JPH0816816A - Computer graphics display method - Google Patents

Abstract

PURPOSE:To display a natural picture at high speed in the computer graphics display of a three-dimensional model by displaying a minute model when the size of the model to be displayed on a screen is larger than a value which is previously set and an abbreviated model when it is smaller. CONSTITUTION:A computer 1001 consists of the input/definition part of the minute model 3, which executes an algorithm, controls an input unit and becomes a first storage part, an arithmetic part generating the abbreviated model 4, an allocation part storing the abbreviated model 4 and the selection part of the model to be displayed. A display controller 1002 converts a digital signal from the computer 1001 into an analog signal for display and controls a display device 1003. The size of the model to be displayed on the screen is judged with such constitution. When the size is larger than the value which is previously set, the minute model 3 is displayed, and the abbreviated model 4 when it is smaller. Thus, the small model which is not conspicuous on the screen can be abbreviated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to modeling and display technology in graphic processing, and more particularly to a computer graphics display method suitable for three-dimensional computer graphics.

[0002]

2. Description of the Related Art Conventionally, in three-dimensional computer graphics, IPSJ Transactions, Vol. 25, No. 6 (19
(1984) As described on page 948, the speed of display processing is increased by utilizing the property that individual object models occupy local areas in the entire space and the areas do not overlap each other. I'm drawing. For example, it is a method of defining a circumscribed rectangular parallelepiped for an object model to be displayed and limiting the inside of the circumscribed rectangular parallelepiped when performing a process of searching for a model in space. This eliminates the need to unnecessarily search for an area distant from the object model, thus speeding up the display process.

Further, as a display speed-up method utilizing the same property, in Japanese Patent Laid-Open No. 60-79477, the display is speeded up by limiting the search only to a rectangular area surrounding the object on the screen. Further, Japanese Laid-Open Patent Publication No. 61-139890 is a high-speed display method that utilizes the uniformity of search processing as well as limiting the search range by using the local existence of the object model.

On the other hand, computer graphics 16-
3 (1982) pp. 9-18 (Computer Graph
ics, Vol.16, No.3 (1982) pp9-18), it is possible to assign a plurality of models to the same object, and the operator can specify the detail level. By assigning different models to the same created object, the system can select and display the model with the required level of detail according to the size on the screen.

[0005]

Of the above-mentioned conventional techniques,
In the high-speed display method using the local existence of the object model,
For example, even if the object model is defined in a region far away from the viewpoint and occupies a very small area on the screen, the object model is searched in detail because the inside of the limited region is sufficiently searched. The rate of reduction of the processing time is small as compared with the case of being close. On the other hand, in a system that can display models with different levels of detail,
Although the processing can be speeded up when the object model is sufficiently far, it is necessary for the operator to create and allocate each model, and since a plurality of models are created for the same object, the work man-hour of the operator is large.

It is an object of the present invention to provide a method of displaying a natural image at high speed by computer graphic display.

[0007]

In order to achieve the above object, the present invention determines the size of a model to be displayed on the screen, and when the size is larger than a preset value, When the detailed model is displayed and the size is smaller than a preset value, the display is switched to the display of the omitted model and displayed on the display device.

Further, the detailed model and the omitted model are switched according to the moving speed of the model to be displayed, and the display is performed on the display device.

Further, when the detailed model and the omitted model are switched and displayed on the display device, the switching is performed while changing the respective transmittances of the detailed model and the omitted model.

[0010]

The size of the model to be displayed on the screen is determined, and when the size is larger than a preset value, the detailed model is displayed and the size is larger than the preset value. When the size is small, the display is switched so as to display the abbreviated model, so that a small model that is inconspicuous on the screen can be omitted, and a natural image can be displayed at high speed.

Further, since the detailed model and the omitted model are switched and displayed on the display device according to the moving speed of the model to be displayed, it is possible to omit a model having a motion which is difficult to see by the eye and a natural image is displayed. It can be displayed at high speed while realizing it.

Further, when the detailed model and the omitted model are switched and displayed on the display device, the switching is performed while changing the respective transmittances of the detailed model and the omitted model, so that the images are not suddenly switched. There is little unnaturalness above.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a diagram showing the outline of the present invention. As shown in FIG. 1A, a ray 5 passing through a screen 2 is traced from a viewpoint 1 set in a three-dimensional space, A method of displaying the detailed model 3 that is the first three-dimensional model of the object and the omitted model 4 that is the second three-dimensional model of the object on the two-dimensional screen is described. It should be noted that all of these are expressed as numerical models on a computer, and in practice C that is the display unit as a result of calculation.
Obtaining a display image such as a display 6 by a detailed model (FIG. 1B) or a display 7 by a omitted model ((FIG. 1C)) on the screen 8 of a two-dimensional display such as RT, liquid crystal, or EL. You can

FIG. 1D shows a hardware configuration for realizing the present invention. The input device 1000 is a device such as a keyboard and a tablet, and is used to input model information and display control information. The computer 1001 executes the algorithm according to the present embodiment and controls the input / output device. The input and definition unit of the detailed model serving as the first storage unit, the calculation unit that generates the omitted model, and the omitted model. And a model selection unit for displaying. The display control device 1002 converts a digital signal from a computer into an analog signal for display and controls the display device 1003. An image can be displayed on the screen by the display device 1003 which serves as a display unit. The display device may be a three-dimensional display using holography or the like.

