JP7682471B2 - Method for creating modeling data, modeling data generating device, and modeling system - Google Patents

Description

The present invention relates to a method for creating modeling data, a modeling data generating device, and a modeling system.

Conventionally, there is known a modeling device (3D printer) that uses an inkjet head to model an object (see, for example, Patent Document 1). In such a modeling device, for example, an object is modeled by a layered modeling method, by stacking multiple layers of ink formed by the inkjet head.

JP 2015-071282 A

When modeling an object using a modeling device, the object is usually modeled using a modeling material that is prepared in advance to match the configuration of the modeling device. For example, when modeling is performed using an inkjet head, ink for the inkjet head is used as the modeling material. In this case, the texture of the object is considered to be determined by the modeling material. In contrast, in recent years, due to the expansion of applications of modeling devices, it is sometimes desired to model objects with higher design quality. In this case, for example, it is sometimes desired to model objects with a wider variety of textures. Therefore, an object of the present invention is to provide a modeling data creation method, a modeling data generation device, and a modeling system that can solve the above problems.

The inventors of the present application have conducted extensive research into methods for forming three-dimensional objects with various textures using a modeling device. By conducting various experiments on the perception system by which humans perceive textures, they have found that even if the physical characteristics corresponding to the texture are not changed, the observer can be made to perceive a desired texture by changing the way the surface of the object is colored. More specifically, when observing an object, a shadow is usually generated on the surface of the object depending on the shape of the object due to the surrounding environmental light. In addition, in this case, the way the shadow is generated can be considered to reflect physical characteristics such as the scattering phenomenon that occurs near the surface of the object and the state of light transport. In response to this, the inventors of the present application have conceived of changing the texture perceived by the observer in a so-called optical illusion by coloring the surface of the object according to the shadow generated on the surface of the object, so that the observer can visually recognize the shadow as if it were generated in a state different from the original shadow.

Furthermore, the inventor of the present application has, through further intensive research, found the features necessary to obtain such effects, and arrived at the present invention. In order to solve the above problems, the present invention is a method for creating modeling data, which is data indicating an object to be modeled by a modeling device, and includes a shape determination step for determining the shape of the object, a shading data acquisition step for acquiring shading data, which is data indicating shading that occurs on the surface of the object according to the shape of the object, and a surface color determination step for determining the color to be applied to each position on the surface of the object based on the shading data.

When configured in this way, the color to be applied to each position on the surface of the object can be determined based on the shading data, so that the observer can visually recognize the state of the object as if the shading were occurring in a state different from the original shading. This also makes it possible, for example, to change the texture perceived by the observer. Therefore, with this configuration, for example, it is possible to appropriately create objects that express a variety of textures. This also makes it possible, for example, to more appropriately create objects with a desired texture or objects with a highly designed appearance.

In this configuration, the color to be applied to each position on the surface of the molded object may be, for example, only one color. In this case, determining the color to be applied to each position on the surface of the molded object can be thought of as, for example, determining the color density. Determining the color density can be thought of as, for example, determining the gradation of the color at each position. Also, determining the color density can be thought of as, for example, determining the brightness of the color. Each position on the surface of the molded object may be colored (for example, full color). In this case, determining the color to be applied to each position on the surface of the molded object may be, for example, determining the color density for each of multiple colors that are the basic colors of the color expression.

In this configuration, in the shadow data acquisition stage, a shadow image, which is an image showing a shadow occurring on the surface of the shaped object, is acquired as the shadow data. In the surface color determination stage, for example, an inverted image, which is an image obtained by performing gradation inversion on the shadow image, may be generated. In this case, for example, based on the inverted image, a color to be colored at each position on the surface of the shaped object is determined. With this configuration, for example, the impression given to the observer by the shadow occurring on the shaped object can be appropriately changed. In addition, this allows, for example, the texture perceived by the observer of the shaped object to be appropriately changed. In this case, in the surface color determination stage, for example, based on the inverted image, a color to be colored at each position on the surface of the shaped object is determined so that the influence of the shadow occurring on the surface of the shaped object is reduced and perceived by the observer according to the shape of the shaped object. With this configuration, for example, the texture perceived by the observer of the shaped object can be appropriately changed. In addition, for example, processing other than gradation inversion can be performed on the shadow image. In this case, for example, in addition to gradation inversion, processing such as limiting the number of gradations and gamma correction can be further performed. This configuration allows you to vary the effects of shadows, for example.

