JPH0944701A - Object data conversion method in three-dimensional space - Google Patents

Abstract

PROBLEM TO BE SOLVED: To operate only a part of an object in a three-dimensional CG space by converting the data of a flat structure having no hierarchical structure into the data having a hierarchical structure. SOLUTION: An object reading means 2 reads the desired object data out of an object storage means 1, and a histogram generation means 4 generates the histograms projected for every coordinate axis based on the parameter that is set by a parameter setting means 3 for division. An object division means 5 divides a three-dimensional space including the object data at every area where the prescribed grade value is set. If a plane forming the object data is included in plural divided three-dimensional spaces, these spaces are regarded as one of divided three-dimensional spaces. Then the divided three- dimensional spaces and the three-dimensional space regarded as one of divided three-dimensional spaces are outputted after a verification means 6 checked the presence or absence of the operating interference among the parts included in the object data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for converting object data in a three-dimensional space for dividing object data having no hierarchical structure into parts.

[0002]

2. Description of the Related Art Many walk-through systems have been developed for verifying the layout of buildings and equipment by using three-dimensional computer graphics before they can be actually used.
It is being used for design.

The data used for these walkthroughs is often created using a dedicated modeler. However, in order to make it close to reality, it is necessary to recreate the data in detail, and the cost of data entry is high, such as the fact that the data created with time and effort cannot be reused in the post-design process, which is a problem. It has become to.

In order to improve this, a method of converting data created by three-dimensional CAD for CG and using it is being studied. In these conversion methods, each three-dimensional CA
A command peculiar to the D data is converted into a surface (polygon) forming the surface of the object. When information such as a normal vector is missing in the three-dimensional CAD data, the front and back of the surface are estimated from the arrangement of the vertex coordinates forming the surface (polygon),
It is necessary to add a normal vector.

Three-dimensional C created by such conversion
The data of G is data in which the entire object is collected. For example, the data of an object such as a chair is static data in which the backrest, height, etc. do not change. When displaying an object that does not move, there is no particular problem even if the whole object is put together. In other words, there is no problem if it exists as an obstacle.

However, when an instruction is given to a part of a three-dimensional object having a movable part such as walking a human body or rotating a seat part of a swivel chair, the whole object is moved. There is a problem that it can not be dealt with if the data is organized.

In order to operate a part of a three-dimensional object, an object having a hierarchical structure must be created for each individual part in advance. Three-dimensional C according to this hierarchical structure
Data is exchanged with the AD data for each part of each layer. Alternatively, the CG designer manually performs the work of dividing the integrated three-dimensional CAD data and assembling the hierarchical structure. Such manual work can be very complicated.

That is, in the conventional method, it was not possible to make a functional movement by using the three-dimensional CAD data which was unintentionally created in advance. This is a barrier when reusing the three-dimensional CAD.

Further, by using an object having a hierarchical structure,
In order to create animation, it is necessary to give motion to each layer. This movement collides with the parts of other layers (interference)
It must be given a suitable range of motion so that it will not fall. In order to do this, (1) the CG designer checks the consistency and sets it, or (2) the method of performing the interference check at the time of display to prevent the mismatch.

Since the method (1) is performed by a human, it is troublesome. On the other hand, the method (2) has a problem in that the calculation cost of the interference check is high and thus the computer cost is high.

[0011]

In the above-mentioned conventional method, since data is created without setting the hierarchical structure in advance, it is difficult to carry out processing such as partial movement. Furthermore, it took time to give the movable range by hand or to calculate it with a computer cost.

On the other hand, the object of the present invention is to analyze data having no hierarchical structure and automatically convert it into data having a hierarchical structure. Furthermore, it is an object to automatically determine the movable range by performing interference check on the converted data in advance.

[0013]

In order to solve the above problems, the invention of the present application generates object histograms by projecting object data in a three-dimensional space composed of a plurality of planes for each coordinate axis. When the three-dimensional space containing the object data is divided at a position where the histogram has a predetermined gradient value, and among the divided three-dimensional spaces, the planes forming the object data are included in a plurality of divided three-dimensional spaces. , 1 that is obtained by dividing this 3D space
It is characterized in that it is regarded as one three-dimensional space, and the divided three-dimensional space and the three-dimensional space regarded as one divided space are output as parts of the object data.

[0014]

[Function] By converting flat data having no hierarchical structure into data having a hierarchical structure, three-dimensional C
It is possible to operate only a part of the object in the G space.