The operation of each part of the embodiment when the present invention is realized by computer software will be described with reference to FIG. These can also be realized by hardware.

First, step 101 is a step of inputting a detailed model and visual field information necessary for display. For example, when the detailed model 3 has a rectangular parallelepiped shape with rounded corners, eight spherical elements, twelve cylindrical elements, and six cylindrical elements as shown in FIG.
It is composed of 2 plane elements. If this detailed model is called a component 1, the configuration of the graphic element can be represented by the main structure as shown in FIG.

Here, in the present embodiment, as shown in the figure, a scene is assumed to be composed of several objects, each object is also composed of several parts, and each part is composed of several parts. It is assumed that it is composed of the graphic elements of.
Then, the hierarchical level of the object is called the object level, and hereinafter, similarly, it will be called the component level and the graphic element level. Thus, the input of the detailed model is to define the shape of the three-dimensional model on the computer as a set of graphic elements. On the other hand, the input of the visual field information is to determine the position in the three-dimensional space with respect to the viewpoint 1 and the screen 2 in FIG. 1, and is input with XYZ coordinate values, for example. Furthermore, regarding the screen, the size and orientation of the screen are also entered. In addition, the minimum size required for displaying the detailed model is input in order to determine how many pixels or more the size of the object on the screen is displayed in the detailed model. In short, in this step 101, the object three-dimensional shape model information is input as detailed model information, and the visual field information such as the viewpoint / screen position for further display is also input.
This is a step of storing in the first storage unit.

Step 102 is a step of searching the tree structure data of FIG. 4 based on the detailed model information input in step 101. In this embodiment, if an abbreviated model is generated for the component level in the tree structure of FIG. 4, the tree structure of FIG. 4 is searched to detect a component level component such as the component 1. .

Step 103 is a step of algorithmically generating an abbreviated model for the input detailed model. Here, it is assumed that the detailed model is defined by a set of graphic elements as shown in FIGS. Then, as the omitted model, the circumscribed rectangular parallelepiped of the detailed model is assigned. In order to generate this circumscribed rectangular parallelepiped, as shown in FIG. 5, the maximum and minimum values when the detailed model is projected on the XYZ axes may be obtained. In the figure, the maximum value when projected onto the X axis is x _max and the minimum value is x _min, and y _max , y _min , z _max , and z _min are similarly obtained. From these maximum and minimum values, the equations of six planes as shown in FIG. 6, X = x _max , X = x _min , Y = y _max , Y = y _min , Z
= Z _max , Z = z _min . A three-dimensional model composed of these six plane equations is assigned as an abbreviated model. The input detailed model is composed of a total of 26 graphic elements as shown in FIG. 3, and each graphic element has parameters such as radius and length. On the other hand, in the generated omission model, in the case of the circumscribing rectangular parallelepiped as in the present embodiment, it can be described by six parameters for designating the above six plane equations. Therefore, in this step, the number of parameters of the detailed model is reduced. In addition, since this omitted model does not include a quadric surface such as a spherical element or a cylindrical element that is included in the detailed model, the dimension of the model is reduced. Further, the data structure is changed from the tree structure shown in FIG. 4 to that shown in FIG. Here, the detailed model 3 is a set of 26 graphic elements in FIG. 3, and the omitted model 4 is one circumscribed rectangular parallelepiped shown in FIG. That is, two models, a detailed model and an abbreviated model, are assigned to the same part.

Step 104 means repeating steps 105 to 108 for each pixel on the screen 2. The screen (screen) 2 has m × n pixels as shown in FIG. 1, and is usually matched with the display resolution of the display 1003. Therefore, m up to step 108
× n times will be repeated.

Step 105 is the step of determining the equation of ray 5 in FIG. In step 101, the visual field information is input, and the viewpoint position, screen position, and each pixel position are known. The ray is the viewpoint position P
A straight line connecting a pixel position P _S on _V and the screen, if P _V, the position vector of P _S P _V, and P _S, t as the parameter, expressed as t (P _S -P _V) be able to. The position of P _V is fixed, but the position of P _S takes m × n positions on the screen. In this way, m
Xn ray equations can be determined.

