JP2014109935A - Three-dimensional modeling method and three-dimensional modeling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently input a three-dimensional model.SOLUTION: A three-dimensional modeling system accepts input of face elements and generates a three-dimensional model as an area surrounded with a plurality of input face elements. It is preferable that the input of face elements is accepted by designation of points and directions. It is preferable that instructions to move or rotate already inputted face elements are accepted to generate again a three-dimensional model with the moved or rotated face elements. In generation of the three-dimensional model, it is preferable that a distance between each of pairs into which a plurality of face elements are coupled is obtained and face areas constituting the three-dimensional model are determined on the basis of lines of intersection between pairs of face elements in the ascending order of distance. In this case, it is preferable that an area including points designating face elements out of areas divided by a line of intersection is determined as a face area constituting the three-dimensional model. Further, it is preferable that the plurality of face elements are grouped and can be collectively moved and rotated.

Description

  The present invention relates to a three-dimensional modeling technique.

  In conventional three-dimensional modeling, vertices in space are used as basic elements. In general, a user places vertices in a space, connects the vertices with edges, and further defines a region closed by the edges as a surface to express a three-dimensional model. Since such a method directly reflects the internal representation of the computer, it is easy to implement and widely used.

  For buildings and the like, a three-dimensional model is expressed by a combination of large planes. When creating a model, an operation of translating or rotating the plane is required. However, it is difficult to move the apex in a coordinated manner while maintaining the flatness, which places a heavy burden on the user. For example, to pull out one face of a cube, it is necessary to move four vertices in parallel.

  In the techniques described in Non-Patent Document 1 and Patent Document 1, as shown in FIG. 23 (a), a surface is first created, and the surface is directly grasped and pulled out or pushed in, so that FIG. Modeling as shown is possible. However, even in this method, vertices are used for the internal representation, and if the existing surface is rotated, the flatness of the surrounding surfaces is lost, and it is impossible to place a new surface where there is nothing Have a problem. For example, in the three-dimensional model shown in FIG. 24A, when the surface P1 is rotated around the side S, the heights of the vertices V1 and V2 change, so that the surface as shown in FIG. The flatness of P2 is lost. Further, when changing the three-dimensional model shown in FIG. 25A to the three-dimensional model shown in FIG. 25B, a complicated operation is required.

US Pat. No. 6,628,279

"SketchUp", [online], Retrieved October 26, 2012, Trimble, <URL: http://www.sketchup.com/intl/en/index.html>

  An object of the present invention is to provide a three-dimensional modeling method and a three-dimensional modeling apparatus capable of efficiently inputting a three-dimensional model.

  In the present invention, a three-dimensional model is input using a surface as a basic element. More specifically, the three-dimensional modeling method according to the present invention includes an input step for receiving input of surface elements, and a modeling step for generating a three-dimensional model as a region surrounded by the plurality of input surface elements. .

  As described above, since the input of the surface element is received from the user and the region surrounded by the surface element is generated as a three-dimensional model, it is easy to create a three-dimensional model composed of a small number of planes. A building is mentioned as an example of the three-dimensional shape comprised of a small number of planes.

  In the present invention, it is preferable to further include a step of receiving an instruction to move or rotate the input surface element, and to regenerate the three-dimensional model based on the surface element after the movement or rotation.

  Since the 3D model generation based on the surface element is performed, the 3D model can be edited only by moving or rotating the surface element. That is, when the surface element is moved, it is not necessary for the user to translate each vertex so that the plurality of vertices maintain a plane. Further, when the surface element is rotated, it is not necessary to explicitly indicate the vertex position so that the surrounding planes are kept flat. That is, the user can edit the three-dimensional model by a simple operation.

  In the present invention, the method further includes a step of accepting a designation for grouping a plurality of surface elements. When an instruction for movement or rotation with respect to the plurality of grouped surface elements is accepted, the grouped surface elements are included in the grouped surface elements. It is preferable to apply the specified movement or rotation.

  As described above, by grouping a plurality of surface elements, an operation when the same movement or rotation is performed on the plurality of surface elements becomes easy.

  In the present invention, the modeling step of generating a three-dimensional model as a region surrounded by a plurality of surface elements includes a step of obtaining a distance between the surface elements for all combinations of the plurality of surface elements, and a pair of surface elements having a small distance. Preferably, the method includes, in order, a step of determining a surface region that constitutes the three-dimensional model based on the intersection line of the surface element pairs. In the present invention, the surface element can be specified by specifying a point and a direction. In this case, the distance between the surface elements may be obtained as a distance between points specifying the surface elements. In the step of determining the surface area, it is preferable that an area including an input point among areas divided by the intersection of the surface element pairs is determined as a surface area constituting the three-dimensional model.

  When there are a plurality of surface elements, it is not always easy to determine the shape of the polyhedron surrounded by these surface elements. According to the above method, it is possible to generate an appropriate three-dimensional model without requiring an operation other than the input of the surface element.

