Computation system and method for generating 3D CG model

Abstract

This computation system comprises: a component identification unit that identifies, on the basis of a condition, a component to be deleted from a 3D CAD model; a captured image generation unit that uses the 3D CAD model to generate a CAD captured image that is a rendering image including the component to be deleted; a component deletion unit that deletes, from the 3D CAD model, the component to be deleted determined by the component identification unit, thereby generating a deletion-completed CAD model; a converter that converts the deletion-completed CAD model into a 3D CG model; and an image pasting unit that pastes an image based on the CAD captured image to the 3D CG model.

Description

Calculation system, method for generating a 3D CG model

[0001] The present invention relates to a calculation system and a method for generating a 3D CG model.

[0002] By using the 3D data of an object, the object can be observed from various angles within a screen or in a virtual space, and the utilization of 3D data is expanding. In Patent Document 1, there is a device that performs a process of deleting data that becomes unnecessary as long as it is used under a certain condition by determining a viewpoint arrangement condition for the 3D shape data of an object. The 3D shape data of the object to be processed is input as pre-process data and stored in a pre-process data storage means. An enclosure data setting means sets enclosure data which is the 3D shape data of an enclosure surrounding the periphery of the object. A light source is set at a position outside the object and inside the enclosure, and an illumination simulation is performed considering that the energy of the illumination light emitted from this light source is repeatedly reflected by each part of the object and the enclosure, and a luminance calculation means calculates the luminance of each part of the object. Data deletion means deletes data related to parts where the luminance obtained by the luminance calculation means is below a predetermined threshold value from the pre-process data, and outputs the remaining data as post-process data. An apparatus for reducing 3D shape data of an object is disclosed, which is characterized by comprising these components.

[0003] Japanese Patent Application Laid-Open No. 2007-26036

[0004] In the invention described in Patent Document 1, the viewpoints from which the 3D shape data can be viewed are limited.

[0005] A calculation system according to a first aspect of the present invention includes: a part identification unit that identifies a part to be deleted from a 3D CAD model based on conditions; a captured image generation unit that generates a CAD captured image, which is a rendering image including the part to be deleted, using the 3D CAD model; a part deletion unit that deletes the part to be deleted determined by the part identification unit from the 3D CAD model to generate a deleted CAD model; a converter that converts the deleted CAD model into a 3D CG model; and an image pasting unit that pastes an image based on the CAD captured image onto the 3D CG model. A method for generating a 3D CG model according to a second aspect of the present invention is a method for generating a 3D CG model executed by a computer, comprising: identifying a part to be deleted, which is a part to be deleted from a 3D CAD model based on conditions; generating a CAD image, which is a rendering image including the part to be deleted, using the 3D CAD model; deleting the determined part to be deleted from the 3D CAD model to generate a deleted CAD model; converting the deleted CAD model into a 3D CG model; and pasting an image based on the CAD image onto the 3D CG model.

[0006] According to the present invention, it is possible to generate three-dimensional shape data that can be viewed from any viewpoint without being limited to a specific viewpoint.

[0007] Functional configuration diagram of the computing device Hardware configuration diagram of the computing device Flowchart showing the processing of the computing device Diagram showing the use case selection screen Diagram showing the deletion target attribute selection screen Diagram showing a comparison of a 3D CAD model and a 3D CG model Diagram showing an example of selecting the display target viewpoint in modified example 2 Diagram showing an example of deleting a part in modified example 2

[0008] —First Embodiment— Hereinafter, embodiments of the calculation system and the method for generating a 3D CG model will be described with reference to Figures 1 to 6.

[0009] Figure 1 is a functional configuration diagram of the arithmetic unit 1. In this embodiment, the person using the arithmetic unit 1 is referred to as the "user". The arithmetic unit 1 includes a CAD program 11, a 3D CG program 12, a converter 13, a component identification program 14, an image search program 15, and an image pasting program 16. The arithmetic unit 1 also stores a CAD model database 41, a 3D CG model database 42, a photo database 43, a CAD captured image database 44, and an application table 45. Before describing the functional configuration, the hardware configuration will be described.