Step 106 indicates that steps 107 to 108 are repeated for each omitted model created in step 103. FIG.
As shown in FIG. 5, there are usually a plurality of generated omission models. For example, in addition to omission model 4, omission model A and omission model B exist. In this step, all the abbreviated models are detected from the tree structure of FIG. 7 for the one ray 5 determined in steps 104 and 105, and the iterative process of steps 107 and 108 is performed.

Step 107 is means for determining whether the ray 5 has an intersection with each omitted model. The ray equation is the straight line equation determined in step 105, and the abbreviated model is described by the six plane equations as in FIG. Therefore, the determination of the intersection can be obtained as the intersection problem between the straight line and the plane. If the ray being processed passes through the inner area of the six planes of the omitted model, it is determined that there is an intersection.

Step 108 is a step of displaying an abbreviated model when an intersection is detected in step 107. The detection of the intersection point means that the light beam being processed is also projected on the screen 2 as an image of the abbreviated model. Therefore, the abbreviated model is displayed on one pixel on the screen through which the light ray passes. However, when there are a plurality of intersections, the intersection closest to the viewpoint is displayed. Step 10 for all pixels on screen
At the time when the process up to 8 is completed, all the omitted models are projected and drawn on the screen 2 as shown in FIG.

Step 109 is a step for detecting the omitted model drawn on the screen in the above steps and repeating steps 110 to 113. As shown in FIG. 9, the screen has data as an m × n two-dimensional array, and the array data is searched to detect the omitted model.

Step 110 is a step of judging the size of the omitted model projected / drawn on the two-dimensional screen. For example, as shown in FIG. 9, it is assumed that two omitted models have been projected and drawn. To determine the size, for example, the size (u ₁ , v ₁ ) projected in the horizontal (u) direction and the vertical (v) direction of the flat screen is used as a reference. It is determined whether or not the values of u ₁ and v ₁ exceed the minimum size required for displaying the detailed model input in step 101.

In step 111, the model data is switched to the detailed model for the omitted model determined to be displayed in the detailed model based on the size projected on the screen in step 110, and steps 112 and 113 for each detailed model. Is a step for repeatedly processing. The detailed model is usually composed of a large number of graphic elements as shown in FIG. 3, and the steps up to step 113 are repeated for all these graphic elements.

Step 112 is a means for determining the intersection of the graphic element of the detailed model, and in the same manner as in step 107, the intersection of the ray equation passing through each pixel on the screen and the graphic element is determined.

Step 113 is a means for displaying a detailed model for the pixel at the position P _S where the ray determined to have an intersection in step 112 crosses the screen in the same manner as in step 108.

As described above, in the present embodiment, an abbreviated model in which the number of parameters or the number of dimensions is reduced by an algorithm is generated from the input detailed model, and the abbreviated model in which the intersection point is easily determined is first displayed, and the screen is further displayed. The detailed model is displayed only for those that are projected on the top and require detailed information. Therefore, it is possible to speed up the display process as compared with the case where all of them are displayed in the detailed model, and the omitted model is automatically generated, so that it is not necessary to input it manually.

In the above embodiment, the detailed model is displayed for a large object when it is projected on the screen. However, the processing may be terminated when the omitted model is displayed, and the detailed model may not be displayed at all. For this purpose, the process may be ended at the stage when step 108 in FIG. 2 is ended. If all the objects are displayed in the abbreviated model, the display processing time can be shortened, so that it can be used for checking the outline of the object.

Further, the determination of switching from the abbreviated model to the detailed model can be made by the operator's determination, instead of the algorithm as described above. This can be realized by replacing the means of step 110 in FIG. 2 with an interactive process with the operator. This interactive process is such that the abbreviated model drawn on the flat screen as shown in FIG. 9 is displayed on the display as it is, and the operator visually observes the display and switches to the detailed model display by a pointing device such as a stylus pen. To indicate the model. In this way, by instructing the switching to the detailed model through the interactive processing, the omitted model can be left according to the intention of the operator, so that the intentionally omitted display can be performed.

As a method of switching to the detailed model, it is possible to switch based on the distance from the viewpoint to the omitted model. A flowchart in this case is shown in FIG. First, in step 101, in addition to the detailed model and the visual field information, a switch setting value based on the viewpoint-intersection distance is input. Since the subsequent steps 102 to 107 are the same as those described above, description thereof will be omitted. In step 201, the distance between the viewpoint and the intersection is calculated based on the position of the intersection of the omitted model and the ray obtained in step 107. As shown in FIG.
The point of view P _V and the point of intersection P ₀ on the abbreviated model are two points on the ray 5, and the distance between these two points can be easily obtained. Step 202 is the above-mentioned viewpoint-intersection distance, and step 10
The set value input by 1 is compared in magnitude. If the calculated distance is larger than the set value, that is, if it is far, the abbreviated model is displayed in the pixel at the position of P _S (FIG. 8) on the screen in step 203. On the other hand, if it is smaller than the set value, that is, if it is close, step 11 in FIG.
Similar to steps 1 to 113, the detailed model is displayed on the pixel at the position P _S in steps 204 to 206. In this way, when switching from the abbreviated model to the detailed model according to the distance from the viewpoint, all the models are not displayed once as the abbreviated models and then sequentially switched to the detailed model. The detailed model is separated from the detailed model, and the display man-hours of the omitted model are small, so that the processing speed can be increased.