  In the present invention, when some of the input surface elements are grouped, the modeling step includes a step of determining a surface region constituting a three-dimensional model for the plurality of grouped surface elements; The surface area determined for a plurality of grouped surface elements is regarded as one element, and the surface area constituting the three-dimensional model is determined with other surface elements. preferable. In addition, when it has a hierarchical structure, such as when the grouped surface elements are further grouped, the above processing may be performed in order from the end element.

  In this way, it is possible to generate an appropriate three-dimensional model while maintaining the shapes of the grouped surface elements.

  The surface in the present invention may be a flat surface or a curved surface. When a plane is used, receiving a designation of a point and a direction (normal line) receives an input of the plane. In the case of using a curved surface, the input of the surface is accepted by accepting designation of a point, a direction, and a curvature.

  In the present invention, the method further includes a step of grouping and storing a plurality of combinations of surface elements in advance, and in the input step, a plurality of grouped surface elements stored in advance may be selected and arranged. preferable.

  In this way, a complicated shape composed of a plurality of surface elements can be easily input. Further, even when a plane is used as the surface element, the curved surface can be approximately expressed by a combination of a plurality of planes, so that the curved surface can be easily input.

  The present invention can be understood as a three-dimensional modeling method including at least a part of the above processing. It can also be understood as a program for executing the above method on a computer. Moreover, it can also be regarded as a three-dimensional modeling apparatus having means for executing the above processing.

  According to the present invention, it is possible to input a three-dimensional model efficiently.

The figure explaining the surface element which is a basic component of a three-dimensional modeling system. The figure explaining the modeling method in a three-dimensional modeling system. The figure explaining the modeling method in a three-dimensional modeling system. The figure which shows the apparatus structure of a three-dimensional modeling system. The figure which shows the external appearance of a three-dimensional modeling system. The figure which shows the structure of the input device used with a three-dimensional modeling system. The figure which shows the functional block of a three-dimensional modeling system. The figure which shows the example of the information which a surface element memory | storage part memorize | stores. The flowchart of the three-dimensional modeling method which a three-dimensional modeling system performs. The flowchart which shows the detail of the area | region determination process which determines the area | region of a three-dimensional shape from several surface element in a three-dimensional modeling method. The figure which demonstrates the area | region determination process of a three-dimensional shape concretely. The figure which demonstrates the area | region determination process of a three-dimensional shape concretely. The figure explaining the difference of the final three-dimensional shape by the difference in the center point arrangement | positioning of a surface element. The figure explaining grouping of several surface element. The figure explaining edit operation with respect to a group. The figure explaining edit operation with respect to a group. The figure explaining the difference of the final three-dimensional shape by the presence or absence of grouping. The figure explaining the difference of the final three-dimensional shape by the presence or absence of grouping. The figure which shows the structure when a scene contains a group. The figure explaining the area | region determination process between a group and a surface element. The figure explaining the area | region determination process between groups. The figure explaining the grouped primitive shape registered beforehand. The figure explaining the three-dimensional modeling method of a prior art. The figure explaining the problem in the three-dimensional modeling method of a prior art. The figure explaining the problem in the three-dimensional modeling method of a prior art.

  Hereinafter, a three-dimensional modeling system according to the present invention will be described with reference to the drawings.

(First embodiment)
<System overview>
The three-dimensional modeling system according to the present embodiment is a three-dimensional modeling system having plane elements as basic elements. That is, the main operations performed by the user are the arrangement of the surface elements expressed as points with orientation in the three-dimensional virtual space, and their movement / rotation. The three-dimensional modeling system calculates a region surrounded by a plurality of input surface elements and generates a three-dimensional model.

  In this system, the surface element is conceptually treated as a plane having an infinite extent, but in terms of implementation, it is trimmed so as to fit in a finite three-dimensional virtual space handled by the system. The surface element is specified by two positions and orientations. In the example of FIG. 1, two planes 101 and 102 are shown. The plane 101 is specified by a position (point) 101a and an orientation 101b. Similarly, the plane 102 is specified by a position (point) 102a and an orientation 102b. In the following, the position (point) input for designating the surface element is also expressed as the center or the center point of the surface element.

  In this system, it is also possible to edit the arranged surface elements. Specifically, the editing is an operation of moving the center point of the surface element or changing the direction of the surface element. That is, the movement (parallel movement) of the surface element is performed by moving the center point of the surface element, and the rotation about the center point of the surface element is performed by changing the direction of the surface element.

  Processing for creating a three-dimensional shape model from a plurality of surface elements will be described. As described above, the surface element is a plane that extends semi-infinitely. When a plurality of surface elements are arranged, intersection lines are obtained for all pairs of surface elements. The intersecting line of surface elements divides each surface element into two regions. Of the divided regions, a region including the center point of the surface element is defined as a surface region constituting the three-dimensional model, and a region not including the center point of the surface element is trimmed. Basically, a region constituting a three-dimensional model is determined by such processing, and a polyhedron composed of a plurality of surfaces is determined.

  When outputting the input three-dimensional shape as an image, an image is generated based on the vertex coordinates of the three-dimensional shape obtained as described above. However, in the system, the surface element is used as a basic element, and the center point and orientation are maintained. Therefore, when a surface element is newly added, the area surrounded by each surface element is recalculated to determine the three-dimensional shape.