[0010] Figure 2 is a hardware configuration diagram of the arithmetic unit 1. The arithmetic unit 1 comprises a CPU 51 which is a central processing unit, a ROM 52 which is a read-only storage device, a RAM 53 which is a read-write storage device, a storage 54 which is a non-volatile storage device, an input / output device 55 which is a user interface, and a communication device 56. The aforementioned CAD model database 41, 3D CG model database 42, photo database 43, CAD captured image database 44, and usage table 45 are stored in the storage 54. However, various databases may be loaded into the RAM 53 from outside the arithmetic unit 1.

[0011] The CPU 51 performs the various calculations described above by loading the program stored in the ROM 52 into the RAM 53 and executing it. The arithmetic unit 1 may be implemented using a rewritable logic circuit such as an FPGA (Field Programmable Gate Array) or an application-specific integrated circuit such as an ASIC (Application Specific Integrated Circuit) instead of the combination of CPU 51, ROM 52, and RAM 53. Alternatively, the arithmetic unit 1 may be implemented using a different configuration, such as a combination of CPU 51, ROM 52, RAM 53 and FPGA, instead of the combination of CPU 51, ROM 52, and RAM 53.

[0012] Although Figure 2 shows the arithmetic unit 1 as being composed of a single hardware device for convenience, the arithmetic unit 1 may be composed of multiple hardware devices. In this case, the hardware devices may be installed adjacent to each other, or they may be connected via a local area network or the internet. Since the functions of the arithmetic unit 1 may be realized by multiple devices, the arithmetic unit 1 can also be called an "arithmetic system".

[0013] Storage 54 is a non-volatile storage device that stores the aforementioned database and the like. However, the program may be stored in storage 54 instead of ROM 52, or a part of the database may be stored in ROM 52. Input / output devices 55 exchange data with the user directly or indirectly. For example, input / output devices 55 are a mouse, keyboard, and display that exchange data directly with the user. Alternatively, for example, input / output devices 55 may be a physical interface that can connect to the mouse, keyboard, and display, and exchange data indirectly with the user.

[0014] The communication device 56 enables communication between the arithmetic unit 1 and other devices. The arithmetic unit 1 can receive programs and data from other devices via the communication device 56. The communication device 56 may also function as an input / output device 55 by communicating with the mouse, keyboard, and display. Let's return to Figure 1 and continue the explanation.

[0015] The CAD model database 41 stores one or more 3D CAD models. A single 3D CAD model contains multiple parts. Each part has detailed shapes and attributes pre-configured. Attributes include manufacturer, type, shape, and hierarchy. The manufacturer is the creator of the part and can also be called the manufacturer, manufacturing company, or supplier. The type is the category of the part, such as screw, door, window, etc. The shape is the shape of the part, such as rectangular prism, linear, circular, etc. The hierarchy indicates the correlation and inclusion relationships between parts and can also be called parent-child relationships. In this embodiment, 3D CAD models are pre-stored in the CAD model database 41, but as will be described later, parts are deleted from the read 3D CAD models.

[0016] The 3D CG model database 42 stores one or more 3D CG models output by the converter 13. 3D CG models have a different data format than 3D CAD models and contain less information, resulting in a relatively smaller data size. The photo database 43 stores images obtained by photographing various real-world objects with a camera. These images can also be called photographic data or real images. In this embodiment, images are pre-stored in the photo database 43, and no additional images are added to the photo database 43 in this embodiment. The CAD image database 44 stores CAD images, which are images obtained by rendering a 3D CAD model with the CAD program 11.

[0017] Table 45 of the Usage Table is a pre-created table showing the relationship between usage and size thresholds. Size can be length, area, or volume, and can be either an absolute or relative value. For example, size can also be set as the ratio of the volume of the target part to the volume of a given 3D CAD model. This threshold is used for model deletion, as will be described later. For example, if this size threshold is set to 20%, all parts in a given 3D CAD model that are 20% or less of the total parts will be deleted. Whether to use length, area, or volume as the size, and whether to use absolute or relative values, can be arbitrarily set by the user or pre-set.

[0018] CAD program 11 is a CAD program that processes a 3D CAD model. The 3D CAD model contains multiple parts, and CAD program 11 can delete at least parts. Furthermore, CAD program 11 can render, i.e., image, the entire or a part of the 3D CAD model at any orientation or field of view. In this embodiment, the image obtained by rendering with CAD program 11 is called a "CAD captured image." As will be described later, CAD program 11 may capture the 3D CAD model based on instructions from part identification program 14, so it will also be referred to as the "captured image generation unit" below. Additionally, CAD program 11 may delete parts from the 3D CAD model based on instructions from part identification program 14, so it will also be referred to as the "part deletion unit" below. Below, the 3D CAD model from which CAD program 11 has deleted parts will also be referred to as the "deleted CAD model."

