초록 ▼

A data compression/decompression method incorporating aliasing error reduction. An array of terrain data is first scanned for a set of modes and indexes are assigned to those modes. These modes are used as precision points for compression and decompression. A compressed index database is created usi

A data compression/decompression method incorporating aliasing error reduction. An array of terrain data is first scanned for a set of modes and indexes are assigned to those modes. These modes are used as precision points for compression and decompression. A compressed index database is created using the associated modes for the original terrain data. If the number of modes exceed a predetermined number the number of modes is collapsed using an aliasing technique. The alias error is tracked during the compression cycle. Total aliasing error is kept to a local minimum. The compressed data is decompressed by decoding and accessing the index database for the elevation alias. Further compression is accomplished using a lossless coding technique.

대표청구항 ▼

A source database compression method wherein the source database comprises a first plurality of data points each with a data value, the database compression method comprising the steps of: (a) assigning a unique index value to each unique value of the source database; (b) generating an index databas

A source database compression method wherein the source database comprises a first plurality of data points each with a data value, the database compression method comprising the steps of: (a) assigning a unique index value to each unique value of the source database; (b) generating an index database comprising a second plurality of data corresponding to the first plurality of data points, wherein each second plurality of data points has a value equal to the index value associated with the corresponding data value; (c) generating a mode database for each unique value of the source database wherein the mode database contains the frequency of occurrence of each unique value of the source database; (d) initializing an accumulated error value to zero; (e) locating a least frequent element of the mode database with the smallest frequency of occurrence; (f) locating the closest element of the mode database to the least frequency element that minimizes the accumulated error wherein the minimum accumulated error is determined by adding the accumulated error value to the difference between the value of the least frequent element minus the value of the closest element; (g) adding the frequency value of the least frequent element to the frequency value of the closest element; (h) eliminating the least frequent element from the mode database; and (i) repeating steps (c) through (g) until the mode database contains no more than a predetermined number off elements.