It is possible to switch between the abbreviated model and the detailed model depending on the size of the object model itself.
FIG. 11 is a flowchart showing this method. First, in step 101, which is an input step, in addition to the detailed model and the visual field information, a set value for generating an abbreviated model depending on the size of the model is input. Step 102 is shown in FIG.
Is the same as Step 301 is means for determining the size of the detailed model as shown in FIG. 5, which is projected in each of the XYZ axis directions to obtain the size of the model. Then, if it is smaller than the set value input in step 101, the omitted model is generated in step 302. Further, in step 302, as shown in FIG. 12, when an abbreviated model is generated for each object or part, it is replaced with a detailed model. That is, either one of the detailed model and the omitted model is assigned to the part or the object. Steps 104 and 105 are the same as in FIG. Step 30
3 detects a model corresponding to an object or a part on the data structure of FIG. 12, and repeats steps 304 to 308. In step 304, it is determined whether the assigned model is a detailed model or an abbreviated model. If the model is a detailed model, display processing is performed in steps 305 and 306, and if it is an omitted model, display processing is performed in steps 307 and 308. To do. In this way, when switching to the abbreviated model depending on the size of the object model, the abbreviated model is assigned only by the shape information of the model, and thus the abbreviated display is performed independently of the viewpoint position. be able to. In other words, regardless of the viewpoint position, only a small object can be displayed as an abbreviated model.

In computer graphics, a moving image is displayed by continuously displaying still images created frame by frame at about 30 frames / sec. At the time of displaying this moving image, only the object moving on the screen can be switched to the abbreviated model and displayed. FIG. 13 is an example showing the contents of the model information of the graphic element (cylinder) shown in FIGS. 3 and 4. In the figure, 2h is the length of the cylinder, 2r is the diameter of the cylinder, and these are called primitive information. The center P is a _x indicates a position from the origin O on the cylinder, a _y, a a _z, rotation angle theta _x indicating the direction of the cylinder, theta _y, a theta _z, and these arrangement information Call. When an object moves on the display, that is, the screen, firstly, the arrangement information is changing between frames, and secondly, the visual field information is changing. Here, a method of displaying the abbreviated model when an object is moving on the screen will be described with reference to FIG. Step 401 is a step of inputting the detailed model / field-of-view information and the like one frame before the frame currently being processed. In step 101, the detailed model / field-of-view information of the current frame is input. Step 102 is similar to the example of FIG. Step 402 is the step of determining the behavior of the model,
Changes in the arrangement information and the visual field information are detected from the information input in steps 401 and 101. If it is determined that there is an operation, the detailed model is replaced with the omitted model in step 302 as shown in FIG. The following steps are similar to the example of FIG. 11, and it is possible to display only the moving object by the abbreviated model. In the case of displaying a moving image, it is difficult to gaze at a moving object on the display, and detailed information of the model cannot be recognized. Therefore, if the speed of the moving object is omitted and displayed as the evaluation index, there is an effect that the deterioration of the image quality is small and the processing speed is increased.

In the above embodiments, the detailed model and the abbreviated model are switched instantaneously with a certain frame as a boundary. However, the transmittance of the model is defined, and this is gradually changed as the third model. It is possible to switch while doing. For example, in FIG. 1, it is assumed that the display image in the first frame is the display 6 based on the detailed model. This object starts to move from the second frame, and the display is switched to the abbreviated model display, but the switching is completely completed in the fourth frame. Between the 1st to 4th frames, as shown in FIG. 15A, the transmittance of the detailed model is 0.
%, 33%, 66%, 100%, while the omitted model changes to 100%, 66%, 33%, 0%. In short, the detailed model is displayed so as to become lighter, and the omitted model is displayed as it becomes darker. Here, the transmittance is a number indicating the rate at which light rays pass through an object,
The transmittance is 0% when the object is completely visible, and 100% is when the object is not completely visible. FIG. 15B is a flowchart showing this method. Steps 401 and 101
Is similar to the case of FIG. Step 501 is a step of inputting the transmittance information of the object that has already started the operation, and the transmittance of the detailed and omitted models in the current frame is input. Step 102 to Step 303
Up to this is the same as in the case of FIG. Steps 502 and thereafter are means for determining and displaying the intersection of the ray and the model. First, in step 502, the presence or absence of the omitted model is detected. For example, like the component 1 in FIG. 7, detection is performed for one object or component for which an abbreviated model is assigned in addition to the detailed model. For objects to which the omitted model is not assigned, the detailed model is normally displayed in step 503. On the other hand, if the omitted model is assigned, the detailed model is transparently displayed in step 504, and then the omitted model is transparently displayed in step 505. Overwriting means that the color of one pixel is mixed and displayed according to the ratio of the transmittance of both. For example, the transmittance of the detailed model is A, the display color of the detailed model is C _1, and the transmittance of the omitted model is (1-
A), assuming that the display color is C ₂ , the transparent display color C is calculated and obtained as C = A · C ₁ + (1-A) C ₂ . In this way, by switching from the detailed model to the abbreviated model while changing the transmittance, it is possible to switch while the both overlap, so that a smooth moving image display is possible.