Since such data conversion is automatically performed, the labor of creating hierarchical data can be greatly reduced. In addition, since the movable range of each part is automatically set, even if the CG designer does not make any particular setting, consistent movement is guaranteed without performing interference check at the time of display. Computer processing can be significantly reduced.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of the same embodiment. First, the object reading unit 2 reads desired object data composed of a plurality of planes stored in the object storage unit 1. The histogram generating means 4 projects the object data read by the object reading means 2 for each coordinate axis based on the parameters for division set by the parameter setting means 3 to generate a histogram. Histogram generating means 4
Based on the histogram generated by the above, the object dividing unit 5 divides the three-dimensional space including the object data at a position having a predetermined gradient value, and configures the object data in the divided three-dimensional space. When the plane to be included is included in a plurality of divided three-dimensional spaces, the plurality of three-dimensional spaces are regarded as one divided three-dimensional space, and the divided three-dimensional space and the three-dimensional divided spaces are regarded as the three-dimensional space. The verification means 6 checks the presence or absence of interference in the operation of the parts of the object data in the space and outputs the space. Next, an automatic hierarchical structure creating method according to the present invention will be described. As an example of office chair data as a three-dimensional object used in CG, an automatic hierarchical structure creating method for converting flat chair data having no hierarchical structure will be described.

2 and 3 show flow charts of the process of the automatic hierarchical structure creating method. Hereinafter, description will be given along this flow chart. In step 1, data is loaded from disk into memory. This data is a polygonal object as shown in FIG. 4, and the data is composed of the coordinates and color of each surface.

In step 2, the following initial parameters are set. The projection method is used as the structural analysis method. In this method, a result of projecting an object on a certain surface is processed by a histogram and analyzed, and a projection plane and a histogram division width are required as parameters.

Here, assuming that the y-axis is the basic axis, the x-axis,
The z-axis and the y-axis are projected in this order. The initial width of the histogram is the average of the diagonal lengths of all polygons.

Specifically, if the vertex of a polygon is (x
0, y0, z0), (x1, y1, z1), (x2, y
2, z2), x0, x1, x3 on the x-axis
The frequency (histogram) is incremented by 1 at each of the coordinates. The same applies to the y-axis and the z-axis. This kind of work is performed on all polygons. As a result, the histogram of a portion having many polygons becomes high.

Furniture such as chairs has horizontal / vertical planes for its main surfaces, for example, a seating surface and a back surface, for human use. In such a case, it is possible to obtain a projection result suitable for hierarchization by using the y axis as a basis. If you don't get enough results for stratification,
In the next step 3, the parameters are changed.

In step 3, the projection plane and the histogram width are changed in the second and subsequent calculations.
In step 4, the object is projected, and fitting processing is performed on the created histogram to determine the division plane. The division is performed at the point where the gradient value is the steepest.

The results performed on the example chair are shown in FIG. FIG. 6 shows the result of fitting processing performed on the result of projection of chair data made by three-dimensional CAD on the x-axis and the y-axis.

In the projection on the x-axis, since the number of polygons in the column of the chair is large, the histogram at the center is high. On the other hand, when the division plane is determined, both ends of the histogram and the vicinity of the center where the gradient is steep are candidates for division. The division points are indicated by dotted lines in FIG.

In the projection on the y-axis, the number of polygons at the back of the chair, the seat, and the casters is large, so that a histogram having peaks at these three locations is obtained. Therefore, there are four dividing points at both ends and a steep gradient. These are
Indicated by dotted lines.

As a result, the chair was divided into 15 spaces. In step 5, the vertex coordinates of each polygon are divided into each space divided by the single or plural dividing surfaces determined in step 4. When one polygon spans a plurality of divided spaces, these spaces are redefined as one space.

In the example of FIG. 6, the chair is divided into 15 spaces. However, there are polygons forming the back part of the chair that extend over three spaces 1, 2, and 3, so that the spaces 1, 2, and 3 are integrated to form the space 1.

Similarly, the spaces 7, 8 and 9 are integrated into the space 7
Then, the spaces 13, 14, and 15 are integrated into the space 13. On the contrary, since there are no polygons in the spaces 4, 6, 10 and 12, such space is excluded.

Although not clearly shown in FIG. 6, there are cases where the support columns of the chair are connected to the spaces 5 to 2. In such a case, since the column and the spine are separated by the projection in the z-axis direction, the spaces 1, 2, and 3 are integrated with respect to the spine, but the space 2 and the space 5 are integrated with respect to the column. In step 6, the termination condition is checked. As an end condition, it is possible to consider whether or not the expected number of divisions has been reached. This can be expressed as follows.

[0030]

[Equation 1] (D: Expected number of divisions, d: Number of divisions, α: Convergence range) The expected number of divisions D is the number of parts to be divided at this stage. The convergence range α is a measure of how much the division is stopped with respect to the expected number of divisions. If α is small, the number of divisions d must be almost the same as the expected number of divisions to complete the process.

For example, in the case of a chair, if it is expected that the chair will be divided into about 5, the expected division number D is set to 5. If α is 10%, the number of divisions d
If is not 5, it cannot converge.

In the example of FIG. 6, since the number of divisions has become 5 successfully, the process can be ended. If you cannot finish, step 3
Returning to step 1, the parameters such as the projection width are corrected, and steps 4 to 6 are repeated.

In step 7, it is determined whether or not to further hierarchize each part of the divided and hierarchized data. If further hierarchization is performed, the data to be processed is limited to the divided parts of the data, and steps 2 to 6
repeat.