In addition, if the texture perceived by the observer due to the influence of shadows generated on the surface of the object by light irradiated thereon is defined as the perceived texture, and the perceived texture perceived in a formed object with a uniform color at each position on the surface is defined as a uniform color texture, then in the surface color determination stage, for example, a color to be applied to each position on the surface of the formed object is determined so that the observer perceives a perceived texture different from the uniform color texture. With this configuration, for example, it is possible to appropriately change the texture perceived by the observer of the formed object. Furthermore, for example, a texture related to translucency (semi-transparency) can be used as the perceived texture. In this case, in the surface color determination stage, for example, a color to be applied to each position on the surface of the formed object is determined so that the perceived texture is different from the uniform color texture, and at least a portion of the translucency of the formed object is perceived to be higher. With this configuration, for example, it is possible to appropriately express high translucency as the texture of the formed object.

In addition, in the shape determination stage, the shape of the object is determined, for example, based on shape data, which is data indicating the shape of the object. Then, in the surface color determination stage, for example, a texture is generated to be attached to the surface of the three-dimensional shape indicated by the shape data. In this case, it is possible to generate, as this texture, a texture indicating the color to be applied to each position on the surface of the object. With this configuration, for example, it is possible to appropriately specify the color to be applied to each position on the surface of the object. In this case, the method for creating the modeling data further includes, for example, a modeling data generation stage in which modeling data is generated based on the shape data and the texture. With this configuration, for example, it is possible to appropriately create the modeling data.

In addition, in the modeling data generation stage, for example, modeling data showing a modeled object having a configuration with a region for changing the texture of the modeled object may be generated. In addition, as such modeling data, for example, modeling data showing a modeled object having a scattering region containing a scatterer, which is an inclusion with a property of scattering light, may be generated. In this case, the scattering region is, for example, a region containing a scatterer and having the amount of the scatterer contained per unit volume differ depending on the position. By configuring in this way, for example, the actual texture of the modeled object can be changed in various ways. In addition, in this case, by combining determining the color to be applied to each position on the surface of the modeled object based on the shading data and making the actual texture of the modeled object different depending on the scattering region, the texture perceived by the observer of the modeled object can be changed in more diverse ways. In addition, in this case, it is also considered that the way in which the scattering region is formed is determined based on the shading data. More specifically, in this case, in the modeling data generation stage, for example, the amount of the scatterer contained per unit volume at each position of the scattering region is determined based on the shading data, thereby generating modeling data showing a modeled object having a scattering region. With this configuration, for example, it is possible to more appropriately change the impression that the observer receives depending on the shadows cast on the object.

In addition, in the shadow data acquisition stage, the shadow data is acquired by computer simulation using, for example, the AO method (ambient occlusion method). With this configuration, for example, the shadow data can be easily and appropriately acquired. In the shadow data acquisition stage, the shadow data may be acquired by computer simulation using a method other than the AO method. Also, the shadow data may be acquired by, for example, actually performing measurements, without using computer simulation. In this case, in the shadow data acquisition stage, for example, a three-dimensional object having the same shape as the shape determined in the shape determination stage is created, and the shadow data is acquired based on the shadow generated on the surface of the three-dimensional object by irradiating the three-dimensional object with light. With this configuration, for example, the shadow data can be appropriately acquired with high accuracy. In this case, it is considered that the three-dimensional object to be measured is modeled using, for example, a modeling device. Also, this three-dimensional object may be created by a method other than modeling using a modeling device. Also, as the modeling data, for example, data indicating an existing three-dimensional object that exists before the creation of the modeling data is started can be created. In such a case, it is possible to obtain the shadow data, for example, by using an existing three-dimensional object. More specifically, in this case, in the shadow data acquisition stage, the shadow data is obtained based on the shadows that appear on the surface of the existing three-dimensional object. Even in such a configuration, it is possible to obtain the shadow data appropriately with high accuracy, for example.

In addition, as a configuration of the present invention, it is also possible to use a modeling data generation device or modeling system having the same characteristics as described above. In these cases, it is possible to obtain, for example, the same effects as described above.

The present invention makes it possible to appropriately create objects that express a variety of textures, for example.

1A is a diagram showing an example of a modeling system 10 according to an embodiment of the present invention. Fig. 1A shows an example of the configuration of the modeling system 10. Fig. 1B shows an example of the configuration of a main part of a modeling device 12. Fig. 1C shows an example of the configuration of a head unit 102. 2A and 2B are diagrams illustrating the configuration of a model 50 to be modeled by the modeling apparatus 12. Fig. 2A shows an example of the configuration of the model 50. Fig. 2B shows a modified example of the configuration of the model 50. 3A and 3B are diagrams illustrating an operation of generating modeling data in the control PC 14. Fig. 3A is a flowchart showing an example of the operation of generating modeling data. Fig. 3B is a flowchart showing an example of the operation of generating a texture for adjusting texture. 4A and 4B are diagrams for explaining the AO texture and the texture for texture adjustment in more detail, in which Fig. 4A shows an example of the AO texture, and Fig. 4B shows an example of the texture for texture adjustment. 13 is a flowchart showing another modified example of the operation of generating a texture for adjusting the texture. 6A and 6B are diagrams for explaining in more detail a modified example of the object 50. Fig. 6A shows an example of the configuration of the object 50 including a scattering region 156. Fig. 6B shows another example of the configuration of the object 50 including a scattering region 156.

