JP3894420B2 - 3D model generation method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for generating a three-dimensional model from raster data. The present invention particularly relates to a method and an apparatus for easily generating a three-dimensional model in the case of a three-dimensional shape including a complicated shape.
[0002]
[Prior art]
A technique for reproducing a three-dimensional shape from CAD data (hereinafter also referred to as “vector data”), which is vectorized drawing data, has been established mainly in the field of architecture and parts design. On the other hand, conversion of a drawing described by raster data (hereinafter also referred to as “raster drawing”) to vector data is performed by picking up the position of a point on the drawing with a digitizer. In recent years, there has been an increase in the number of structures that use curved surfaces from the viewpoint of design, mainly in the field of architecture. In order to make such structures into a three-dimensional model, the number of input points by the digitizer has increased, and the labor of the operator Perseverance is needed.
[0003]
[Problems to be solved by the invention]
Research on a method of modeling a structure including a complicated curved surface from a plurality of drawings in a three-dimensional manner has been made in many fields. However, as described above, since these are based on the use of vector data, for example, when a building having a free-form roof shape is targeted, the above-described work amount cannot be reduced.
[0004]
In the construction field, material accumulation and work schedule planning are performed based on drawings. In order to perform this work quickly and accurately, a demand for confirming an actual three-dimensional shape is increasing particularly on the site side. Especially in large buildings, if the curved surface is simply approximated by polygons, the absolute amount of materials is large, resulting in a large amount of money, which hinders the smooth execution of work for those who are actually responsible for construction. It has come.
[0005]
There are similar problems in other fields. For example, in the CG field, in order to generate a three-dimensional model from a drawing expressed in two dimensions, the drawing data is acquired by a digitizer. There is a big burden.
[0006]
The present invention has been made in view of such circumstances, and an object thereof is to provide a technique for easily generating a three-dimensional model of a three-dimensional shape described two-dimensionally by raster data from a plurality of drawings.
[0007]
In Japanese Patent Laid-Open No. 6-243202, “autostereoscopic generation system from three views” is mentioned, but the object of the present invention is different from that of the present invention in that vector data is used. Similarly, in Japanese Patent Application Laid-Open No. 11-134509, “drawing recognition method and architectural drawing recognition processing method” is mentioned. However, the present invention is also different from the present invention in that only vector data is handled.
[0008]
[Means for Solving the Problems]
One embodiment of the present invention relates to a three-dimensional model generation apparatus. This apparatus includes an image input unit that inputs a drawing in which a three-dimensional shape is represented two-dimensionally from different angles as raster data, a geometric adjustment unit that aligns a plurality of input drawings from a geometric point of view, A feature point extraction unit that extracts feature points in any of the drawings, and a corresponding point detection unit that detects corresponding points of the extracted feature points or candidates thereof on other matched drawings.
[0009]
The image input unit may input raster data of a drawing optically acquired by a scanner, for example, or may input raster data from a file such as a bitmap. Here, “raster data” refers to numerical data with respect to a sequence of dots formed in a grid pattern on an image. However, in this specification, the definition is not limited to this, and data in a format other than “vector data” is widely used. Including data. The “feature point” has only a feature in the sense that it can be easily extracted, and does not necessarily depend on a subjective factor. “Corresponding point or its candidate” may be a candidate because the corresponding point may not be identified uniquely or due to an external factor such as an error depending on the relationship of the drawing or the position of the feature point. To do. In this case, the apparatus may include a “corresponding point determination unit” that accepts selection of corresponding points or manual input from an operator. The “corresponding point or its candidate” is hereinafter simply referred to as “corresponding point”.
[0010]
According to this apparatus, a three-dimensional model of a three-dimensional shape is realized based on a raster drawing, for example, a bitmap format drawing formed by taking a drawing printed on paper. Therefore, even in a site where only a paper drawing exists at hand, for example, if a scanner is provided, the three-dimensional shape can be confirmed relatively easily.
[0011]
The apparatus may further include a coordinate calculation unit that calculates the three-dimensional coordinates of the feature point using the positional relationship between the feature point and the corresponding point as a clue.
[0012]
In addition, a data output unit that outputs data including the calculated three-dimensional coordinates in a standard file format, for example, a file format used in other general CAD systems may be included.