  More specific description will be given with reference to FIG. FIG. 2A shows a state in which two planes 201 and 202 are arranged. The centers of the planes 201 and 202 are indicated by points 201a and 202a, respectively. The orientation of the plane is not shown. In this system, a horizontal plane representing the ground is set in advance, and trimming is performed on a portion below the ground among the surface elements input by the user. Description of surface elements corresponding to the ground is omitted in FIG. 2 and other drawings.

  As shown in FIG. 2B, the two planes 201 and 202 intersect at an intersection line 210, and each plane is divided. By leaving an area including the points 201a and 202a among the divided areas of the planes 201 and 202, an L-shaped shape as shown in FIG. 2B is obtained. Similarly, when a new plane 203 is added as shown in FIG. 2C, a U-shaped shape as shown in FIG. 2D is obtained. Furthermore, when a new plane 204 as shown in FIG. 2E is added, a triangular prism shape as shown in FIG. 2F is obtained. Thus, the polyhedron can be modeled only by an intuitive operation of arranging a plurality of planes.

  FIG. 2G shows a state where a plane 205 is further added to the model of FIG. Since trimming by the plane 205 is performed, a trapezoidal columnar shape is obtained as shown in FIG. In the method of inputting vertex coordinates, it is not easy to change the triangular prism shape shown in FIG. 2 (f) to the trapezoidal prism shape shown in FIG. 2 (h). However, according to this system, only one plane is added. Such a modification is possible.

  Furthermore, since this system allows operations such as movement and rotation with respect to the arranged surface elements, it is possible to edit the input three-dimensional shape while maintaining flatness. For example, among the surface elements constituting the three-dimensional shape shown in FIG. 3A, when the surface element P1 is rotated, the three-dimensional shape is changed as shown in FIG. Here, since the three-dimensional shape is determined as a region surrounded by the respective surface elements, even if the surface element P1 is rotated, the flatness of other surfaces is not lost. In the method of inputting vertex coordinates, when one surface is rotated, it is necessary to determine the vertex so as not to lose the planarity of the other surface. According to this system, the user considers maintaining the planarity. Without changing the shape of FIG. 3A, the shape of FIG. 3A can be changed to the shape of FIG.

<Configuration>
FIG. 4 is a diagram showing a device configuration of the three-dimensional modeling system 400 according to the present embodiment. The three-dimensional modeling system includes a CPU (central processing unit) 402, a main memory 404 such as a RAM, a storage unit 406, an input unit 408, and an output unit 410. The CPU 402 functions as a functional unit as shown in FIG. 7 by executing an operating system (OS) and an application program (three-dimensional modeling program) stored in the storage unit 406. The input unit 408 is an interface for transmitting an instruction from the user to the three-dimensional modeling system 400. As the input unit 408, a mouse, a keyboard, a touch screen, or the like can be used. A motion capture device may be used as the input unit 408 to facilitate three-dimensional input. The output unit 410 is an interface for presenting information from the three-dimensional modeling system 400 to the user. As the output unit 410, a display, a speaker, or the like can be used. It is also preferable to use a head mounted display (HMD) as the output unit 410. Here, an example in which the system is configured by one computer has been described, but the system may be configured by a plurality of computers connected to each other via a network.

  FIG. 5 is a diagram showing an overview of a three-dimensional modeling system 500 implemented using a motion capture device. In this example, as the input unit 408, a motion capture device configured by an input device 508 operated by a user, a plurality of cameras 506a to 506d, and motion capture software (executed by the computer 502) is employed. Although four cameras are shown here, the number of cameras may be arbitrary. The user operates the input device 508 to model a three-dimensional shape. The computer 502 performs a three-dimensional modeling process based on the input from the user and outputs the result to the display 504. Here, an example in which a flat panel display (FPD) is used as the output unit 410 is shown, but if a 3D image is displayed using a head-mounted display, the sense of immersion in the 3D virtual space can be enhanced. it can.

  FIG. 6 is a diagram showing details of the input device 508. As shown in FIG. 6A, the input device 508 includes a gripping part 601 and a flat part 602. The grip unit 601 is provided with buttons 603 a and 603 b, and an input from the user is transmitted to the computer 502. FIG. 6B is a diagram showing the flat portion 602 from the front. In this example, the flat portion 602 has a disk shape, and four markers 604a to 604d are attached to the surface thereof. When the camera 506 tracks the marker 604, the surface element is input to the computer 502. The center point of the surface can be determined as the center position of the four markers, and the orientation of the surface can be determined as the direction perpendicular to the plane determined from the four markers. Since the plane is uniquely determined if there are three markers, the number of markers may be three, but in that case, tracking cannot be performed if any one of the markers cannot be photographed. Therefore, four markers are employed in this embodiment. Note that the number of markers may be more than four.

