to store elevation data, the method comprising:
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dividing a first portion of a Digital Elevation Model (DEM) into a plurality of tiles; for each of the plurality of tiles, compressing elevation data within the tile according to a first resolution; dividing at least one of the plurality of tiles into a plurality of subtiles; for each of the plurality of subtiles, compressing elevation data within the subtile according to a second resolution that has a higher resolution than the first resolution; storing in a storage media, parameters for determining whether a location is in one of the plurality of tiles; and storing in the storage media, parameters for determining whether the location is in one of the plurality of subtiles.
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Specification