[0013]
In addition, a display processing unit that performs processing for plotting and displaying feature points in a three-dimensional manner based on the calculated three-dimensional coordinates, and a curved surface generation unit that generates a free-form surface indicating the outer shape of a three-dimensional shape may be included. Good.
[0014]
The geometric adjustment unit only needs to perform arbitrary processing such as correction of the inclination of the drawing, origin correction, and scale adjustment. The essence is to improve the detection accuracy by the corresponding point detection unit or to easily determine the corresponding point by the operator. Is to make it.
[0015]
The feature point extraction unit may automatically detect at least one of an intersection, a corner point, and an end point by employing an image processing method. That is, a technique that assumes an error of image processing is introduced in a technical field that originally handles absolute data as vector data, such as CAD. Further, the “image processing method” referred to here may be any method as long as the feature point can be detected, such as spatial filter processing.
[0016]
Another aspect of the present invention also relates to a three-dimensional model generation apparatus. This apparatus includes an image input unit that inputs a three-view drawing representing a design object, and a geometric adjustment unit that aligns the plurality of input drawings by processing including at least one of tilt correction, origin alignment, and scale adjustment. And a feature point extraction unit that extracts a feature point using an image processing method in any of the plurality of drawings, and a corresponding point of the extracted feature point or a candidate for the feature point on another drawing. And a corresponding point detection unit that detects based on the consistency realized by the adjustment unit. “Based on the consistency realized by the geometric adjustment unit” means that, for example, the scales of the three views are matched and the origin positions are matched. For example, if the plan view is drawn on the xy plane and the front view is drawn on the xz plane, the feature point taken in the former is equal to the x coordinate of the corresponding point in the latter, and the corresponding point detection process is easy. become.
[0017]
Yet another embodiment of the present invention relates to a three-dimensional model generation method. The method includes a step of aligning a plurality of drawings representing a three-dimensional shape in two-dimensional raster data from different angles from a geometric point of view, a step of defining feature points in any of the plurality of drawings, and a definition Detecting corresponding points of candidate feature points or candidates thereof on other matched drawings.
[0018]
It should be noted that any combination of the above components and the expression of the present invention expressed as a method, system, computer program, recording medium, etc. are also effective as an aspect of the present invention.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, as an embodiment of the present invention, a three-dimensional model generation process from a three-view drawing in architecture will be described.
[0020]
FIG. 1 shows a configuration of a three-dimensional model generation apparatus 10 according to the embodiment. This apparatus 10 includes an image input unit 16 that acquires raster data of three views from a scanner 12 and an external storage device 14, a geometric adjustment unit 18 that geometrically adjusts an input image, and an intersection from the adjusted plan view. A feature point extraction unit 26 that extracts feature points such as end points and corner points, a corresponding point detection unit 28 that detects corresponding points in the front view and side view of the extracted feature points, and detected corresponding points A coordinate calculation unit 52 that calculates the three-dimensional coordinates of the feature points based on the three-dimensional model, a three-dimensional model generation unit 54 that generates a three-dimensional model based on the calculated coordinates, and a display that displays the generated three-dimensional model The controller 30 includes a data output unit 32 that outputs the calculated three-dimensional coordinate data of the feature points to the external storage device 14, and a communication unit 34 that transmits the data to the network 44.
[0021]
The geometric adjustment unit 18 includes an inclination correction unit 20, an origin correction unit 22, and a scale adjustment unit 24.
[0022]
The inclination correction unit 20 first obtains a cumulative density histogram in the horizontal or vertical direction of the drawing. Rotate the figure little by little, for example, 0.1 degree by a predetermined angle range, that is, a range where the inclination of the drawing is assumed, for example, -5 ° to + 5 °, and automatically set the angle at which the peak of the cumulative density becomes maximum Ask. In architectural drawings, dimension lines are often drawn in the horizontal and vertical directions, and each element in the drawing often has a boundary surface in the horizontal and vertical directions. Accordingly, when the horizontal or vertical cumulative density histogram is taken, the angle at which the peak value of the histogram is maximum is estimated as the correct posture, and the drawing is corrected to this angle. This process is performed on a plan view, a front view, and a side view. FIG. 2 shows a flat screen after inclination correction and FIG. 3 shows a corrected horizontal density histogram after correction. It is shown that the peak value of the histogram is larger after correction.