  As shown in FIGS. 5 and 6, the present embodiment employs a motion capture device that photographs a marker with a camera, but any virtual reality technique can be employed. For example, a coil may be used as the input device, and a magnetic-based three-dimensional input device that detects a magnetic field generated from the coil may be used. Further, by providing force feedback to the input device, force information is also given regarding the interaction between the object in the virtual space and the user. In addition, as an output device, by displaying a virtual object with an HMD in accordance with a two-dimensional barcode printed on paper, the virtual object can be displayed superimposed on the real space, and the sense of immersion in the three-dimensional virtual space can be enhanced. .

  Although it is preferable to adopt a user interface using virtual reality technology such as a three-dimensional input device, a virtual space is displayed by a flat display or the like, or a three-dimensional input device such as a mouse is used to display the virtual space. You may enter.

  FIG. 7 is a diagram illustrating functions realized by the CPU 402 of the three-dimensional modeling system 400 executing a computer program. That is, the three-dimensional modeling system includes a surface element input unit 701, a surface element editing unit 702, a surface element storage unit 703, a three-dimensional model determination unit 704, and an image generation unit 705 as functional units.

  The surface element input unit 701 is a functional unit that receives an input of a new surface element from the user. As shown in FIG. 1, surface elements are represented by points and orientations. When the motion capture device as shown in FIGS. 5 and 6 is used, the center position of the plurality of markers 604 of the input device 508 is set as the center point of the surface element, and the direction perpendicular to the plane defined by the plurality of markers 604 is the surface. Get as the orientation of the element.

  The surface element storage unit 703 stores input surface elements. Specifically, as shown in FIG. 8, the coordinates of the center point and the orientation vector are stored for each plane element. The orientation of the surface element may be specified and stored by two declination angles (zenith angle and azimuth angle).

  The surface element editing unit 702 is a functional unit that changes the center point or orientation of an input surface element. By changing the center point of the surface element, the parallel movement of the surface element can be realized. Moreover, rotation of a surface element is realizable by changing the direction of a surface element. When the surface element is edited by the surface element editing unit 702, the information in the surface element storage unit 703 is updated.

  The three-dimensional model determination unit 704 generates a three-dimensional shape as an area surrounded by a plurality of surface elements stored in the surface element storage unit 703. When the surface elements intersect, the surface elements are each divided into two regions by the intersection line. Among the divided areas, a three-dimensional shape is determined by leaving an area including the center point of the surface element and trimming the area that does not include the area element. At this time, the vertex coordinates of the three-dimensional shape are obtained and stored in the storage device. A more detailed algorithm for determining the three-dimensional shape will be described later. The 3D model determination unit 704 may generate a 3D model each time a surface element is added or edited, or generate a 3D model in response to an explicit instruction from the user. May be.

  The image generation unit 705 is a functional unit that generates image data for displaying the 3D model determined by the 3D model determination unit 704 on the display. The image data generated by the image generation unit 705 is sent to the output unit 410 and presented to the user.

<Processing>
FIG. 9 is a flowchart showing a process flow of the three-dimensional modeling method according to the present embodiment. First, an input for adding a surface element or an input for editing an existing surface element is received from the user (S901). A surface element is added by designating the center point and orientation of a new surface element. Further, the surface element is edited by changing the center point or orientation of the existing surface element.

  When the surface element is added or edited, the three-dimensional model determination unit 704 determines a three-dimensional shape determined by the input surface element (S902). Details of this processing will be described later in detail with reference to FIGS. By this processing, each vertex coordinate of the three-dimensional shape is obtained. Then, the image generation unit 705 generates image data to be displayed on the display device (S903), and displays the image on the display device (S904).

  FIG. 10 is a flowchart illustrating details of the three-dimensional shape determination process performed by the three-dimensional model determination unit 704 in step S902. First, the three-dimensional model determination unit 704 obtains the distance between the surface elements for all combinations of the surface elements stored in the surface element storage unit 703 (S1001). The distance between the surface elements can be obtained as the distance between the center points of the surface elements. Then, the following processing is executed in order from a set of surface elements (surface element pair) having a smaller distance between the surface elements. That is, an intersection line of a set of surface elements is obtained (S1002), and among regions divided by the intersection line, a region including the center point of the surface element is left and a region not including the center point is trimmed (S1003). Note that when the surface elements do not intersect with each other or when the surface elements intersect with each other in the already trimmed region, the process of step S1003 is not executed.

  This will be described according to a specific example shown in FIG. Fig.11 (a) shows the state by which six surface element AF is arrange | positioned. This figure is a plan view of the three-dimensional virtual space as viewed from above, and the surface elements A to F are perpendicular to the paper surface. In addition, the square in the figure represents the center point of each surface element.

  The three-dimensional model determination unit 704 obtains the distance between the center points for each combination of the six surface elements. Here, it is assumed that the distance between the surface element A and the surface element B is the smallest. Therefore, first, a region constituting a three-dimensional shape is determined for the combination of the surface elements A and B. As shown in FIG. 11B, the surface element A is divided into a region A1 and a region A2 by the intersection line of the surface elements A and B. Similarly, the surface element B is also divided into regions B1 and B2 by intersection lines. Here, among the divided areas, the areas including the center point of the surface element (areas A1 and B1) are left, and the areas not including the center point of the surface element (areas A2 and B2) are excluded (trimmed). In this way, the area indicated by the thick line in FIG. 11B is provisionally determined as the area constituting the three-dimensional shape.

