Construction of elements for three-dimensional objects

• US 5,353,390 A
• Filed: 11/21/1991
• Issued: 10/04/1994
• Est. Priority Date: 11/21/1991
• Status: Expired due to Fees

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Harrington, Steven J.
• Primary Examiner(s): Bayerl, Raymond J.
• Application Number:
  US07/795,607
• Time in Patent Office: 1,048 Days
• Field of Search: 395/120, 395/119, 395/123, 395/127, 395/133, 364/512, 434/79, 434/211, 434/365
• US Class Current: 345/420
• CPC Class Codes: G06T 17/20 Finite element generation, e.g. wire-frame surface description, tesselation

Abstract

Elements of a three-dimensional object having a plurality of flat polygonal surfaces are constructed by providing a visual model of the object and constructing a graph from the visual model. The graph illustrates a plurality of nodes connected by lines. Each node represents one of the polygonal surfaces, and each line connecting the nodes corresponds to an edge of the visual model located between corresponding polygonal surfaces. One of the nodes is selected as a starting node, and the graph is traversed beginning at the starting node. The traversal continues by successively traveling from previously selected nodes to previously unselected nodes along the lines without selecting any node more than once. The elements are constructed by drawing a corresponding polygon for each node as the nodes are selected.

Claims

1. A method of constructing elements for a three-dimensional object having a plurality of flat polygonal surfaces, said method comprising:

providing a visual model of the object;

constructing a graph from the visual model, said graph comprising a plurality of nodes connected by lines, each node representing one of the polygonal surfaces and each line connecting the nodes corresponding to an edge of the visual model located between corresponding polygonal surfaces;

selecting one of said nodes and traversing the graph beginning at the selected node, said traversing comprising successively traveling from previously selected nodes to previously unselected nodes along said lines without processing any node more than once; and

creating elements of the three-dimensional object on a page by drawing a corresponding polygon for each node as the nodes are visited.

2. An apparatus for constructing elements for a three-dimensional object having a plurality of flat polygonal surfaces, said apparatus comprising:

visual model specifying means for specifying a visual model of the object;

processing means including;

constructing means for constructing a graph from the visual model, said graph comprising a plurality of nodes connected by lines, each node representing one of the polygonal surfaces and each line connecting the nodes corresponding to an edge of the visual model located between corresponding polygonal surfaces;

selecting means for selecting one of said nodes; and

traversing means for traversing the graph beginning at the node selected by said selecting means, said traversing means traversing the graph by successively traveling from previously selected nodes to previously unselected nodes along said lines without processing any node more than once; and

printing means for creating elements of the three-dimensional object on a page by drawing a corresponding polygon for each node as the nodes are visited.

3. A method of constructing elements for a three-dimensional object having a plurality of flat polygonal surfaces, said method comprising:

providing a visual model of the object;

constructing a graph from the visual model, said graph comprising a plurality of nodes connected by lines, each node representing one of the polygonal surfaces and each line connecting the nodes corresponding to an edge of the visual model located between corresponding polygonal surfaces;

selecting one of said nodes and traversing the graph beginning at the selected node, said traversing comprising successively traveling from previously selected nodes to previously unselected nodes along said lines without processing any node more than once; and

creating elements of the three-dimensional object on a page by drawing a corresponding polygon for each node as the nodes are visited to form a two-dimensional unfolded pattern.

4. The method according to claim 3, wherein said act of drawing a corresponding polygon comprises drawing said polygon such that each boundary of the drawn polygon corresponding to a line between nodes correlates to a corresponding edge of the three dimensional object.

5. The method according to claim 3, wherein said traversing includes choosing an order of nodes for traversal such that when the polygons are drawn, a shape does not result which is larger than the page.

6. The method according to claim 3, wherein said traversing includes choosing an order of nodes for traversal such that a selected node which corresponds to a polygon, contains a longest boundary to any adjacent polygon previously selected.

7. The method according to claim 3, wherein said selecting includes selecting a node which corresponds to a polygon having a longest boundary with the polygon of the currently selected node.

8. The method according to claim 3, wherein said traversing includes choosing an order of nodes for traversal such that when the polygons are drawn, an overlap of polygons will not result.