As a stepwise switching method from the detailed model to the abbreviated model, the detailed model can be gradually deformed and displayed while matching the abbreviated model. For example, as shown in FIG. 16, it is assumed that the detailed model has a cylindrical shape and the omitted model has a rectangular parallelepiped shape. here,
Corresponding points are determined on each model for sequentially transforming from a cylinder to a rectangular parallelepiped. For example, as shown in the figure, P _{1 to} P ₁₆ for the detailed model and P ′ for the omitted model.
Defining a ₁ to P _'16, and corresponding points. FIG. 17 is a top view of FIG. 16, and is a diagram illustrating a method of generating an interpolation model in the middle of deformation from a detailed model and an omitted model. Now, assuming that the generated interpolation model is exactly in the middle of the detailed model and the omitted model, the corresponding points Q ₁ to
To find Q ₈ , the midpoints from the line segment P ₁ P ′ ₁ to the line segment P ₈ P ′ ₈ may be sequentially obtained. A flow chart of this method is shown in FIG. Steps 401 and 101 are shown in FIG.
Is the same as in the example. Step 601 is a step of inputting corresponding point information, and when a detailed model and an abbreviated model exist as shown in FIG. 16, each corresponding point is determined. Steps 102 to 503 are the same as in the example of FIG. Step 602 is a step of generating an interpolation model having a shape between the detailed model and the omitted model, which is generated as shown in FIG. And step 603
At, the generated interpolation model is displayed. By switching from the detailed model to the abbreviated model while sequentially deforming in this way, it is possible to prevent momentary switching, and thus it is possible to perform smooth moving image display.

Instead of generating an abbreviated model from the detailed model, a three-dimensional abbreviated model is first defined as shape data, and the transmittance data describing the transparency of the object to the light rays is mapped in a two-dimensional table format. It is also possible to define and display a detailed model by means of storing and pasting mapping data to the shape model. As shown in FIG. 19, an abbreviated model is defined as three-dimensional shape data. For example, in the example of the figure, the coordinate values of four vertices P ₁ to P ₄ of the abbreviated model _{(x 1, y 1, z} 1) ~ (x 4,
y ₄ and z ₄ ) are defined. The transmittance data is two-dimensional data having a distribution as shown in the figure. For example, the transmittance is 100% in the shaded area and 0% in the areas other than the shaded area. Here, in order to attach the transmittance data to the omitted model by the mapping means, it is necessary to determine the correspondence between the omitted model and the transmittance data. For example, in this embodiment,
M ₁ ~M ₄ 4 corner points of the transmittance data shall correspond to four vertices P ₁ to P ₄ of the optional model. The correspondence between points other than the vertices is interpolated at the position from the vertices. FIG. 20 is a flow chart for explaining this embodiment. In step 101, a detailed model and visual field information are input. In this step, the detailed model information includes the omitted model, the transmittance data, and the correspondence relationship between the two, and all of these are input. In this embodiment, the detailed model and the omitted model are switched based on the distance from the viewpoint. However, as described above, there are several methods for switching between the detailed model and the omitted model, and any switching method can be combined in this embodiment. Step 104
The subsequent steps are almost the same as those in FIG.
The iterative process for the detailed model after 4 is shown in FIG.
As shown in, the processing is performed for each of the omitted model and the transmittance data. In the intersection determination means of step 205, when the intersection is in the portion where the transmittance is 100%, the light ray passes through the model, and therefore it is processed as if there is no intersection. On the other hand, if the intersection is in the portion where the transmittance is 0%, it is processed as if there is the intersection. By these processes, as shown in FIG. 21, it is possible to obtain a display by the detailed model and a display by the abbreviated model on the display. In this way, by mapping the transmittance data to the abbreviated model and defining the detailed model, light rays are transmitted at the 100% transmittance portion, so the object is not displayed apparently, so the outline of a complicated object is not displayed. A line can be expressed only by the transmittance distribution, and a complicated object can be described with a small amount of shape data. Further, it is possible to switch between the detailed model and the omitted model by using / not using the transmittance data, and it is possible to speed up the process by omitting and displaying the less important objects.