  Next, it is assumed that a combination having a small distance between the surface elements is a combination of the surface element B and the surface element C. Therefore, next, for the combination of the surface element B and the surface element C, the region constituting the three-dimensional shape is similarly determined. As shown in FIG. 11C, the area B1 of the surface element B is divided into an area B11 and an area B12 by an intersection line with the surface element C. The surface element C is divided into a region C1 and a region C2 by a line of intersection with the surface element B. Among these regions, the region B12 and the region C2 that are regions not including the center point of the surface element are trimmed, and the region B11 and the region C1 that are regions including the center point of the surface element are defined as regions constituting the three-dimensional shape. Make a provisional decision.

  Next, it is assumed that a combination having a small distance between the surface elements is a combination of the surface element A and the surface element D. Similarly to the above, as shown in FIG. 11 (d), the area A12 and the area D2 that do not include the center point of the surface element among the areas divided by the intersection line are trimmed, and the center of the surface element is obtained. The region A11 and the region D1 that are included regions are provisionally determined as regions constituting a three-dimensional shape.

Next, it is assumed that a combination having a small distance between the surface elements is a combination of the surface element E and the surface element F. Similarly to the above, as shown in FIG. 11E, among the regions divided by the intersection line, the region E2 and the region F2 that do not include the center point of the surface element are trimmed, and the center of the surface element is obtained. A region E1 and a region F1 that are included regions are provisionally determined as regions constituting a three-dimensional shape.

  Next, it is assumed that a combination having a small distance between the surface elements is a combination of the surface element D and the surface element E. Similarly to the above, as shown in FIG. 11 (f), among the areas divided by the intersection lines, the area D 11 and the area E 11 that are the areas including the center of the surface element are provisionally determined as the areas constituting the three-dimensional shape. To do. Next, it is assumed that a combination having a small distance between the surface elements is a combination of the surface element C and the surface element F. Similarly to the above, as shown in FIG. 11F, among the areas divided by the intersection line, the area C11 and the area F11 including the center of the surface element are provisionally determined as the areas constituting the three-dimensional shape. To do.

  In this way, after processing for all combinations of surface elements, the remaining surface element regions are determined as surface regions constituting a three-dimensional shape.

  In the above description, the combination of all the surface elements is not described. However, for example, since the surface element A and the surface element C do not intersect with each other, the trimming process is not performed. Further, for example, if the distance between the surface elements B and E is larger than the distance between the surface elements B and A and the distance between B and C, the surface element B will be shown in FIG. Trimming is performed as shown in (d), and the surface element B after trimming does not intersect with the surface element E. Therefore, in such a case, the surface element trimming process is not performed for the combination of the surface elements B and E.

  Another example will be described with reference to FIG. In FIG. 12A, three surface elements A to C are arranged, and the distance between the surface elements is set to BC, AC, and AB in order from the smallest. First, processing is performed on the combination of the surface elements B and C, and a part of the surface elements B and C is trimmed as shown in FIG. Next, processing is performed on the combination of the surface elements A and C, and a part of the surface element A-C is trimmed as shown in FIG. Although the process is finally performed on the combination of the surface elements A and B, the surface elements A and B after trimming in the processes so far do not intersect with each other, and therefore, no particular process is performed on this combination.

  When the number of surface elements increases and the spatial positional relationship becomes complicated, it is not obvious what polyhedron is configured from the surface elements, and it is difficult to determine the polyhedron uniquely. In the present three-dimensional modeling system, a polyhedron can be uniquely determined by an algorithm as described above in a manner that is easy for the user to understand.

  Since the region constituting the three-dimensional shape is determined by the algorithm as described above, the final three-dimensional shape changes depending on the positional relationship between the center points of the surface elements even if the arrangement of the surface elements is the same at first glance. This will be described with reference to FIG. 13A to 13C, three surface elements are arranged, and the geometric arrangement is the same in any case. However, in these arrangements, the position of the center point of each surface element is different, and therefore the distance between the surface elements (the distance between the center points) is different. In FIG. 13A, B-C, A-B, and A-C are in order from the smallest distance between the surface elements. In FIG.13 (b), it is AB, BC, and AC in an order from the thing with the small distance between surface elements. In FIG.13 (c), it is AC, BC, and AB in an order from the thing with the small distance between surface elements. Due to such differences, the order in which the regions constituting the three-dimensional shape are determined is different, so that the finally obtained three-dimensional shape is different.

<Operation and effect of this embodiment>
According to the three-dimensional modeling system according to the present embodiment, a user can model a three-dimensional shape by arranging faces. Since a three-dimensional shape can be created simply by arranging the surfaces, the burden on the user is greatly reduced compared to a method of inputting vertex coordinates. Also,
Since only one surface element is added to the input three-dimensional shape, a shape trimmed by the surface element can be created, which also reduces the burden on the user. In addition, when an existing surface element is moved or rotated, the burden on the user is reduced in that the flatness of each surface of the three-dimensional shape is maintained. This is because in the 3D modeling system based on vertices, it is necessary to move each coordinate so as to maintain flatness, but in this system, it is not necessary for the user to make such considerations.