[0023]
The processing of the origin correction unit 22 will be described with reference to FIGS. 4 (a) and 4 (b). The origin correction unit 22 prompts the operator to surround the figure 60 in the drawing of FIG. Subsequently, the origin correction unit 22 automatically corrects the origin of the drawing so that the lower left vertex 64 of the rectangle 62 coincides with the origin, and the drawing of FIG. 4B is obtained. However, the process of providing a circumscribed rectangle with the rectangle 62 may be automated by the origin correction unit 22.
[0024]
The scale adjustment unit 24 prompts the operator to select any two points in the drawing and input the distances. As these two points, if one having dimensions already entered in the drawing is selected, the operator only has to read and input the numerical value, so usually two such points are selected.
[0025]
The corresponding point detection unit 28 calculates and displays the corresponding points in the front view and the side view of the feature points for the plurality of feature points extracted by the feature point extraction unit 26. When the feature point or the corresponding point needs to be corrected, the corresponding point determination unit 50 accepts correction by the operator manually. This correction is done by dragging an arbitrary point with the mouse and moving it to the presumed correct position. The “correction” referred to here includes deletion of feature points.
[0026]
The coordinate calculation unit 52 specifies the x, y, and z coordinates in the three-view drawing of the feature point from the positional relationship between the feature point and the corresponding point, and the coordinate is based on the scale determined by the scale adjustment unit 24 described above. To real 3D coordinates.
[0027]
The three-dimensional model generation unit 54 calculates a free-form surface using a B-spline function based on the three-dimensional coordinates of the feature points, and generates a three-dimensional model. Here, the function used for calculating the free-form surface is not limited to the “B-spline function”, and any function can be used as long as it can calculate the free-form surface.
[0028]
The display control unit 30 displays the 3D model generated by the 3D model generation unit 54. Further, the three-dimensional coordinates of the feature points calculated by the coordinate calculation unit 52 may be displayed in a three-dimensional plot.
[0029]
FIG. 5 shows an example of a three-dimensional model generated by the three-dimensional model generation apparatus 10 based on a three-view drawing captured from the scanner. The upper left is a plan view, the lower left is a front view, and the lower right is a side view, in which feature points and corresponding points are displayed. In addition, feature points are three-dimensionally plotted in the upper right.
[0030]
FIG. 6 shows a three-dimensional model of another building generated based on a three-sided view (not shown), which is displayed by a wire frame having a different expression form from FIG. The effect of this embodiment can be seen.
[0031]
FIG. 7 is a flowchart showing a 3D model generation procedure by the 3D model generation apparatus 10 having the above configuration. The image input unit 16 acquires raster data of three views (S10). The geometric adjustment unit 18 performs geometric adjustment such as tilt correction, origin correction, and scale correction on the acquired drawing (S12). The feature point extraction unit 26 extracts feature points in the plan view by an image processing method (S14). The corresponding point detection unit 28 determines the corresponding points of the extracted feature points (S16), and the coordinate calculation unit 52 calculates the three-dimensional coordinates of the feature points (S18). The three-dimensional model generation unit 54 generates a three-dimensional model based on the three-dimensional coordinates of the feature points, and the display control unit 30 displays this (S20).
[0032]
The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.
[0033]
【The invention's effect】
According to the present invention, a three-dimensional model can be generated relatively easily from raster data.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a three-dimensional model generation apparatus according to an embodiment.
FIG. 2 is a photograph of a halftone image in which a cumulative density histogram is displayed on a display in a horizontal direction and a plan view before tilt correction.
FIG. 3 is a photograph of a halftone image in which a cumulative density histogram is displayed on a display in a horizontal view and a plan view after tilt correction.
4A and FIG. 4B are diagrams showing a side view before the origin correction and FIG. 4B a side view after the origin correction regarding the processing of the origin correction unit.
FIG. 5 is a photograph of a halftone image in which a plan view, a front view, a side view, and a diagram in which feature points are three-dimensionally plotted are displayed on a display after feature point association is completed.
FIG. 6 is a photograph of a halftone image that is displayed on a display example of a generated three-dimensional model using a wire frame.
