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Apparatus for a video marine navigation plotter with electronic charting and methods for use therein

  • US 4,939,661 A
  • Filed: 09/09/1988
  • Issued: 07/03/1990
  • Est. Priority Date: 09/09/1988
  • Status: Expired due to Term
First Claim
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1. In a video navigation plotter for displaying linear geographic data occurring within a pre-defined geographic region, a method of storing the geographic data in said plotter and displaying the geographic data on a display, said method comprising the steps of:

  • representing said linear geographic data occurring in said region as a sequence of data calls with each data cell carrying a different cell number, wherein each successive cell encompasses a different successive pre-defined area existing within the region;

    storing each of said data cells as a memory cell within a memory, said memory cell containing a corresponding sequence of fields, said sequence defining a corresponding segment of said geographic data that occurs within the pre-defined area encompassed by said each data cell, wherein a first field in said sequence stores coordinates of a starting point of said segment and each successive field in said sequence stores a position offset value measured from a previous point in said segment to a next successive point in said segment, said segment point being defined by all offset values and said starting point that previously occur within said sequence;

    maintaining a table of individual memory cell numbers that defines an order in which said memory cells should be accessed in order to generate the linear geographic data;

    defining a numeric range of the memory cells, specified in said table, that collectively contain geographic data which forms a selected portion of the linear geographic data that is to be displayed on the display;

    successively accessing from the memory each of the memory cells that lies within said range of memory cells; and

    incrementally drawing, in response to each accessed memory cell, a pattern in a portion of a display screen, wherein said portion corresponds to the location of the data cell in the region and associated with said accessed memory cell and said pattern depicts the segment stored within said accessed memory cell and wherein said pattern is drawn as a series of connected line segments that begin at the starting point occurring within the sequence stored within the accessed memory cell, continue to a point specified by a first offset value occurring within the sequence stored within the accessed memory cell and extend to each corresponding point specified by each successive offset value occurring within the sequence stored within the accessed memory cell.

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