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows an example of a modeling system 10 according to an embodiment of the present invention. FIG. 1(a) shows an example of the configuration of the modeling system 10. In this example, the modeling system 10 is a modeling system that models a three-dimensional object, and includes a modeling device 12 and a control PC 14. The object modeled by the modeling system 10 can be considered to be, for example, a three-dimensional structure.

The modeling device 12 is a device that executes modeling of a modeled object, and models the modeled object according to the control of the control PC 14. In this example, the modeling device 12 is a full-color modeling device that can model a full-colored object, receives modeling data representing the object to be modeled from the control PC 14, and models the object based on the modeling data. The control PC 14 is a computer (host PC) that controls the operation of the modeling device 12, and controls the modeling operation by the modeling device 12 by supplying the modeling data to the modeling device 12. In this example, the control PC 14 is an example of a modeling data generating device, and generates modeling data representing a modeled object in which at least a part of a surface in which the color is visible from the outside is colored, and supplies the data to the modeling device 12. The operation of generating modeling data in the control PC 14 will be explained in more detail later.

In this example, the modeling system 10 is composed of multiple devices, namely, the modeling device 12 and the control PC 14. In a modified example of the modeling system 10, the modeling system 10 may be composed of a single device. In this case, for example, it is conceivable to configure the modeling system 10 with a single modeling device 12 that includes the functions of the control PC 14. Furthermore, the modeling system 10 may further include devices other than the modeling device 12 and the control PC 14.

Next, the configuration of the modeling device 12 will be described. FIG. 1B shows an example of the configuration of the main parts of the modeling device 12. In this example, the modeling device 12 is a 3D printer that models the object 50 by additive manufacturing, and has a head unit 102, a modeling table 104, a scan drive unit 106, and a control unit 110. In this case, the additive manufacturing method can be considered to be, for example, a method of modeling the object 50 by stacking layers formed of the material for modeling. In addition, except for the points described below, the modeling device 12 may have the same or similar configuration as a known modeling device that performs modeling by ejecting droplets that are the material for the object 50 using an inkjet head. In addition, the modeling device 12 may further include various configurations necessary for modeling the object 50, in addition to the configuration shown in the figure.

The head unit 102 is configured to eject the material of the model 50. In this example, ink is used as the material of the model 50. The ink can be considered to be, for example, a functional liquid. The ink can also be considered to be, for example, a liquid ejected from an inkjet head. In this example, the head unit 102 ejects ink that hardens according to predetermined conditions from multiple inkjet heads as the material of the model 50. Then, by hardening the ink after landing, each layer that constitutes the model 50 is formed by stacking, and the model is formed by a layered modeling method. In this example, as such ink, ultraviolet-curable ink (UV ink) that hardens from a liquid state by irradiation with ultraviolet rays is used. In addition, the head unit 102 ejects the material of the support layer 52 in addition to the material of the model 50. As a result, the head unit 102 forms the support layer 52 around the periphery of the model 50 as necessary. The support layer 52 can be considered, for example, as a laminated structure that supports at least a portion of the object 50 during modeling. The support layer 52 is formed as necessary during modeling of the object 50, and is removed after modeling is completed.

The modeling table 104 is a platform-like member that supports the object 50 being modeled, and is disposed in a position facing the inkjet head in the head unit 102. The object 50 being modeled and the support layer 52 are placed on the upper surface of the modeling table 104. In this example, the modeling table 104 is configured to be movable in the stacking direction (Z direction in the figure), and is driven by the scan drive unit 106 to move in the stacking direction in accordance with the progress of modeling of the object 50. In this case, the stacking direction can be considered to be, for example, the direction in which the material for modeling is stacked in the additive modeling method. In this example, the stacking direction is perpendicular to the main scanning direction (Y direction in the figure) and sub-scanning direction (X direction in the figure) that are preset in the modeling device 12.

The scan driver 106 is a driver that causes the head unit 102 to perform a scanning operation in which the head unit 102 moves relative to the object 50 being modeled. In this example, the movement relative to the object 50 being modeled can be considered to be, for example, a movement relative to the modeling table 104. Also, causing the head unit 102 to perform a scanning operation can be considered to be, for example, causing the inkjet head of the head unit 102 to perform a scanning operation. In this example, the scan driver 106 causes the head unit 102 to perform a main scanning operation (Y scan), a sub-scanning operation (X scan), and a stacking direction scanning operation (Z scan) as a scanning operation. In this case, the main scanning operation can be considered to be, for example, an operation of ejecting ink while moving in the main scanning direction relative to the object 50 being modeled. The sub-scanning operation can be considered to be, for example, an operation of moving relative to the object 50 being modeled in the sub-scanning direction perpendicular to the main scanning direction. The sub-scanning operation can also be considered as, for example, an operation of moving in the sub-scanning direction relative to the modeling table 104 by a preset feed amount. In this example, the scan driver 106 causes the head unit 102 to perform a main scanning operation and a sub-scanning operation, thereby forming an ink layer on the head unit 102. The stacking direction scanning operation can also be considered as, for example, an operation of moving in the stacking direction relative to the modeled object 50 being modeled. The scan driver 106 adjusts the relative position of the inkjet head to the modeled object 50 being modeled in the stacking direction by causing the head unit 102 to perform a stacking direction scanning operation in accordance with the progress of the modeling operation.