9. The method according to claim 3, wherein when an order of traversal of nodes results in one of the following conditions:

1) an overlap of polygons;

     2) a shape which is larger than a page; and

     3) remaining nodes not reachable from previously selected nodes, said method further comprises the steps of;

a) traversing adjacent nodes on the graph until reaching a node prior to satisfy, one of the conditions;

b) drawing the corresponding polygons for each traversed node on a first piece of paper;

c) removing each traversed node from the graph;

d) selecting a beginning node from remaining nodes in the graph;

e) traversing the remaining nodes until reaching a node prior to satisfying one of the conditions;

f) drawing corresponding polygons for each remaining node traversed on an additional piece of paper; and

g) repeating steps c) through f) until all of the nodes have been traversed and all polygons have been drawn.

10. The method according to claim 3, further comprising:

determining a layout of polygons on the page prior to printing of the page;

printing polygon edges which correspond to lines followed in the traversal in one print style; and

printing remaining polygon edges in a print style different from said one print style.

11. The method according to claim 3, further comprising:

determining a layout of polygons on the page prior to printing of the page; and

printing labels associated with graph lines on polygon edges which do not correspond to lines of the graph followed in its traversal, said labels indicating which pairs of said edges should be joined together when assembling the three-dimensional object.

12. An apparatus for constructing elements for a three-dimensional object having a plurality of flat polygonal surfaces, said apparatus comprising:

visual model specifying means for specifying a visual model of the object;

processing means including;

constructing means for constructing a graph from the visual model, said graph comprising a plurality of nodes connected by lines, each node representing one of the polygonal surfaces and each line connecting the nodes corresponding to an edge of the visual model located between corresponding polygonal surfaces;

selecting means for selecting one of said nodes; and

traversing means for traversing the graph beginning at the node selected by said selecting means, said traversing means traversing the graph by successively traveling from previously selected nodes to previously unselected nodes along said lines without processing any node more than once; and

printing means for creating elements of the three-dimensional object on a page by drawing a corresponding polygon for each node as the nodes are visited to form a two-dimensional unfolded pattern.

13. The apparatus according to claim 12, wherein said printing means draws said polygons such that each boundary of the drawn polygons corresponding to a line between nodes correlates to a corresponding edge of the three dimensional object.

14. The apparatus according to claim 12, wherein said traversing means chooses an order of nodes for traversal such that when the polygons are drawn, a shape does not result which is larger than the page.

15. The apparatus according to claim 12, wherein said traversing means chooses an order of nodes for traversal such that a selected node which corresponds to a polygon, contains a longest boundary to any adjacent polygon previously selected.

16. The apparatus according to claim 12, wherein said selecting means selects a node which corresponds to a polygon having a longest boundary with the polygon of the currently selected node.

17. The apparatus according to claim 12, wherein said traversing means choses an order of nodes for traversal such that when the polygons are drawn, an overlap of polygons will not result.

18. The apparatus according to claim 12, wherein when an order of traversal of nodes results in one of the following conditions:

1) an overlap of polygons;

     2) a shape which is larger than a page; and

     3) remaining nodes not reachable from previously selected nodes, then;

a) said traversing means traverses adjacent nodes on the graph until reaching a node prior to satisfying one of the conditions;

b) said printing means draws a corresponding polygon for each traversed node on a first piece of paper;

c) said processing means removes each traversed node from the graph;

d) said selecting means selects a beginning node from remaining nodes of the graph;

e) said traversing means traverses the remaining nodes until reaching a node prior to satisfying one of the conditions;

f) said printing means draws corresponding polygons for each remaining node traversed on an additional piece of paper; and

g) said selecting means, said traversing means and said printing means repeat c) through f) until all of the nodes have been traversed and all polygons have been drawn.

19. The apparatus according to claim 12, wherein said processing means includes determining means for determining a layout of polygons on the page prior to printing of the page by said printing means, said printing means printing polygon edges which correspond to lines followed in the traversal in one print style and said printing means printing remaining polygon edges in a print style different from said one print style.

20. The apparatus according to claim 12, wherein said processing means includes determining means for determining a layout of polygons on the page prior to printing of the page and said printing means prints labels associated with graph lines on the polygon edges which do not correspond to lines of the graph followed in its traversal, said printing means printing said labels to indicate which pairs of said edges should be joined together when assembling the three-dimensional object.