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Apparatus for recognition of drawn shapes or view types for automatic drawing input in CAD system

  • US 4,933,865 A
  • Filed: 12/18/1987
  • Issued: 06/12/1990
  • Est. Priority Date: 12/20/1986
  • Status: Expired due to Fees
First Claim
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1. An apparatus for recognition of shapes in drawings for automatic drawing input in a CAD system, said apparatus comprising:

  • drawing reading means for producing image data including vectorized image data, based on reading of a drawing;

    character recognition means for recognizing types of shapes and characters including lengths, angles, and the like of contour lines based on the image data and producing character recognition data based on said recognition;

    line segment discrimination means for discriminating types of line segments in accordance with definitions assigned to each type of line segment based on the vectorized image data and producing line segment discrimination data based on said discrimination;

    centerline extraction means for extracting centerlines drawn in center positions of shapes from the line segments discriminated by said line segment discrimination means based on the image data, the character recognition data, and the line segment discrimination data and producing centerline extraction data based on said extraction;

    symmetry determination means, responsive to the image data and the centerline extraction data, for determining symmetry of a symmetrical shape based on intersections between the extracted centerlines and straight lines between endpoints of contour lines, distances between the endpoints of contour lines and the intersections, and angles between the centerlines and the straight lines between end points of contour lines and for producing symmetry data; and

    figure recognition means, responsive to the image data and the symmetry data, for recognizing at least one of an undetermined shape, a length of an undetermined line segment, and a position of the undetermined line segment undiscriminated by the line segment discrimination means, using at least one of the symmetical shape and the length and position of one of the line segments discriminated by said line segment discrimination means, and the character recognition data from said character recognition means.

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