The control unit 110 includes, for example, the CPU of the modeling device 12, and controls each part of the modeling device 12 to control the modeling operation of the object 50. In this example, the control unit 110 generates slice data, which is data showing a cross section of the object 50 to be modeled, based on the modeling data received from the control PC 14. Then, in the operation of forming each ink layer that constitutes the object 50, the control unit 110 controls the operation of each inkjet head in the head unit 102 based on the slice data, thereby causing each inkjet head to eject the ink used to model the object. According to this example, for example, the modeling of the object 50 can be performed appropriately.

Next, the configuration of the head unit 102 in the modeling device 12 will be described in more detail. FIG. 1C shows an example of the configuration of the head unit 102. In this example, the head unit 102 has a plurality of inkjet heads 202, a plurality of ultraviolet light sources 204, and a flattening roller 206. The inkjet heads 202 are inkjet head 202s, inkjet head 202w, inkjet head 202y, inkjet head 202m, inkjet head 202c, inkjet head 202k, and inkjet head 202t, as distinguished by the letters s to t in the figure. These inkjet heads 202 are aligned in the main scanning direction with their positions in the sub-scanning direction aligned. Each inkjet head 202 has a nozzle row on the surface facing the modeling table 104, in which a plurality of nozzles are aligned in a predetermined nozzle row direction. In this example, the nozzle row direction is parallel to the sub-scanning direction.

Of these inkjet heads 202, inkjet head 202s is an inkjet head that ejects the material of support layer 52. For example, a known material for support layers can be suitably used as the material of support layer 52. Inkjet head 202w is an inkjet head that ejects white (W color) ink. In this example, white ink is an example of a light-reflective ink, and is used, for example, when forming a region (light-reflecting region) that has the property of reflecting light in the model 50. This light-reflecting region reflects light incident from outside the model 50, for example, when coloring the surface of model 50 in full color expression or the like. Full color expression can be considered, for example, as color expression performed by a possible combination of subtractive color mixing using process color inks.

Inkjet head 202y, inkjet head 202m, inkjet head 202c, and inkjet head 202k (hereinafter referred to as inkjet heads 202y-k) are inkjet heads for coloring used when forming a colored object 50. More specifically, inkjet head 202y ejects yellow (Y) ink. Inkjet head 202m ejects magenta (M) ink. Inkjet head 202c ejects cyan (C) ink. Inkjet head 202k ejects black (K) ink. In this example, each of the colors YMCK is an example of a process color. Inkjet head 202t is an inkjet head that ejects clear ink. The clear ink can be considered to be, for example, an ink that is colorless and transparent (T) to visible light. The clear ink can also be considered to be, for example, an ink to which no coloring material is intentionally added.

The multiple ultraviolet light sources 204 are light sources (UV light sources) for curing ink, and generate ultraviolet light that cures ultraviolet curable ink. In this example, the multiple ultraviolet light sources 204 are arranged at one end side and the other end side of the head unit 102 in the main scanning direction, sandwiching the row of inkjet heads 202 between them. For example, a UV LED (ultraviolet LED) or the like can be suitably used as the ultraviolet light source 204. It is also possible to use a metal halide lamp or a mercury lamp as the ultraviolet light source 204. The flattening roller 206 is a flattening means for flattening the ink layer formed during the modeling of the model 50. The flattening roller 206 flattens the ink layer by contacting the surface of the ink layer during, for example, a main scanning operation and removing a portion of the ink before curing. By using the head unit 102 configured as described above, for example, the ink layer constituting the model 50 can be appropriately formed. Furthermore, by forming multiple layers of ink one on top of the other, it is possible to appropriately form the modeled object 50, for example.

The specific configuration of the head unit 102 is not limited to the configuration described above, and can be modified in various ways. For example, the head unit 102 may further include inkjet heads for colors other than those described above as inkjet heads for coloring. The arrangement of the multiple inkjet heads in the head unit 102 can also be modified in various ways. For example, some inkjet heads may be shifted in position in the sub-scanning direction from the other inkjet heads.

