SEAMCR Version 1.2 (alpha test mode)

Author: William M. Chan

Date: July, 1999.

SEAMCR is a tool for extracting seam curves, and for decomposing and creating surface grids around surface discontinuities. Under mode 1, seam curves are automatically extracted from a collection of panel networks (PLOT3D surface format) that describe a geometry surface. Seam curves are curves at intersection between components, sharp creases, high curvature contours, and open boundaries. Small gaps between the panel networks are tolerated up to a user-specified absolute distance. After mode 1, the user may need to remove extranneous seam curves, and perform some splitting and/or concatenation to produce a clean set of seam curves. Under mode 2, SEAMCR takes the surface geometry and the clean set of seam curves, and automatically generates spider web surface grids at corners where 3 or more seam curves meet. It also automatically trims the seam curves away from the corners, redistributes points based on turning angle, and outputs a surgrd input file for the trimmed, redistributed seam curves.

Input Files

    (1) Multiple surface panel networks - plot3d format (modes 1,2)
    (2) Input parameters (modes 1,2)
    (3) Multiple seam curves - plot3d format (mode 2)

Output Files

    (1) Seam curves - plot3d multiple grid format (mode 1)
    (2) Spider web surface grids (mode 2)
    (3) Trimmed and redistributed seam curves (mode 2)
    (4) SURGRD input parameters file (mode 2)

Input Parameters

   IMODE = 1   Extract seam curves from surface geometry
           2   Create spider web surface grid, trim and redistribute seam
               curves and create surgrd input files from given surface
               geometry and set of seam curves

   ISYM  = 0   surface geometry not bounded by a symmetry plane
           1   surface geometry bounded by x constant symmetry plane
           2   surface geometry bounded by y constant symmetry plane
           3   surface geometry bounded by z constant symmetry plane

    ANG  : an edge of a surface panel is picked as a seam edge if
           the surface normal of the panel deviates from that of its
           neighboring surface panel by ANG degrees ( e.g., a flat
           plate would have ANG=0 )

 GAPTOL >0 absolute distance tolerated in gaps between surface
           panel networks
        <0 use default tolerance computed as fraction of diagonal of
           bounding box of all surface panels

   DSSC >0 global grid spacing for redistributed seam curves
        <0 use default

ETAMX,DETA,DFAR >0 marching distance, initial and end spacing for SURGRD
                <0 use defaults