JP2614356B2 - Closed figure extraction method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a closed figure extraction method for extracting an arbitrary closed figure in drawing data.

2. Description of the Related Art In a system that handles drawing data such as a CAD (Computer Aided Design) system, a specific closed figure is specified in created drawing data or read drawing data, and information in the closed figure is specified. , Or performing a specific process such as hatching on the closed figure.

Conventionally, in such a process of extracting a closed figure,
Line segments in which end points are connected are sequentially searched, and a closed figure is recognized based on whether or not the search start point is reached.

[Problems to be Solved by the Invention] However, such a closed figure extraction method is based on the premise that the end points of the line segments constituting the closed figure are connected. For this reason, for example, as shown in FIG. 4, although the end points A to H are not connected to each other,
When the closed graphic S is generated by the intersection of L1 to L4, the closed graphic cannot be extracted. For this reason, conventionally, in order to recognize such a closed figure S, it is necessary to newly input the coordinates of the intersection of each line segment, and there is a problem that the operation becomes complicated.

The present invention has been made to solve such a problem, and even when a closed figure is generated by intersection of line segments, an arbitrary closed figure can be extracted without any complicated operation. It is an object of the present invention to provide a closed figure extraction method capable of performing a closed figure extraction.

[Means for Solving the Problems] A closed figure extraction method according to the present invention comprises a coordinate input unit for inputting a coordinate point designating the inside of a closed figure, and a plurality of line segments surrounding the coordinate point input by the unit. Detecting the closest tangent to the input coordinate point and intersecting the plurality of line segments surrounding the coordinate point while maintaining the same positional relationship of the coordinate point with the search direction on the closest tangent. And a closed figure extracting means for extracting a closed figure from the coordinates of the intersections of the line segments extracted by this means.

[Operation] In the present invention, when a coordinate point designating the inside of a closed figure is input, a contour segment extracting unit extracts a plurality of line segments surrounding the coordinate point, and further, the closed figure extracting unit extracts the line segment. A closed figure is extracted from the coordinates of the intersection of the line segments.

Therefore, according to the present invention, the end points do not need to be continuous as prerequisites for extracting a closed figure, and it is not necessary to input the coordinate values of the intersections again. A simple operation can extract a closed figure.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a functional block diagram showing a configuration of a closed figure extracting apparatus according to an embodiment of the present invention.

In FIG. 1, a coordinate input means 1 comprises a pointing device such as a mouse, a keyboard or a joystick, and is a means for designating one point inside a closed figure.
The contour line segment extraction means 2 removes unnecessary line segments for search from the line segments in the graphic data, detects the closest line segment of the input point, and detects the smallest line segment connected to the detected closest line segment. Search for the line segments that make up a single stroke. The closed figure extracting means 3 recognizes the closed figure from the coordinate values of the intersections of the contour lines extracted by the contour line extracting means, and extracts this.

Next, the operation of the thus-configured closed figure extracting apparatus according to the present embodiment will be described.

FIG. 2 is a flowchart showing the operation of the closed figure extracting apparatus.

When the operator designates a closed graphic extraction process using a means (not shown), first, the contour line extraction means 2 removes unnecessary line segments from the graphic data for search (S1).

For example, in FIG. 3 (a), since all the line segments L1 to L4 intersect with other line segments, such a line segment is a search target. For example, like the line segment LL, Since line segments that do not intersect with any line segment cannot form a closed figure, such line segments are removed as unnecessary line segments. Thus, the search time can be reduced by narrowing down the search targets.

Next, as shown in FIG. 3 (b), when the operator designates a point P in the closed figure S to be extracted using the coordinate input means 1 (S2), the contour line extracting means 2 sets the point P The closest nearest line segment is detected by comparing the vertical length dropped to each line segment from (S3).

Here, if the line segment AB is the closest tangent line, the outer line segment extraction means 2 first starts a search from the start point A to the end point B of the line segment AB, and the first detected intersection point X1 is set as the start point, and when the intersection X2 is detected next, the search for the line segment GH is started while maintaining the same positional relationship of the point P with respect to the search direction (S5). When such a search is executed and the point of intersection X1 is reached again, the process ends (S
Four).

Next, the closed figure output means 3 emits a closed figure based on the intersections X1 to X4 extracted by the above-described processing,
Necessary processes such as hatching and information extraction in a closed figure as shown in FIG.

As described above, according to the present embodiment, even for a closed figure whose end points are not continuous, it is possible to perform a closed figure recognition process by sequentially searching for the intersection, and troublesome inputting the coordinates of the intersection. There is an advantage that no complicated operation is required.

Note that the present invention is not limited to the above-described embodiment. That is, in the above-described embodiment, the outer line segment including the point P is searched while sequentially finding the intersections that intersect the nearest tangent line segment. It is also possible to obtain all the intersecting line segments, obtain their intersections, and extract the line segments constituting the closed figure and their intersections from the positional relationship between these line segments and the point P. Good.

[Effects of the Invention] As described above, according to the present invention, a closed graphic created by a plurality of outlines whose end points are not continuous is also provided.
The closed figure extraction process can be performed by an extremely simple operation such as specifying a point inside the closed figure without inputting the intersection coordinates.

INDUSTRIAL APPLICABILITY The present invention is extremely effective particularly in applications such as extracting a specific region partitioned by a grid in a map database or the like.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a closed figure extracting apparatus according to an embodiment of the present invention, FIG. 2 is a flowchart of an outline segment extracting process in the apparatus, and FIG. 3 is a schematic diagram for explaining the operation of the apparatus. FIG. 4 is a schematic view for explaining a conventional problem. 1 ... Coordinate input means, 2 ... Outline segment extraction means, 3 ...
Closed figure extraction means.

Claims (1)

(57) [Claims] 1. Coordinate input means for inputting a coordinate point designating the inside of a closed figure, and a closest tangent line segment to the input coordinate point among a plurality of line segments surrounding the coordinate point input by this means. Contour line extraction means for sequentially extracting intersections of a plurality of line segments surrounding the coordinate point while maintaining the same positional relationship of the coordinate point with the search direction on the nearest tangent line segment; A closed figure extracting means for extracting a closed figure from the coordinates of the intersection of the extracted line segments.