Next, the configuration of the object 50 formed by the modeling device 12 of this example will be described in more detail. FIG. 2 is a diagram illustrating the configuration of the object 50 formed by the modeling device 12. FIG. 2(a) is a diagram showing an example of the configuration of the object 50, and shows an example of the configuration of the X-Y cross section, which is a cross section of the object 50 perpendicular to the stacking direction (Z direction). In this case, the Y-Z cross section and the X-Z cross section of the object 50 perpendicular to the X direction and Y direction also have the same configuration. Also, in FIG. 2, for convenience of illustration, an example of the configuration of the object 50 is shown for an object 50 with a simple shape. During actual modeling, the modeling device 12 can also model an object 50 with a more complex shape. More specifically, the modeling device 12 can be used to model an object 50 that represents a natural object such as a human being or an animal.

In this example, the modeling device 12 uses the inkjet heads 202y-k (see FIG. 1) and the like to model the object 50 with a colored surface. The coloring of the surface of the object 50 can be considered to mean, for example, that at least a part of the area of the object 50 where the color can be seen from the outside is colored. In this case, the modeling device 12 models the object 50 with a light reflecting area 152 and a colored area 154, for example, as shown in the figure. In this case, the control PC 14 (see FIG. 1) generates modeling data representing the object 50 with these areas and supplies it to the modeling device 12, causing the modeling device 12 to model the object 50. In addition, the modeling device 12 forms a support layer 52 (see FIG. 1) around the object 50, etc., as necessary.

The light reflecting region 152 is a light reflecting region for reflecting light incident from the outside of the model 50 through the colored region 154. In this example, the modeling device 12 forms the light reflecting region 152 inside the model 50 using white ink ejected from the inkjet head 202w (see FIG. 1). In this example, the modeling device 12 also forms the light reflecting region 152 that also serves as the internal region. In this case, the internal region can be considered, for example, as a region that constitutes the interior of the model 50. In a modified example of the configuration of the model 50, the internal region may be formed as a region separate from the light reflecting region 152. In this case, the modeling device 12 forms the internal region using, for example, any ink other than the material of the support layer 52. Also, the light reflecting region 152 is formed around the internal region.

The colored region 154 is a region that is colored by the coloring inks discharged from the inkjet heads 202y-k. In this example, the modeling device 12 forms the colored region 154 around (outside) the light reflecting region 152 using the coloring inks discharged from the inkjet heads 202y-k and the clear ink discharged from the inkjet head 202t (see FIG. 1). In this case, the modeling device 12 expresses various colors by, for example, adjusting the amount of coloring ink of each color discharged to each position. With this configuration, for example, coloring with various colors (for example, full color coloring) can be performed for each position on the surface of the modeled object 50. Also, in this case, by changing the color to be colored depending on the position, various patterns, characters, etc. can be drawn on the surface of the modeled object 50. Also, in this example, clear ink is used to compensate for the change in the amount of coloring ink caused by the difference in color. With this configuration, for example, each position of the colored region 154 can be appropriately colored with a desired color.

Depending on the application of the molded object 50, it may be possible to use only one color for coloring each position on the surface of the molded object 50. In this case, for example, it is possible to form the colored region 154 using one color of coloring ink (e.g., K ink) and clear ink. It is also possible to vary the intensity of the color colored with that one color of coloring ink depending on the position in the colored region 154. In this case, it is possible to change the amount of coloring ink ejected per unit volume to change the color intensity. It is also possible to use the clear ink to compensate for changes in the amount of coloring ink that result in differences in color intensity.

In addition, in a modified example of the configuration of the model 50, as shown in FIG. 2B, for example, another region may be formed between the light reflecting region 152 and the colored region 154. FIG. 2B is a diagram showing a modified example of the configuration of the model 50. In this modified example, the model 50 includes a light reflecting region 152, a scattering region 156, and a colored region 154. In this case, the light reflecting region 152 and the colored region 154 are, for example, the same or similar regions as the light reflecting region 152 and the colored region 154 in FIG. 2A. The scattering region 156 is formed between the light reflecting region 152 and the colored region 154. In this case, the control PC 14 generates modeling data representing the model 50 including these regions and supplies the data to the modeling device 12, thereby causing the modeling device 12 to model the model 50.

In this modified example, the scattering region 156 is a region formed using white ink and clear ink. In this case, the coloring material (e.g., pigment, etc.) contained in the white ink can be considered as an example of a scattering body, which is an inclusion that has the property of scattering light. The scattering region 156 can be considered as a region that has the property of scattering light by containing a scattering body at a ratio determined according to the usage ratio of the clear ink and the white ink. In this configuration, by forming the scattering region 156 inside the colored region 154, for example, the actual texture of the model 50 can be changed in various ways. In addition, this allows the texture of the model 50 perceived by the observer of the model 50 to be changed in a more diverse way than when the scattering region 156 is not formed. Therefore, the scattering region 156 can be considered as a region for changing the texture of the apparent model 50 in a more diverse way. In a further modified example of the configuration of the model 50, it is also possible to omit the light reflecting region 152. In this case, the scattering region 156 can be considered to be a region that also functions as the light reflecting region 152. In this case, the model 50 includes, for example, an internal region, the scattering region 156, and a colored region 154. A modified example that uses the scattering region 156 will be described in more detail later.

