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Chapter 3: Data structures and file formats

Chapter 3: Data structures and file formats

Introduction

Data structures recognized by gredit as inputs can be classified as follows:

  • Grids

  • Grid boundaries

  • Coastal outlines

  • Build points

    File contents for each identified data structure are now described. For each type of data structure, two major format options are or will be available: one ASCII, and one binary.

    Grids

    A data structure, representing the grid to edit. It's currently configured as a 2D finite element grid, formed by 3-node triangles.

    ASCII format

  • alphanumeric identifier

  • number of elements, number of nodes

  • node_number, x, y, depth | repeat for each node

  • element_number, number_of_nodes, node(1), node(2),..., node(number_of_nodes) | repeat for each element, in a counterclockwise orientation.

    Example of a grid in ASCII format: 

    This is a line of alpha
2 4   # number of elements and number of nodes
1 0.0 0.0 1.0  # node number, x, y, depth
2 1.0 0.0 9.0  # node number, x, y, depth
3 1.0 1.0 3.0  # node number, x, y, depth
4 0.0 1.0 2.0  # node number, x, y, depth
1 3 1 2 4      # element number, number of nodes, node list
2 3 2 3 4      # element number, number of nodes, node list
    Binary format

    The following applies to grids composed of triangles only.

  • 4 byte integer giving length of record ( = 4).
  • 4 byte integer magic number ( = 2).
  • 4 byte integer giving length of record ( = 4).
  • 4 byte integer giving length of record ( = 4).
  • 4 byte integer number of elements.
  • 4 byte integer giving length of record ( = 4).
  • 4 byte integer giving length of record ( = 4).
  • 4 byte integer number of nodes.
  • 4 byte integer giving length of record ( = 4).
  • 4 byte integer giving length of record (4 * number of nodes).
  • 4 byte float with the x-coordinate of node positions.
  • 4 byte integer giving length of record (4 * number of nodes).
  • 4 byte integer giving length of record (4 * number of nodes).
  • 4 byte float with the y-coordinate of node positions.
  • 4 byte integer giving length of record (4 * number of nodes).
  • 4 byte integer giving length of record (4 * number of nodes).
  • 4 byte float with the depth-coordinate of node positions.
  • 4 byte integer giving length of record (4 * number of nodes).
  • 4 byte integer giving length of record (4 * number of elements).
  • 4 byte integer vector with the first node of connectivity for all elements.
  • 4 byte integer giving length of record (4 * number of elements).
  • 4 byte integer giving length of record (4 * number of elements).
  • 4 byte integer vector with the second node of connectivity for all elements.
  • 4 byte integer giving length of record (4 * number of elements).
  • 4 byte integer giving length of record (4 * number of elements).
  • 4 byte integer vector with the third node of connectivity for all elements.
  • 4 byte integer giving length of record (4 * number of elements).

    Edit grid Boundary

    The edit grid boundary represents the outline of the reference finite element grid.

    ASCII (x,y) format

  • alphanumeric identifier

  • number of boundaries

    For each boundary:

  • number of points in this boundary, magic number

  • x y / repeat for each point in this boundary

    ASCII nodal format

  • alphanumeric identifier

  • number of boundaries

    For each boundary:

  • number of points in this boundary, magic number

  • node number / repeat for each point in this boundary

    Binary format is currently not available

    Coastal outline

    This is a mandatory data structure only when an automatic placement of build points on the coastal outline is required. It represents the contour of the reference domain limits.

    ASCII format

  • alphanumeric identifier

  • number of boundaries

    For each boundary:

  • number of points in this boundary, magic number

  • x y / repeat for each point in this boundary

    Binary format is currently not available

    Build points

    ASCII format

  • alphanumeric identifier

  • number of build points

  • n x y depth / repeat for each build point

    Last Modified: 09:39am , April 25, 1997
    Copyright © 1997 Center for Coastal and Land-Margin Research