The detailed model can also be displayed by mapping the transmittance data and the color data on the omitted model. Color data shown in FIG. 22 is further added to the omitted model and the transmittance data shown in FIG. This color data has a two-dimensional table format like the transmittance data, and similarly defines corresponding points M ′ _{1 to} M ′ ₄ with the omitted model. Then, by performing the same processing as in FIG. 20, it is possible to obtain a display by the detailed model or a display by the omitted model on the display 8 as shown in FIG. By further adding color data in this way, a complicated pattern of an object can be registered as two-dimensional data, so that a more detailed detailed model display can be obtained.

The detailed model display can be obtained by adding the transmittance data, the color data, and the normal line data to the omitted model. FIG. 24 is a diagram showing the concept of additional normal data, in which the distribution of normal vectors on the object is stored in a two-dimensional table format. Similar to the transmittance data and the color data, corresponding points M ′ _{1 to} M ′ ₄ are determined and the corresponding relationship with the omitted model is determined. When calculating the inner product of the light source vector and the normal vector to determine the display color, the normal line data on the table is used as it is, instead of calculating the normal line of the object. Then, as shown in FIG. 24, the actually stored normal data is as shown in (b), and the shape of the omitted model is a plane, but if the display is determined by the inner product calculation with the light source vector, It appears to have a surface like. FIG. 25 is an example in which transmittance data, color data, and normal line data are added to the omitted model and displayed as a detailed model. The display example using the abbreviated model is the same as in the case of FIG. 21. Since the normal data is in a two-dimensional table format and the distribution of various normals can be defined, an object with complicated surface irregularities is displayed as a detailed model. can do.

It is also possible to obtain the detailed model display by giving transmittance data, color data, normal line data, and vertex normal line data to the omitted model. FIG. 26 shows the vertex normal vector N ₁
The to N _4, an example given four vertices P ₁ to P _4, by specifying the direction extending outwardly, it is an example of displaying by shading as this plane and curved surface. FIG. 27 is a diagram showing the reason why a curved surface is displayed. Now, as shown in (a), N ₄ is calculated from the interpolation of the vectors of N ₁ and N ₄ , and similarly N ₂
Calculating the N _A 'from N ₃ and. Then, the vector is further interpolated from N _A and N _A ′ to obtain the normal vector in the omitted model. As a result (b), all normals on the omitted model are obtained by interpolation. If this normal vector is used for the inner product calculation with the light source vector, the display brightness will change smoothly on the display and the display will look like a curved surface. Further, when the normal line resulting from this interpolation and the ray data on the two-dimensional table shown in FIG. 24B are vector-added and displayed, even if the shape data is flat as shown in FIG. It is possible to display a more uneven object as a detailed model.

In addition to the above, optical characteristics such as a reflection coefficient can be input as the value to be stored as the mapping data. As a result, it is possible to display an object whose optical characteristics are changed on the surface.

Instead of adding the transmittance data, the color data, and the normal line data to a single omitted model, these data can be added to an omitted model having a plurality of graphic elements. In the example shown in FIG. 28, the abbreviated model is a collection of 6 plane elements, and has ₁₂ vertices P _{1 to} P ₁₂ . In the case of such an abbreviated model, the corresponding points corresponding to the respective vertices may be defined in the data in the two-dimensional table format, and in the case of the figure, M _{1 to} M ₁₂ , M ′ _{1 to} M ′. ₁₂ , M ″ ₁
~ M ″ ₁₂ is designated. In this way, the display of the abbreviated model and the detailed model can be realized by the flow chart as shown in FIG. As shown, a detailed model representation and an abbreviated model representation can be obtained on the display.