Next, the characteristics of the object 50 formed based on the modeling data by the modeling device 12 of this example, and the operation of generating the modeling data by the control PC 14 will be described in more detail. As explained above, the modeling device 12 of this example uses ink ejected from an inkjet head as the material for the object 50. In this case, the texture of the object 50 formed can be considered to reflect the characteristics of the ink. However, depending on the use of the object 50, it may be desired to express a wider variety of textures in the object 50.

In this regard, the inventor of the present application conducted various experiments on the perception system by which humans perceive texture, and found that even if the physical characteristics corresponding to the texture are not changed, the observer can be made to perceive a desired texture by changing the way the surface of the model is colored. More specifically, for example, when observing a three-dimensional object such as the model 50 formed by the modeling device 12, a shadow is generated on the surface of the object according to its shape, etc. due to the surrounding environmental light. In addition, in this case, the way the shadow is generated can be considered to reflect physical characteristics such as the scattering phenomenon and the state of light transport that occur near the surface of the object. Therefore, for example, if the appearance of the shadow changes, it is considered that the texture perceived by the observer will also change. Therefore, the inventor of the present application thought of changing the texture perceived by the observer in a so-called optical illusion by coloring the surface of the model 50 according to the shadow that actually occurs on the surface of the model, so that the observer can visually perceive the shadow as if it occurs in a state different from the original shadow. In this case, coloring according to the shadows that appear on the surface of the shaped object 50 can be considered, for example, as coloring that changes the appearance of the shadows that actually appear. The inventors of the present application have also considered using a method that uses a texture that indicates the color to be applied to the surface of the shaped object 50 (a texture control method) as a method for changing the apparent texture in this way. Such a method can also be considered, for example, as a method of artificially reproducing a desired texture using a texture for adjusting the texture.

In this case, it is also possible to generate modeling data by the operation shown in FIG. 3, for example. FIG. 3 is a diagram illustrating the operation of generating modeling data in the control PC 14. FIG. 3(a) is a flowchart illustrating an example of the operation of generating modeling data. As described above, in this example, the control PC 14 generates modeling data representing a model having at least a portion of a surface whose color is visible from the outside that is colored, and supplies the data to the modeling device 12. In this case, the apparent texture of the model 50 is changed using a texture adjustment texture.

More specifically, in this case, the control PC 14 acquires 3D model data by receiving data created in advance by a user or the like from the outside (S102). This also causes the control PC 14 to determine the shape of the object 50 to be formed by the forming device 12. The 3D model data can be considered to be, for example, data that at least indicates a three-dimensional shape. In this example, the operation of step S102 is an example of the operation of the shape determination stage (shape determination process). The control PC 14 acquires 3D model data that includes at least shape data that is data that indicates the shape of the object 50, for example. Then, based on this shape data, the control PC 14 determines the shape of the object 50 to be processed in the subsequent operations.

In this example, the 3D model data acquired by the control PC 14 can be considered to be, for example, 3D data showing the object 50 to be modeled in a state where the texture has not been adjusted. As such 3D model data, for example, general-purpose 3D data that does not depend on the model or specifications of the modeling device 12 can be preferably used. As such 3D model data, for example, data that is the same as or similar to 3D model data used as input data in a known modeling method can be preferably used. In addition, the control PC 14 receives 3D model data from another computer, for example, via a network. The control PC 14 may receive 3D model data via a recording medium or the like. In addition, it is also possible to generate 3D model data in the control PC 14 in response to a user's operation, rather than receiving it from outside the control PC 14. In this case, the operation of generating 3D model data in the control PC 14 can be considered to be the operation of acquiring 3D model data.

As described above, the modeling device 12 models, for example, a modeled object 50 whose surface is colored. In this case, in step S102, the control PC 14 acquires, for example, 3D model data indicating the shape and color of the modeled object 50. More specifically, in this case, the 3D model data includes, for example, shape data indicating the shape of the modeled object 50 and a texture for surface color, which is a texture indicating the color of each position on the surface of the modeled object 50. In this case, the texture for surface color is a texture different from the texture for texture adjustment described above, and indicates the color of each position on the surface of the modeled object 50 in a state where texture adjustment has not been performed. As such a texture for surface color, for example, a texture indicating an image to be attached to the three-dimensional shape indicated by the shape data can be used.