[0019] The 3D CG program 12 displays the 3D CG model output by the converter 13 on a display device described later. The 3D CG program 12 changes the position and orientation of the viewpoint, the display magnification, etc., of the 3D CG model in response to user input. The 3D CG program 12 also attaches an image to the 3D CG model based on operation commands from the image attachment program 16. The image to be attached is either a CAD-captured image or an image retrieved from the photo database 43.

[0020] Converter 13 converts a 3D CAD model into a 3D CG model. Converter 13 is, for example, a general-purpose program that performs conversions, for example, from DXF format to FBX format. However, the target of Converter 13's processing is not the data stored in the CAD model database 41 itself, but the deleted CAD model after one or more parts have been deleted by the CAD program 11. Converter 13 stores the converted 3D CG model in the 3D CG model database 42.

[0021] The part identification program 14 identifies the parts to be deleted (hereinafter referred to as "parts to be deleted") and instructs the CAD program 11 to delete the identified parts. The part identification program 14 identifies parts to be deleted using the following two methods. The first method is based on size, and the second method is based on attributes. In the first method, the part identification program 14 queries the user for the use case, i.e., the application, of the 3D CG model, and sets a size threshold based on the answer. The part identification program 14 then designates parts below that threshold as parts to be deleted. In the second method, the part identification program 14 queries the user for the attributes to be deleted, and based on the user's selection, designates parts with the corresponding attributes as parts to be deleted.

[0022] The image search program 15 searches the photo database 43 for real images similar to the CAD-captured image (hereinafter referred to as "similar real images"). The CAD-captured image used for the search is specified by the part identification program 14. The image pasting program 16 pastes the image onto the surface of the 3D CG model according to the operation commands from the part identification program 14.

[0023] Figure 3 is a flowchart showing the processing of the arithmetic unit 1. Before this flowchart is executed, the 3D CAD model to be processed is identified. This identification may be performed by the user or by someone other than the user. In step S301, the part identification program 14 displays use case options to the user using the input / output device 55. The user selects one of the options displayed on the input / output device 55 or a device connected to the input / output device 55. The user's selection is input to the arithmetic unit 1, for example, via a mouse or keyboard.

[0024] Figure 4 shows an example of the screen displayed on the input / output device 55 in step S301, and is a use case selection screen. In the example shown in Figure 4, three options are shown, and the user selects one of them. Although thresholds are listed along with the applications in Figure 4, the thresholds do not necessarily have to be displayed. The combination of applications and thresholds shown in Figure 4 is an example of data stored in the application table 45.

[0025] In the following step S302, the part identification program 14 sets a threshold value by referring to the application table 45 based on the user's selection. For example, in the example shown in Figure 4, if the user selects "Visualize", the threshold value is set to "20%". In the following step S303, the part identification program 14 displays a selection of attributes to be deleted. These attributes include, for example, manufacturer, type, shape, and hierarchy. Each part included in the 3D CAD model has attribute data, and the part identification program 14 reads the attribute data of the parts included in the 3D CAD model to be processed and displays it as a selection. The user may select one or more of the attribute selections displayed on the input / output device 55, or may not select any. The user's selection is input to the arithmetic unit 1, for example, through mouse or keyboard operation.

[0026] Figure 5 shows an example of the screen displayed on the input / output device 55 in step S303, and is a diagram showing the screen for selecting attributes to be deleted. In the example shown in Figure 5, four attributes are shown, and the user has selected one attribute value each for the manufacturer and type attributes. There is no limit to the number of attributes or attribute values ​​that the user can select; it can be zero or all can be selected. In the example shown in Figure 5, when the user selects an attribute value, a circle is displayed to indicate that it is selected, and selecting it again deselects it and removes the circle. When the user selects the deselect button 801 shown in the lower left of Figure 5, all attribute values ​​are deselected, and when the user selects the confirm button 802 shown in the lower right, the attribute values ​​that were selected at that time are confirmed as attributes to be deleted.