  In addition, the three-dimensional modeling system according to the present embodiment provides a suitable algorithm for determining a three-dimensional shape from a plurality of surface elements. In order to determine the three-dimensional shape from the surface element, a method of allowing the user to specify a pair of surface elements having intersecting lines is also conceivable. However, if the algorithm of the present system is used, 3 A dimensional shape can be determined.

  The three-dimensional modeling system according to the present embodiment can be particularly suitably used when inputting a three-dimensional shape composed of a relatively small number of planes such as a building.

(Second Embodiment)
In the present embodiment, a plurality of surface elements are grouped so that editing such as movement and rotation can be performed collectively. The 3D modeling system according to the present embodiment is basically the same as that of the first embodiment except that grouping is possible. In the following description, differences from the first embodiment will be mainly described.

  The grouping of a plurality of surface elements will be described with reference to FIG. In FIG. 14, three surface elements 1410, 1420, 1430 are shown. The center points of the surface elements are 1411, 1421, and 1431, respectively, and the orientations are 1412, 1422, and 1432, respectively. The user can select and group these three surface elements via the surface element editing unit 702. Here, a case where three surface elements are grouped will be described as an example, but it can be easily understood that the same applies when two or four or more surface elements are grouped.

  When grouping a plurality of surface elements, the user selects one surface element from among the plurality of surface elements as a surface element representing the group. Hereinafter, the surface element representing the group is referred to as a “core” of the group. Then, when the user edits the center point and orientation of the surface element that is the core of the group, the entire group can be operated.

  Specifically, by moving the center point of the nucleus of the group, the entire group is translated while maintaining its relative arrangement. Internally, the above processing can be realized by applying the same translation operation to the center points of all the surface elements constituting the group.

  Further, by changing the orientation of the group nucleus, the entire group rotates while maintaining its relative position. Internally, the above processing can be realized by applying the same rotation operation to the orientations of all the surface elements constituting the group.

  15 and 16 are diagrams for explaining operations that can be performed by grouping. In Fig.15 (a), the five surface elements 1501-1505 which comprise a rectangular parallelepiped are included. By grouping and moving these five surface elements, as shown in FIGS. 15B and 15C, only a rectangular parallelepiped can be translated in a lump. Further, in FIG. 16A, five surface elements 1601 to 1605 are grouped, and a rotation operation is performed on the group, so that the inclinations of these five surface elements are collectively shown in FIG. 16B. Can be changed.

  When the group structure is introduced, it is necessary to slightly change the process (step S902 in FIG. 9 and FIG. 10) for determining the area constituting the three-dimensional shape from the first embodiment. First, an area determination process is performed only on the grouped surface elements first to determine a group area. Then, the area of the group is regarded as one element, and the area is determined with other elements (surface elements or other groups). Therefore, even when a plurality of surface elements are arranged in the same manner, the final three-dimensional shape varies depending on the presence or absence of grouping.

  FIG. 17 is a diagram for explaining that the finally obtained three-dimensional shape varies depending on the presence or absence of grouping. FIG. 17A shows a three-dimensional shape when the three surface elements A to C are not grouped. Here, it is assumed that the distance between the surface elements A and C is the shortest, and the distance between the surface elements B and C is next short. In this case, the shape as illustrated is determined by performing the processing as described in the first embodiment. The surface elements A to C shown in FIG. 17B have the same center point and orientation as those in FIG. 17A, but the surface elements B and C are grouped with B as the nucleus. . Therefore, first, a region is determined by performing trimming processing based on the two surface elements B and C, and further, trimming by the surface element A is performed. The resulting shape is different from that in FIG. 17A where no grouping is performed.

  FIG. 18 is a diagram illustrating another example for explaining the difference depending on the presence or absence of grouping. In FIG. 18A, the three surface elements A to C are not grouped, but in FIG. 18B, the surface elements A and C are grouped with A as the nucleus. In FIG. 18B in which the grouping is performed, the area determination process is first performed based on the surface elements A and C, and further, the area determination process is performed considering the surface element B. The shape to be obtained is different from that in FIG.

  Groups can be nested. That is, one group can be a component of another group. That is, the group may be a combination of surface elements, a combination of surface elements and groups, or a combination of groups. Therefore, more generally, the three-dimensional model constituting the entire scene is expressed as a tree structure. FIG. 19 is an example of a tree structure graph showing the structure of the entire scene. In FIG. 19, the leaf node at the end represents a surface element, the intermediate node represents a group, and the root represents the entire scene. Here, a group G1 composed of four surface elements P1 to P4 and a group G2 composed of two surface elements P5 and P6 are defined. A scene S is defined from the groups G1 and G2 and the surface elements P7 and P8.

  The area determination process in the present embodiment will be described in more detail. In the present embodiment, the entire scene is expressed as a tree structure as shown in FIG. In determining the geometry of the entire scene, the entire geometry is determined by performing region determination processing between child node groups under each intermediate node while tracing this tree structure bottom-up. Although different from the first embodiment in that a group can be included as a child node, the region determination process (FIG. 10) in the first embodiment is executed with the child node as one element.