After acquiring the 3D model data in step S102, the control PC 14 generates a texture for texture adjustment based on the shape of the object 50 (S104). In this example, the operation of step S104 is an example of the operation of the shadow data acquisition stage (shadow data acquisition process). In step S104, the control PC 14 acquires shadow data, which is data indicating shadows occurring on the surface of the object 50, based on the shape data included in the 3D model data. Then, a texture for texture adjustment is generated based on the shadow data. In this case, the shadows occurring on the surface of the object 50 can be considered to be, for example, shadows occurring on the surface of the object 50 depending on the shape of the object 50. The shadows occurring on the surface of the object 50 depending on the shape of the object 50 can be considered to be, for example, shadows occurring on the surface of the object 50 depending on the shape of the object 50 under a predetermined ambient light. The characteristics of the texture for texture adjustment used in this example and the operation of generating the texture for texture adjustment in step S104 will be described in more detail later.

After generating the texture for texture adjustment in step S104, the control PC 14 generates printing data based on the 3D model data acquired in step S102 and the texture for texture adjustment generated in step S104 (S106). In this example, the operation of step S106 is an example of the operation of the surface color determination stage (surface color determination process) and the printing data generation stage (printing data generation process). The printing data generated by the control PC 14 in step S106 can be considered to be, for example, data indicating the shape and color of the object 50 in a state in which the texture has been adjusted. In this example, the control PC 14 determines the color to be applied to each position on the surface of the object 50 during the operation of generating the printing data. In this case, the operation of determining the color to be applied to each position on the surface of the object 50 can be considered to correspond to the operation in the surface color determination stage. Also, as described above, in step S104, the control PC 14 generates the texture for texture adjustment based on the shading data. Therefore, the operation of the control PC 14 in step S106 can be considered to determine the color to be applied to each position on the surface of the model 50 based on the shading data, for example.

In this case, determining the color to be applied to each position on the surface of the object 50 can be considered to be, for example, determining the color density. Determining the color density can be considered to be, for example, determining the gradation of the color at each position. The gradation of the color can be considered to be, for example, a grayscale gradation indicating the density of the color. Determining the color density can be considered to be, for example, determining the brightness of the color. When coloring the surface of the object 50, determining the color to be applied to each position on the surface of the object 50 can be, for example, determining the color density for each of a plurality of colors that are the basic colors of the color expression.

In addition, in this example, the control PC 14 generates modeling data that indicates the shape and color of the modeled object 50 in a format that is not dependent on, for example, the model or specifications of the modeling device 12. More specifically, as described above, in this example, the control unit 110 of the modeling device 12 (see FIG. 1) generates slice data based on the modeling data. In this case, the operation of generating slice data can be considered, for example, as an operation of generating data in a format that matches the model or specifications of the modeling device 12. In addition, in this case, since conversion to data in a format that matches the model or specifications of the modeling device 12 is performed when the slice data is generated, the modeling data generated by the control PC 14 can be data in a format that is not dependent on the model or specifications of the modeling device 12.

In addition, in a modified example of the operation of generating the modeling data, the control PC 14 may generate modeling data in a format that depends on the model and specifications of the modeling device 12. Depending on the configuration of the modeling system 10 (see FIG. 1), it is also possible to generate slice data in the control PC 14. In this case, the data used as input data for the process of generating slice data can be considered to be the modeling data generated in step S106. The slice data can also be considered to be data indicating the shape and color of the model 50. Therefore, the operation of generating slice data can also be considered to be an operation of generating modeling data.

In addition, in step S106, the control PC 14 determines the color to be applied to each position on the surface of the object 50, for example, by generating a texture that matches the shape of the object 50 indicated by the shape data included in the 3D model data acquired in step S102. In this case, the shape and color of the object 50 can be considered to be indicated by including this shape data and texture in the printing data. This texture can be considered, for example, as a texture indicating the color to be applied to each position on the surface of the object 50. In addition, this texture is, for example, a texture (hereinafter referred to as a texture for printing) that is generated separately from the texture for surface color and the texture for texture adjustment described above.

More specifically, in this example, the control PC 14 generates a modeling texture based on the texture for texture adjustment generated in step S104. In this case, the modeling texture can be considered to indicate the color to be colored at each position on the surface of the modeled object 50 after the texture adjustment is performed using the texture for texture adjustment. In addition, if the 3D model data acquired in step S102 includes a texture for surface color, the control PC 14 generates a modeling texture based on the texture for texture adjustment and the texture for surface color. In addition, the control PC 14 generates a modeling texture that reflects the color specified in the 3D model data and indicates the texture after adjustment. The operation of generating a modeling texture based on the texture for texture adjustment and the texture for surface color can also be considered to be, for example, an operation of generating a modeling texture by adjusting the texture for surface color based on the texture for texture adjustment. In addition, in this example, the modeling texture is a texture that indicates an image to be pasted on the surface of the three-dimensional shape indicated by the shape data. In this case, the control PC 14 generates a modeling texture that corresponds to the shape data, and generates modeling data based on the shape data and the modeling texture. According to this example, for example, it is possible to appropriately specify the color to be applied to each position on the surface of the model 50 while adjusting the texture perceived by the observer of the model 50. This also makes it possible to appropriately create modeling data, for example.