[0027] In the following step S304, the part identification program 14 identifies the parts to be deleted in the 3D CAD model based on the threshold set in step S302 and the user's selection of attributes displayed in step S303. For example, let's consider the case where the threshold is set to "20%" in step S302, and in step S303 the user selects the attribute value "Company B" for the "Manufacturer" attribute and the attribute value "Screw" for the "Type" attribute. In this case, the part identification program 14 identifies the parts to be deleted in the 3D CAD model being processed as parts that account for 20% or less of the total volume, parts manufactured by "Company B", and parts whose type is "Screw". However, the parts are not deleted at this point.

[0028] In the following step S305, the part identification program 14 sets the shooting range and field of view for capturing the 3D CAD model. The part identification program 14 sets the shooting range and field of view so that at least the parts to be deleted, which were identified in step S304, are captured. However, there may be multiple shooting ranges and fields of view. In the following step S306, the part identification program 14 uses the CAD program 11 to capture the 3D CAD model using a virtual camera. At this time, the part identification program 14 instructs the CAD program 11 to use the shooting range and field of view set in step S305. In the following step S307, the part identification program 14 outputs an operation command to the CAD program 11 to delete the parts to be deleted, which were identified in step S304, from the 3D CAD model.

[0029] In the following step S308, the part identification program 14 instructs the converter 13 to convert the 3D CAD model, from which the parts have been deleted by the processing in step S307, into CG format. In the following step S309, the part identification program 14 instructs the image search program 15 to search for actual images corresponding to the CAD images captured in step S306 and obtains the search results. As mentioned above, the image search program 15 searches data stored in the photo database 43.

[0030] In the following step S310, if the part identification program 14 determines that the search was successful, that is, that an actual image corresponding to the CAD image was found in the photo database 43, it proceeds to step S311. If the part identification program 14 determines that an actual image corresponding to the CAD image was not found in the photo database 43, it proceeds to step S312. In step S311, the part identification program 14 uses the actual image obtained in step S309 in the CG model and proceeds to step S313. Specifically, the part identification program 14 uses the CG model obtained in step S308 and causes the image pasting program 16 to perform the following processing. That is, the part identification program 14 pastes the actual image obtained in step S309 onto the CG model as an image showing its appearance.

[0031] In step S312, the part identification program 14 uses the CAD image captured in step S306 for the CG model and proceeds to step S313. Specifically, the part identification program 14 uses the CG model obtained in step S308 to cause the image pasting program 16 to perform the following process. That is, the part identification program 14 pastes the CAD image captured in step S306 onto the CG model as an image showing its appearance. In step S313, the part identification program 14 displays the CG model in the 3D CG program 12 and completes the process shown in Figure 3.

[0032] Figure 6 shows a comparison between a 3D CAD model and a 3D CG model. Figure 6 shows the front view of a train car with lights at the top. The upper part of Figure 6 shows the 3D CAD model, and the lower part shows the 3D CG model. As shown in Figure 6, there is almost no difference in appearance between the 3D CAD model and the 3D CG model, but some shape data has been removed, as will be explained below, to reduce the computational load for display.

[0033] As shown in the enlarged view on the right of the 3D CAD model, the light includes a light base 901, a first light 902, and a second light 903. The 3D CAD model includes not only the shape data of the light base 901 but also the shape data of the first light 902 and the second light 903. Specifically, the first light 902A and the second light 903A protrude from the light base 901, and the thickness of the light is clearly indicated. Although shown in white in this figure, the 3D CAD model also includes color or texture data for each face of the first light 902 and the second light 903.

[0034] In the example shown in Figure 6, the first light 902 and the second light 903 were selected as parts to be deleted in step S304. The reason for selection may be size or attribute. If size is the reason, it is when the length, area, or volume of the first light 902 and the second light 903 is smaller than a threshold. If attributes are the reason, it is when "light" is selected as the attribute type, or when "protrusion" is selected as the attribute shape. In this case, in step S305, the light base 901 is set to be the shooting range for each of the first light 902 and the second light 903, or both together, as the area containing the parts to be deleted.