FIG. 7 is a flowchart showing a 3D model generation procedure by the 3D model generation apparatus according to the embodiment;
[Explanation of symbols]
16 image input unit, 18 geometric adjustment unit, 20 tilt correction unit, 22 origin correction unit, 24 scale adjustment unit, 26 feature point extraction unit, 28 corresponding point detection unit, 30 display control unit, 32 data output unit, 50 corresponding point A determination unit, 54 a three-dimensional model generation unit.

Claims (11)

An image input unit for inputting, as raster data, a plurality of drawings each two-dimensionally representing a three-dimensional shape including a curved surface from a plurality of different angles;
A geometric adjustment unit for aligning a plurality of input drawings from a geometric point of view;
A feature point extraction unit for extracting feature points on the curved surface using an image processing technique in any of the plurality of drawings;
A corresponding point detection unit that detects corresponding points of the extracted feature points or candidates thereof on the other matched drawings;
A coordinate calculation unit that calculates the three-dimensional coordinates of the feature point using the positional relationship between the feature point and the corresponding point as a clue;
A three-dimensional model generation unit that calculates a free-form surface using a predetermined function based on the calculated three-dimensional coordinates of the feature points, and generates a three-dimensional model of the curved surface;
A three-dimensional model generation device comprising:   The apparatus according to claim 1, further comprising a data output unit that outputs data including the calculated three-dimensional coordinates in a standard file format.   The apparatus according to claim 1, further comprising a display processing unit that performs processing for plotting and displaying the feature points in a three-dimensional manner based on the calculated three-dimensional coordinates.   4. The apparatus according to claim 1, further comprising a curved surface generation unit configured to generate a free curved surface indicating the outer shape of the three-dimensional shape based on the calculated three-dimensional coordinates.   The apparatus according to claim 1, wherein the geometric adjustment unit performs processing including correction of a tilt of a drawing.   The apparatus according to claim 1, wherein the geometric adjustment unit performs processing including correction of an origin of a drawing.   The apparatus according to claim 1, wherein the geometric adjustment unit performs processing including scale adjustment of a drawing.   The apparatus according to claim 1, wherein the feature point extraction unit automatically detects at least one of an intersection, a corner point, and an end point by employing an image processing method. . An image input unit for inputting, as raster data, a three-view drawing representing a design object that is a three-dimensional shape including a curved surface ;
A geometric adjustment unit that aligns a plurality of input drawings by processing including at least one of tilt correction, origin alignment, and scale adjustment;
In any of the plurality of drawings, a feature point extraction unit that extracts feature points on the curved surface using an image processing technique;
A corresponding point detection unit that detects corresponding points of the extracted feature points or candidates thereof on the other drawings based on the consistency realized by the geometric adjustment unit;
A coordinate calculation unit that calculates the three-dimensional coordinates of the feature point using the positional relationship between the feature point and the corresponding point as a clue;
A three-dimensional model generation unit that calculates a free-form surface using a predetermined function based on the calculated three-dimensional coordinates of the feature points, and generates a three-dimensional model of the surface;
A three-dimensional model generation device comprising: Aligning a plurality of drawings representing a three-dimensional shape including a curved surface two-dimensionally from a plurality of different angles with raster data from a geometric point of view;
Defining a feature point on the curved surface using an image processing technique in any of the plurality of drawings;
Detecting corresponding points of the defined feature points or candidates thereof on other matched drawings;
Calculating the three-dimensional coordinates of the feature point using the positional relationship between the feature point and the corresponding point as a clue;
Calculating a free-form surface using a predetermined function based on the calculated three-dimensional coordinates of the feature points, and generating a three-dimensional model of the curved surface;
A three-dimensional model generation method comprising: Aligning a plurality of drawings representing a three-dimensional shape including a curved surface two-dimensionally with raster data from a plurality of different angles from a geometric point of view;
Defining a feature point on the curved surface using an image processing technique in any of the plurality of drawings;
Detecting corresponding points of the defined feature points or candidates thereof on other matched drawings;
Calculating the three-dimensional coordinates of the feature point using the positional relationship between the feature point and the corresponding point as a clue;
Calculating a free-form surface using a predetermined function based on the calculated three-dimensional coordinates of the feature points, and generating a three-dimensional model of the curved surface;
A computer program for causing a computer to execute.

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