  In the first embodiment, in step S1001 in FIG. 10, the distance between the surface elements is obtained for all combinations of the surface elements, and the processing is performed in order from the surface element pairs with the smallest distance. In this embodiment, the distance between elements is calculated | required about all the combinations of the element (namely, group or surface element) which comprises a group. At this time, the distance of the group is obtained with reference to the center point of the nucleus. That is, the distance between the group and the surface element is obtained as the distance between the center point of the group nucleus and the center of the surface element. The same applies to the distance between groups. Then, the region determination process is performed in order from the element pair with the smallest distance.

In the loop of steps S1002 to S1003, in this embodiment, there are three possible combinations of elements constituting a group: two surface elements, one group and one surface element, and two groups. Since the process in the case of surface elements may be the same as that of the first embodiment, the description is omitted. Hereinafter, the area determination process based on the group and the surface element and the area determination process based on the two groups will be described in order.

  FIG. 20 is a diagram for explaining region determination processing for an element pair of a group and a surface element. FIG. 20A is a diagram illustrating a scene including a group G composed of surface elements A and C and a surface element B, as illustrated in FIG. The black circle in the figure represents the center point of each surface element. Here, it is assumed that the surface elements A and C are grouped with the surface element A as a core. Group G has a region as shown in FIG. The region determination process based on the region of the group G and the surface element B is basically the same as the method of the first embodiment, and the center point of the surface element among the regions divided by the intersection line of the surfaces Trim the one that does not contain the center point, leaving the one that contains. However, the shape of the group that is grouped at this time is different from the first embodiment in that trimming is performed so as to leave the center point of the nucleus while paying attention to the center point of the nucleus of the group. .

  As shown in FIG. 20C, the surface element B is divided into regions B1 and B2 by intersection lines. Then, the region B1 including the center point of the surface element B is left, and the region B2 is trimmed. The group G is divided into regions G1 and G2 by intersecting lines, but the region G1 including the center point of the surface element A that is the core is left, the region G2 is trimmed, and finally in FIG. The shape shown is obtained.

  When the core of the group G is the surface element C, the region G2 is left and the region G1 is trimmed, so that the finally obtained shape is as shown in FIG.

  FIG. 21 is a diagram for explaining region determination processing when groups are used as element pairs. FIG. 21A is composed of two groups A and B each having a U-shape. In the group A, as shown in FIG. 21B, three surface elements A1 to A3 are grouped, and the surface element A1 is the core. In the group B, as shown in FIG. 21C, the three surface elements B1 to B3 are grouped, and the surface element B1 is a nucleus.

  In the area determination process for groups, intersection lines are calculated for all pairs between faces in the geometry forming the group, and each face is divided into areas by the intersection lines. For example, in FIG. 21A, the surface 2102 is divided into three regions by intersecting lines with the surface 2105 and the surface 2106. Divided regions are also determined for other surfaces.

  Then, starting from the core of each group, the area to be left is determined while expanding the surrounding area. At this time, processing is performed in the order from the closest distance from the nucleus, and the area is expanded until it intersects (or contacts) the area of the partner group. For the group A, first, a divided area from the periphery of the nucleus A1 to the next intersection line is determined as an area to be left. That is, the areas 2102a and 2103a in FIG. 20D are determined as areas to be left. Similarly for the group B, the areas 2105a and 2106a are determined as areas to be left. Here, the region 2103a expanded from the group A nucleus and the region 2105a expanded from the group B nucleus intersect each other. Therefore, the area expansion for the surface 2103 and the surface 2105 ends here. Since the area 2102a and the area 2106a do not intersect with the partner group, the area 2102a and the area 2106a are continuously subjected to the area expansion process.

When the area of group A is further enlarged, the area 2102b which is the next divided area is determined as an area to be left. For group B, the region 2106b is determined as the region to be left. Here, since these areas 2102b and 2106b intersect with the partner group, the area expansion ends. As a result, all the region enlargement processes are completed, and the region based on the group A and the group B is determined as a shape as shown in FIG.

  According to the present embodiment, by introducing a group, processing such as movement and rotation can be performed on a plurality of surface elements in a single operation, so that the burden on the user is reduced. Further, the shape can be easily determined by grouping. When the grouping is not performed, the shape finally obtained differs depending on the positional relationship of the surface elements (see, for example, FIG. 13). However, by performing the grouping, depending on the positional relationship with the surface elements outside the group. The shape of the group can be made constant (for example, see FIG. 15).

(Third embodiment)
In the first embodiment, the user creates a polyhedron by arranging surface elements one by one. However, in actual modeling, there are primitive shapes that are often used. A primitive shape that is often used is defined as a group composed of a plurality of surface elements and stored in a memory so that the user can select and arrange the defined group via the surface element input unit 701. This reduces the input burden. It is also preferable to register not only the groups registered in advance but also the groups created by the user so that they can be used later.