[0035] In the 3D CG model shown at the bottom of Figure 6, the light base 901A, the first light 902A, and the second light 903A are also shown. However, the first light 902A and the second light 903A do not have shape data and are represented as images pasted onto the light base 901A. Therefore, although the thickness was represented in the 3D CAD model shown at the top, the thickness is omitted in the first light 902A and the second light 903A of the 3D CG model. Although there are differences when observing the details in this way, the 3D CG model generated by this embodiment can reduce the amount of data by deleting the data of parts that meet the conditions, thereby reducing the computational load when displaying it. In the example shown in Figure 6, it is preferable that the image pasted onto the light base 901A be an actual image if possible (S311), and if an actual image is not available, an image of the 3D CAD model before deleting the first light 902 and the second light 903 is used (S312).

[0036] According to the first embodiment described above, the following effects can be obtained. (1) The arithmetic device 1, which can also be called an arithmetic system, includes: a part identification program 14 that identifies parts to be deleted from a 3D CAD model based on conditions; a CAD program 11, which can also be called a captured image generation unit, that generates a CAD captured image, which is a rendering image including the parts to be deleted, using the 3D CAD model; a CAD program 11, which can also be called a part deletion unit, that deletes the parts to be deleted determined by the part identification program 14 from the 3D CAD model to generate a deleted CAD model; a converter 13 that converts the deleted CAD model into a 3D CG model; and an image pasting program 16 that pastes an image based on the CAD captured image onto the 3D CG model. As a result, the arithmetic device 1 can generate 3D shape data that can be viewed from any viewpoint without limiting the viewpoint.

[0037] (2) The computing device 1 includes an image search program 15 that searches for similar real-world images that are similar to the CAD-captured images, using images obtained by photographing real-world objects as the target. The image pasting program 16 pastes the similar real-world image onto the 3D CG model if the image search program 15 can obtain a similar real-world image (S310: YES, S311 in Figure 3), and pastes the CAD-captured image onto the 3D CG model if the image search program 15 cannot obtain a similar real-world image (S310: NO, S312). Therefore, by using real-world images when available, a more realistic 3D CG model can be generated.

[0038] (3) The conditions for identifying parts to be deleted are that the size of the part is below a predetermined threshold (S301, S302 in Figure 3), where size refers to length, area, or volume. Since small parts have a relatively small impact on the overall appearance of the model, deleting parts below the threshold from the 3D CAD model can reduce the amount of data in the 3D CG model while minimizing the impact on the appearance.

[0039] (4) The predetermined threshold is determined based on the use case of the 3D CG model selected by the user, after referring to the application table 45. Therefore, a 3D CG model can be created that is suitable for the application. For example, if the purpose is to check the general shape, a high threshold can be set to create a 3D CG model with a large number of parts removed.

[0040] (5) The conditions for identifying the parts to be deleted are determined by the attributes of the parts. The attributes include at least one of the manufacturer, type, shape, and hierarchy. Therefore, the computing unit 1 can generate a 3D CG model from which parts having the attributes selected by the user have been deleted.

[0041] (Modification 1) In the embodiment described above, the parts to be deleted were identified based on both size (S302) and attributes (S303). However, the parts to be deleted may be identified based on size only, or based on attributes only.

[0042] (Modification 2) In the embodiment described above, the attributes (S303) for identifying the parts to be deleted were manufacturer, type, shape, and hierarchy. However, the attributes may be at least one of these four, or any other attribute that can identify the parts, such as the display viewpoint. In this case, parts that are not displayed from the display viewpoint will be deleted.

[0043] Figures 7 and 8 illustrate an example of part deletion based on the display target viewpoint. Figure 7 illustrates an example of selecting the display target viewpoint. In this example, the right side is selected as the display target viewpoint. In this case, parts that are displayed in the right side viewpoint are not deleted, and parts that are not displayed in the right side viewpoint are targeted for deletion. Specifically, the right door 911 and right window 912, which are displayed in the right side viewpoint, are not deleted. However, the left door 913 and left window 914, which are not displayed in the right side viewpoint, are deleted. However, the wheels and body are not deleted as they are also included in the right side viewpoint, and the body and wheels remain in the left side viewpoint as well.

[0044] According to the second modification example, in addition to the operational effects in the first embodiment, the following operational effects are achieved. (6) The attribute is the viewpoint, and the component identification program 14 identifies components that are not displayed from the viewpoint selected by the user as components to be deleted. Therefore, by deleting components that are only displayed in viewpoints that the user does not need, the size of the 3D CG model can be reduced.