That is, in the example of FIG. 6, the process could be divided into five parts up to step 6. However, casters, etc.
Not yet split from the leg part. In order to divide this, it is necessary to divide the space 13 (the space formed by integrating the spaces 13, 14, and 15 in FIG. 6) again by the procedure of steps 2 to 6.

As described above, the data having no hierarchical structure as shown in FIG. 4 is converted into the data having a hierarchical structure as shown in FIG. Furthermore, in order to move an object as an animation, it is necessary to have a value indicating in which range each part can move. FIG. 7 is a flowchart of the movable range calculation in the processor 1.

In step 9, first, the part number i is initialized (set to 0) and the movable ranges αk, βk, γk (k is 1 to N, N is the total number of parts) (a sufficiently large value, for example, 10, 000).

In step 10, the value is incremented by 1 and it is determined in step 11 whether the movable range has been calculated for all parts. If the movable range is set to 0 by the interference check with other parts in the previous step, it is not necessary to execute step 13 and subsequent steps, so check it (step 1
2).

In step 13, a part number j other than the target part i is set. First, it is determined whether or not the component j is within a range sufficiently close to the movable range of the component i by performing an interference check on the bounding boxes (circumscribing rectangular parallelepipeds) of both components (step 14).

If there is no interference, there is no need to consider the part j, and the process moves to the next part (step 15). If they interfere with each other, an interference check is performed on both components themselves (step 17). If they interfere, the parts i and j cannot move.
The value 0 is set to the respective movable range αi, βi, γi, α
It is set to j, βj, and γj (step 18). Part j
Is also set, so that in the subsequent steps, the part j
With regard to (2), it takes time and effort to calculate the movable range (the determination is made in step 12).

When the component i and the component j do not interfere with each other, the component i is rotated around the x-axis, the y-axis, and the z-axis to calculate the value when the component i interferes with the component j. (Step 19). The calculation is done by adding 1 °, or 10
Various methods are possible, such as a method of adding by each degree and subtracting by 1 degree from the time of interference, to obtain.

If the value is smaller than the movable range calculated by the interference check with other parts, the value is set to the corresponding value (αi, βi, γi) (step 20). The initial values of αi, βi, γi are step 9,
Since it is set to a sufficiently large value, the value calculated first replaces it.

The same interference check is performed by changing the parts j one after another. The remaining movable ranges αi, βi, γi are the movable ranges of the part i. Similarly, for other parts, steps 11 to 20 may be repeated. (Modification) In the first embodiment, a method using a histogram obtained by projecting polygon vertex data has been described. However, there may be cases where the histogram alone cannot be sufficiently divided. In such a case, as shown in FIG. 4, a more accurate division method can be considered by combining attribute information such as texture and color included in the three-dimensional data. In other words, when the data is divided in step 5, if the division is not clear, if the texture and the color that are the attribute information of the polygon are the same, they are regarded as the same part and divided.

Further, the parameter change in step 3 allows the projection plane, the histogram width, etc. to be changed interactively while observing the histogram as a result of the division in step 5 as shown in FIG. Modifications such as are also possible.

Further, it is possible to label each layer with respect to the layered structure as shown in FIG. 5 obtained as a result of the analysis. The hierarchical structure in FIG. 5 can be adapted to, for example, the Invenvtor format, which is becoming the industry standard.

[0045]

According to the present invention, it is possible to convert only a part of the user into an operable object in the three-dimensional CG space without any particular effort by the user. In addition, since the user can also obtain the movable range of the part without much trouble, anyone can reuse the three-dimensional data and easily generate the animation.

[Brief description of drawings]

FIG. 1 is a block diagram of hardware according to an embodiment of the present invention.

FIG. 2 is a flow chart of division processing according to an embodiment of the present invention.

FIG. 3 is a flowchart of division processing according to an embodiment of the present invention.

FIG. 4 is a three-dimensional object data file diagram according to an embodiment of the present invention.

FIG. 5 is a three-dimensional object data file diagram having a hierarchy according to an embodiment of the present invention.

FIG. 6 is a conceptual diagram showing a dividing method according to an embodiment of the present invention.

FIG. 7 is a flowchart for calculating a movable range according to an embodiment of the present invention.

[Explanation of symbols]

 Object storage means 1 Object reading means 2 Parameter setting means 3 Histogram generating means 4 Object dividing means 5 Verification means 6

Claims (1)

[Claims] 1. A histogram is generated by projecting object data in a three-dimensional space composed of a plurality of planes for each coordinate axis, and the generated histogram includes the object data at a position where a predetermined gradient value is obtained. If a plane forming object data is included in a plurality of divided three-dimensional spaces among the divided three-dimensional spaces, one of the divided three-dimensional spaces is defined as one divided three-dimensional space. A method for converting object data in a three-dimensional space, characterized in that the divided three-dimensional space and the three-dimensional space regarded as one divided space are output as parts of the object data.