  The predefined group shape may be arbitrary, but for example, a shape as shown in FIG. 22 is conceivable. FIG. 22A shows a shape in which a corner is expressed by a combination of two surfaces. FIG. 22B shows a shape that represents a pillar placed on a plane by combining three surfaces. FIG. 22 (c) represents a rectangular parallelepiped that is obtained by combining five surfaces. FIG. 22D shows a shape representing a semi-cylinder that is placed on a plane by combining seven surfaces. In addition to the above, arbitrary various shapes can be registered in advance.

  In this way, the user can easily arrange shapes that are frequently used or shapes that are difficult to create. In particular, if a combination of planes is used as shown in FIG. 22D, approximate curved surfaces can be easily arranged.

(Modification)
In the above description, a plane is used as the surface element. However, it is also preferable to adopt a curved surface as the surface element. Examples of the curved surface include a cylindrical surface, a spherical surface, and a paraboloid, but a curved surface having an arbitrary shape can also be used. When a curved surface is adopted as the surface element, the surface element is specified by inputting the position, the direction of the normal at that position, and the parameters that characterize the curved surface. Parameters that characterize a curved surface include a radius of curvature for a cylindrical surface or a spherical surface, and a focal length for a parabolic surface.

701 Plane element input unit 702 Plane element editing unit 703 Plane element storage unit 704 Three-dimensional model determination unit 705 Image generation unit

Claims (17)

A 3D modeling method in a 3D modeling system,
An input step for receiving an input of a surface element;
A modeling step for generating a three-dimensional model as a region surrounded by a plurality of input surface elements;
Including a three-dimensional modeling method. In the input step, an input of a surface element is accepted by specifying a point and a direction,
The three-dimensional modeling method according to claim 1. A step of accepting an instruction to move or rotate the input surface element;
Regenerate the 3D model based on the moved or rotated surface elements;
The three-dimensional modeling method according to claim 1 or 2. Further comprising accepting a designation for grouping the plurality of face elements;
When a movement or rotation instruction for a plurality of grouped surface elements is received, the specified movement or rotation is applied to the grouped surface elements.
The three-dimensional modeling method according to claim 3. The modeling step includes
Obtaining a distance between surface elements for all combinations of a plurality of surface elements;
Determining a surface area constituting the three-dimensional model based on the line of intersection of the surface element pairs in order from the surface element pair having the smallest distance;
The three-dimensional modeling method according to claim 1, comprising: The surface element receives input by specifying a point and a direction,
In the step of determining the surface region, a region including the point is determined as a surface region constituting the three-dimensional model among the regions divided by the line of intersection of the surface element pairs.
The three-dimensional modeling method according to claim 5. Further comprising accepting a designation for grouping the plurality of face elements;
The modeling step includes
Determining a surface area constituting a three-dimensional model for a plurality of grouped surface elements;
Determining a surface area constituting a three-dimensional model with another surface element by regarding the surface area determined for the grouped surface elements as one element;
The three-dimensional modeling method according to claim 5 or 6, comprising: Further comprising the step of grouping and storing in advance a combination of a plurality of surface elements;
In the input step, it is possible to select and arrange a plurality of grouped surface elements stored in advance,
The three-dimensional modeling method according to claim 1.   The computer program for making a computer perform each step of the method in any one of Claims 1-8. Surface element input means for receiving input of surface elements;
Three-dimensional model determining means for generating a three-dimensional model as a region surrounded by a plurality of input surface elements;
A three-dimensional modeling system comprising: The surface element input means receives an input of a surface element by specifying a point and a direction,
The three-dimensional modeling system according to claim 10. A surface element editing means for receiving an instruction to move or rotate the input surface element;
The three-dimensional model determining means regenerates the three-dimensional model based on the moved or rotated surface element.
The three-dimensional modeling system according to claim 10 or 11. The surface element editing means accepts designation for grouping a plurality of surface elements,
When a movement or rotation instruction for a plurality of grouped surface elements is received, the specified movement or rotation is applied to the grouped surface elements.
The three-dimensional modeling system according to claim 12. The three-dimensional model determining means includes
For all combinations of multiple surface elements, find the distance between the surface elements,
In order from the surface element pair with the smallest distance, the surface region constituting the three-dimensional model is determined based on the intersection line of the surface element pair.
To generate a three-dimensional model,
The three-dimensional modeling system according to any one of claims 10 to 13. The surface element receives input by specifying a point and a direction,
The three-dimensional model determining means determines a region including the point among the regions divided by the line of intersection of the surface element pairs as a surface region constituting the three-dimensional model.
The three-dimensional modeling system according to claim 14. The surface element editing means accepts designation for grouping a plurality of surface elements,
The three-dimensional model determining means includes
For a plurality of grouped surface elements, determine the surface region that constitutes the three-dimensional model,
A surface area determined for a plurality of grouped surface elements is regarded as one element, and a surface area constituting a three-dimensional model is determined with other surface elements.
To generate a three-dimensional model,
The three-dimensional modeling system according to claim 14 or 15. Storage means for storing in advance a group of combinations of a plurality of surface elements;
The surface element input means can select and arrange a plurality of grouped surface elements stored in advance.
The three-dimensional modeling system according to any one of claims 10 to 16.

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