[0045] (Modification Example 3) In the above-described embodiment, components to be deleted are photographed in the 3D CAD model, the image search program 15 searches for an image similar to the CAD photographed image, and the searched actual image is pasted onto the 3D CG model by the image pasting program 16. However, the search for the actual image and the pasting onto the 3D CG model are not essential configurations, and these may be omitted. In this case, steps S309 to S311 shown in FIG. 3 become unnecessary, and step S312 is executed after step S308.

[0046] (Modification Example 4) In the above-described embodiment, after generating the 3D CG model, this 3D CG model is displayed using the 3D CG program 12. However, the display of the 3D CG model is not an essential configuration, and the display may not be performed. In this case, the created 3D CG model may be stored in the 3D CG model database 42 to complete the process, or the created 3D CG model may be transmitted outside the arithmetic unit 1 via the communication device 56 to complete the process.

[0047] (Modification Example 5) In the above-described embodiment, a CAD photographed image including the component to be deleted is photographed, and this CAD photographed image or a similar actual image is pasted onto the 3D CG model. However, the pasting of the CAD photographed image and the similar actual image onto the 3D CG model is not an essential configuration, and it is not necessary to paste an image corresponding to the component to be deleted onto the 3D CG model.

[0048] In each of the above-described embodiments and modification examples, the configuration of the functional blocks is merely an example. Some functional configurations shown as separate functional blocks may be integrally configured, or the configuration represented by one functional block diagram may be divided into two or more functions. Also, a configuration may be adopted in which a part of the functions possessed by each functional block is provided by other functional blocks.

[0049] In each of the above-described embodiments and modified examples, the arithmetic unit 1 may include an input / output interface (not shown), and when necessary, a program may be read from another device via the input / output interface and a medium that can be used by the arithmetic unit 1. Here, the medium refers to, for example, a storage medium detachable from the input / output interface, or a communication medium, that is, a network such as wired, wireless, optical, or a carrier wave or digital signal propagating through the network. Also, part or all of the functions realized by the program may be realized by a hardware circuit or FPGA.

[0050] Each of the above-described embodiments and modified examples may be combined. Although various embodiments and modified examples have been described above, the present invention is not limited to these contents. Other aspects conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

[0051] 1: Arithmetic unit 11: CAD program 12: 3D CG program 13: Converter 14: Component identification program 15: Image search program 16: Image pasting program 41: CAD model database 42: 3D CG model database 43: Photo database 44: CAD photographed image database 45: Application table

Claims

1. A calculation system comprising: a part identification unit that identifies a part to be deleted from a 3D CAD model based on conditions; a captured image generation unit that generates a CAD captured image, which is a rendering image including the part to be deleted, using the 3D CAD model; a part deletion unit that deletes the part to be deleted determined by the part identification unit from the 3D CAD model to generate a deleted CAD model; a converter that converts the deleted CAD model into a 3D CG model; and an image pasting unit that pastes an image based on the CAD captured image onto the 3D CG model.

2. The calculation system according to claim 1, further comprising an image search unit that searches for similar real images, which are images similar to the CAD-captured image, with real images, which are images obtained by photographing a real object, as the target, wherein the image attachment unit attaches the similar real image to the 3D CG model when the image search unit can obtain the similar real image, and attaches the CAD-captured image to the 3D CG model when the image search unit cannot obtain the similar real image.

3. The calculation system according to claim 1, wherein the condition is that the size of the component is less than or equal to a predetermined threshold, and the size includes at least one of length, area, and volume.

4. The calculation system according to claim 3, wherein the predetermined threshold is determined based on a use case of the 3D CG model selected by the user, or is manually set by the user.

5. The calculation system according to claim 1, wherein the condition is specified by the attributes of a part, the attributes include at least one of manufacturer, type, shape, hierarchy, and viewpoint.

6. The calculation system according to claim 5, wherein the attribute is a viewpoint, and the component identification unit identifies components that are not displayed in the viewpoint selected by the user as components to be deleted.

7. The calculation system according to claim 1, further comprising a 3D CG program for displaying the 3D CG model.

8. A method for generating a 3D computer-generated CG model, comprising: identifying a part to be deleted from a 3D CAD model based on conditions; generating a CAD image, which is a rendering image including the part to be deleted, using the 3D CAD model; deleting the determined part to be deleted from the 3D CAD model to generate a deleted CAD model; converting the deleted CAD model into a 3D CG model; and pasting an image based on the CAD image onto the 3D CG model.

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