Data compression and file segmentation in directmodel JT datastores
First Claim
Patent Images
1. An apparatus for creating lightweight data files, comprising:
- data storage in which lightweight computer aided design data may be selectively stored; and
a controller coupled to the data storage, the controller;
selectively extracting data elements from computer aided design data;
producing compressed data from the extracted data elements by employing lossy compression on three dimensional geometry data and lossless compression on remaining data extracted from the computer aided design data; and
writing the compressed data elements to one or more separate, uniquely identified data segments within the data storage and indexed by a table of contents.
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Abstract
The size of lightweight JT data files containing CAD data is reduced by employing lossy compression where acceptable for portions of the CAD data, such as 3D geometry data. Dictionary-based lossless compression for the remaining portions is augmented by exploiting common repeated structures for some portions, such as precise Brep data, and compressing separate but similar data, such as all metadata for a given part and all scene graph data, together as a single block. The compressed data is then written in separate, uniquely identified data segments indexed in a table of contents, allowing quick access to any data segment for streaming.
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Citations
19 Claims
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1. An apparatus for creating lightweight data files, comprising:
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data storage in which lightweight computer aided design data may be selectively stored; and a controller coupled to the data storage, the controller; selectively extracting data elements from computer aided design data; producing compressed data from the extracted data elements by employing lossy compression on three dimensional geometry data and lossless compression on remaining data extracted from the computer aided design data; and writing the compressed data elements to one or more separate, uniquely identified data segments within the data storage and indexed by a table of contents. - View Dependent Claims (2, 3, 4)
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5. A method of creating lightweight data files, comprising:
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selectively extracting data elements from computer aided design data; producing compressed data from the extracted data elements by employing lossy compression on three dimensional geometry data and lossless compression on remaining data extracted from the computer aided design data; and writing the compressed data elements to one or more separate, uniquely identified data segments indexed by a table of contents. - View Dependent Claims (6, 7, 8)
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9. An apparatus for accessing lightweight data files, comprising:
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data storage in which an internally divided lightweight computer aided design data file is stored; and a controller coupled to the data storage, the controller; identifying one or more separate data segments within the lightweight data file which contain computer aided design data elements to be accessed; for each data element to be accessed, determining a compression or decompression process associated with the respective data element according to a data type of each data element by selecting a lossy compression or decompression process for all three dimensional geometry data elements within the lightweight data file and a lossless compression or decompression process for each other data element within the lightweight data file; and compressing or decompressing contents of each of the identified data segments using the determined compression or decompression process to access the data elements. - View Dependent Claims (10, 11)
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12. A method of accessing lightweight data files, comprising;
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identifying one or more separate data segments within the lightweight data file which contain computer aided design data elements to be accessed; for each data element to be accessed, determining a compression or decompression process associated with the respective data element according to a data type of each data element; and compressing or decompressing contents of each of the identified data segments using the associated compression or decompression processes to access the desired data elements. - View Dependent Claims (13, 14)
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15. A non-transitory machine usable medium storing a lightweight computer aided design data structure, the lightweight computer aided design data structure comprising:
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one or more separate data segments each uniquely identified by an identifier, wherein each data segment contains at least part of one or more data elements extracted from computer aided design data and compressed, wherein data elements containing three dimensional geometry data are compressed using lossy compression and other data elements are compressed using lossless compression. - View Dependent Claims (16, 17, 18, 19)
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Specification