When an abbreviated model is generated from the detailed model and displayed, one abbreviated model may not be assigned to the same object, but a plurality of abbreviated models having different degrees of detail may be assigned and displayed. In the example shown in FIG. 30, n omitted models and detailed models are assigned to the component 1. Here, an abbreviated model is generated by reducing the number of parameters or the number of dimensions from the detailed model, and the one with the smallest number of parameters or dimensions is called the first abbreviated model,
Hereinafter, the second, ..., Nth omitted model will be referred to. FIG.
1 is a flowchart showing a method of allocating and displaying abbreviated models having different levels of detail. First, step 701
Then, in addition to the detailed model and the visual field information, the switching set value is input. This is a value for designating an abbreviated model to be displayed, and when switching is performed according to the distance from the viewpoint as in the present embodiment, n distance values from set values 1 to n are designated. These switching set values are set in the order of increasing distance from the viewpoint 1,
Set value 2, ... Set value n. Steps 104 and 1
05 is similar to the example of FIG. Step 702 means repeating the following steps for the first omitted model having the smallest number of parameters or dimensions. Steps 702 and 107 are similar to the example of FIG. Step 703 is a step of comparing the viewpoint-intersection point distance obtained in step 201 with the switching set value input in step 701. An object located at a distance farther than the set value 1 farthest from the viewpoint is displayed in step 704 using the first abbreviated model. If the object is at a distance between the set value 1 and the set value 2, the step 7
At 05, the intersection of the second omitted model and the ray is checked, and if there is an intersection, this is displayed. For an object closer to the set value n, the intersection with the ray is checked in step 705, and if there is an intersection, a detailed model is displayed. Now, assuming that n = 2, the second omitted model is a circumscribed rectangular parallelepiped of the detailed model generated as shown in FIGS. 5 and 6. Then, the first omitted model can be generated from the second omitted model. That is, as shown in FIG. 32, a circumscribing sphere having a radius r with the point C as the center is generated and used as the first omitted model. At this time, the point C is the center of gravity of the circumscribed rectangular parallelepiped, and the radius r is 1/2 the length of the diagonal line of the circumscribed rectangular parallelepiped. The circumscribed sphere is described by one quadratic equation, and the number of parameters is smaller than that of the circumscribed rectangular parallelepiped described by six plane equations. In this way, by assigning and displaying an abbreviated model having a smaller number of parameters or dimensions than a certain abbreviated model, it is possible to further simplify the display of less important objects, which is effective in shortening the display time. .

As a method of generating the first to n-th omitted models from the detailed model, it is possible to change the number of divisions of the figure. In the example shown in FIG. 33, the detailed model has a cylindrical shape, and this is divided into straight lines in the circumferential direction and
The second omitted model is a prism. Then, the number of divisions of the second omitted model is reduced to form an octagonal prism as the first omitted model. Since the first omitted model has a smaller number of planes than the second omitted model and is described with a small number of parameters, it is possible to speed up the display time by assigning this to an object of low importance. The number of divisions can be automatically set by evaluation functions such as distance and size, and it is not necessary to save the abbreviated model as data in advance, and data can be compacted.

A complete two-dimensional figure can be used as a method of reducing the number of dimensions and calculating and allocating an omission model having a lower degree of detail. For example, as shown in FIG. 34, a circumscribing figure is obtained with the three-dimensional second omission model projected on the screen, and this is assigned as the first omission model. By allocating the two-dimensional figure in this way, the display process becomes extremely simple, and the display time can be shortened.

In the above example, the abbreviated model is automatically generated from the detailed model by an algorithm. However, when the abbreviated model is defined across parts, the operator gives an instruction in advance. It can also be displayed. FIG. 35 is a diagram showing a method of defining an abbreviated model instructed by an operator. For example, in FIG.
As shown in (a), the object 1, the part 1, the part 2, and the part 3 are ORed.
It is defined by the combination (denoted by U), and the detailed model has a shape in which three cylinders are overlapped as shown in the figure. The state expressed in the detailed model in this way is described as follows: object 1 = part 1U part 2U part 3. Next, when only the component 1 is switched to the omitted model as shown in FIG. 5B, the component to be switched to the omitted model is enclosed in parentheses () so that the object 1 = (component 1) U component 2U component 3 To do. Similarly, as shown in FIG.
In the case where the parts and the parts 2 are omitted models, object 1 = (part 1U parts 2) U parts 3 and in the case where all the parts are omitted models as shown in FIG. 35 (d), object 1 = ( Parts 1U parts 2U parts 3) are defined and the omitted models are assigned. In the present embodiment, it is possible to assign an abbreviated model according to an operator's instruction, and the texture is finer than in the case of automatic generation, and control for abbreviated model assignment is possible.

According to the embodiment of the present invention, a less important object can be automatically identified on the screen, and an abbreviated model in which the number of parameters or the number of dimensions is subtracted from the detailed model can be automatically generated and displayed. Therefore, it is effective in increasing the display speed. For example, when finding the intersection of a line of sight with a three-dimensional model, it is treated as a problem of finding the intersection of the function that describes the model and the viewpoint that is a straight line, but the intersection of a higher-order function and a straight line is easily found. It takes a lot of processing time.
However, if a model in which the number of dimensions is reduced to first order or two dimensions is used as an abbreviated model, the intersection of this model and the line of sight can be obtained very easily.

The determination of switching to the abbreviated model and the generation of the model are all performed automatically, and there is no need for operator intervention. For example, if you define one detailed model and one omitted model for all objects,
If there is no automatic generation function of the abbreviated model, the operator needs to input twice as many models as the object, but in the embodiment of the present invention, only the detailed model needs to be input, which reduces the input man-hour. Is also effective.

[0051]

According to the present invention, a natural image can be displayed in computer graphics at high speed.

[Brief description of drawings]

FIG. 1 is a schematic diagram and a hardware configuration diagram of an embodiment of the present invention.

FIG. 2 is a flowchart for realizing by a computer algorithm.

FIG. 3 is an explanatory diagram of graphic elements forming a detailed model.

FIG. 4 is a tree structure diagram showing the configuration of graphic elements.

FIG. 5 is an explanatory diagram of a method of obtaining an abbreviated model from a detailed model.

FIG. 6 is an explanatory diagram of a plane forming an abbreviated model.

FIG. 7 is a tree structure diagram showing a configuration of an omitted model after allocation.

FIG. 8 is an explanatory diagram of a method of projecting an abbreviated model on a screen.

FIG. 9 is an explanatory diagram of an abbreviated model projected on a screen.

FIG. 10 is a flowchart when models are switched according to the viewpoint-intersection distance.

FIG. 11 is a flowchart in the case of performing model switching according to the size of the omitted model.

FIG. 12 is a tree structure diagram showing allocation of models in the case of FIG.

FIG. 13 is an explanatory diagram of model information of graphic elements.

FIG. 14 is a flowchart in the case of performing model switching for a moving object.

15A and 15B are an explanatory diagram and a flow chart when a model is switched while changing the transmittance.

FIG. 16 is an explanatory diagram of corresponding points between the detailed model and the omitted model.

17 is an explanatory diagram of a method of generating an interpolation model in the top view of FIG.

FIG. 18 is a flowchart of a case where a detailed model is deformed and an abbreviated model is switched.

FIG. 19 is an explanatory diagram of an abbreviated model and transmittance data.

FIG. 20 is a flow chart of a method for providing detailed model display by adding transmittance data to an abbreviated model by mapping.

FIG. 21 is an explanatory diagram of the display of a detailed model and an abbreviated model obtained from the display by the method of FIG. 20.

FIG. 22 is an explanatory diagram of color data added by mapping of an abbreviated model.

FIG. 23 is an explanatory diagram of a display by a detailed model and an abbreviated model on the display when the color data of FIG. 22 is added to the data of FIG.

FIG. 24 is an explanatory diagram of normal line data added to the omitted model.

FIG. 25 is an explanatory diagram of a display by a detailed model on the display when the normal line data of FIG. 24 is added to the data of FIGS. 19 and 22.

FIG. 26 is an explanatory diagram of vertex normals given to the omitted model.

FIG. 27 is an explanatory diagram of an interpolation method of vertex normals.

FIG. 28 is an explanatory diagram of a case where the omitted model is composed of a plurality of graphic elements.

FIG. 29 is an explanatory diagram of a detailed model and an abbreviated model when the data of FIG. 28 is displayed on the display.

FIG. 30 is a tree structure diagram showing a data structure when a plurality of omitted models with different degrees of detail are assigned to a single part.

31 is a flow chart of a method of displaying the data of FIG.

FIG. 32 is an explanatory diagram showing a method of generating a first omission model based on a circumscribing sphere from a second omission model based on a circumscribing cuboid.

FIG. 33 is a diagram illustrating the second method by controlling the number of divisions of the figure from the detailed model.
It is explanatory drawing which shows the method of generating an abbreviated model and a 1st abbreviated model.

FIG. 34 is an explanatory diagram of a method of generating a first omitted model by subtracting the number of dimensions from the second omitted model.

FIG. 35 is an explanatory diagram showing a description method when assigning models with different degrees of detail according to operator instructions.

[Explanation of symbols]

1 ... Viewpoint, 2 ... Screen, 3 ... Detailed model, 4 ... Omitted model, 5 ... Ray, 6 ... Detailed model display, 7 ... Omitted model display, 8 ... Display screen.

Claims (3)

[Claims] 1. A computer graphics display method for storing a three-dimensional detailed model of an object and its three-dimensional omitted model, and switching between the detailed model and the omitted model for display on a display device. Judge the size on the screen,
When the size is larger than a preset value, the detailed model is displayed, and when the size is smaller than the preset value, the abbreviated model is displayed to display on the display device. A computer graphics display method characterized by performing. 2. A computer graphics display method for storing a three-dimensional detailed model of an object and its three-dimensional omitted model, and switching between the detailed model and the omitted model for display on a display device. A computer graphics display method, characterized in that the detailed model and the omitted model are switched according to the moving speed to perform display on a display device. 3. A computer graphics display method for storing a three-dimensional detailed model of an object and its three-dimensional omitted model, and switching between the detailed model and the omitted model for displaying on a display device. A computer graphics display method, characterized in that, when switching between a model and a display device for display, switching is performed while changing the respective transmittances of the detailed model and the omitted model.