Next, the characteristics of the texture for texture adjustment used in this example and the operation of generating the texture for texture adjustment in step S104 will be described in more detail. As described above, in this example, the control PC 14 acquires shading data, which is data indicating shading that occurs on the surface of the shaped object 50, based on the shape data included in the 3D model data. Then, the control PC 14 generates the texture for texture adjustment based on the shading data. Also, in this example, the control PC 14 generates the texture for texture adjustment to adjust translucency (semi-transparency), which is an example of texture.

Here, since translucency is a texture that exists in many places in nature and is an important texture related to, for example, human skin, it is desirable to reproduce it with high quality when forming the model 50. In addition, in this regard, when a human feels translucency, it can be considered that it is influenced by, for example, non-specular contrast, brightness gradient at edges and thin areas, covariance of normal direction and shading, etc. In addition, for non-specular contrast, for example, high-frequency contrast in non-specular areas on the surface of an object observed by a human (hereinafter referred to as an observed object) becomes important. In this case, it can be considered that the high-frequency contrast in non-specular areas is influenced by, for example, how light penetrates into detailed parts. Therefore, it is considered that a change in the state of high-frequency contrast in non-specular areas will cause a change in perceived translucency (perceptual translucency). In addition, when the light transmittance is high in the observed object, it is considered that the contrast will be reversed or random due to the influence of the background, etc. In addition, it can be considered that the brightness gradient at edges and thin areas is also influenced by how light penetrates. Therefore, if the luminance gradient at an edge or a thin region changes, it is believed that the perceived translucency will change. Furthermore, regarding the covariance of the normal direction and the shadow, the normal direction can be considered to be, for example, a direction perpendicular to the surface of the object to be observed, such as the shaped object 50. Furthermore, regarding the covariance of the normal direction and the shadow, when the object to be observed is opaque, for example, it can generally be considered that the normal direction and the shadow covariate. Furthermore, when this covariance is lost, it is believed that humans will perceive translucency. Therefore, for example, it is believed that by intentionally losing this covariance, it is possible to make the observer feel translucency.

As described above, in this example, a texture for adjusting texture is used to reproduce the desired texture in a pseudo manner. In this case, for example, by using a texture for adjusting texture that increases the translucency from the above viewpoint, the translucency perceived by the observer can be increased. More specifically, in this case, for example, a texture for adjusting texture that reverses or makes more random at least a part of the high-frequency contrast in the non-specular area can be used. In addition, for example, a texture for adjusting texture that loses the covariance between the normal direction and the shadow can be used. In this case, the loss of the covariance between the normal direction and the shadow can be considered to be, for example, the loss of consistency between the shape and the shadow distribution. In addition, as such a texture for adjusting texture, for example, a texture that makes the occluded part extremely bright and, conversely, makes the non-occluded part extremely dark can be used. In addition, when using such texture for adjusting texture, for example, the luminance gradient at the edge, thin area, etc. can be considered to approach a state influenced by the way the light penetrates. In this example, taking these points into consideration, a texture for adjusting the texture is used, in which a brightness distribution is determined that takes into account the difficulty of light reaching the shape of the object 50 to be modeled. This also controls, for example, the relative contrast that occurs on the surface of the object 50, thereby changing the apparent translucency. In this case, the control PC 14 generates a texture for adjusting the texture, for example, by the operation shown in FIG. 3(b).

Figure 3 (b) is a flowchart showing an example of the operation of generating a texture for texture adjustment. As described above, in this example, the control PC 14 acquires shading data, which is data indicating shading that occurs on the surface of the shaped object 50, based on the shape data included in the 3D model data acquired in step S102. Then, a texture for texture adjustment is generated based on the shading data. More specifically, in this example, the control PC 14 generates an AO texture by computer simulation using the AO method (Ambient Occlusion method) as an example of shading data (S202).

In this case, the AO texture can be considered as, for example, a texture that takes into account the shape information of the model 50. The AO texture can also be considered as, for example, data that includes information on the shape and degree of occlusion of the model 50. The AO texture can also be considered as, for example, data that indicates a component that reflects ambient light (ambient light component) in a format that can be pasted onto the three-dimensional shape indicated by the shape data. In this example, the AO texture indicates an image that is pasted onto the surface of the three-dimensional shape indicated by the shape data. In this case, the image indicated by the AO texture can be considered as, for example, an image that indicates a shadow caused by ambient light on the surface of the model. The AO method can be considered as, for example, a method of calculating the influence of ambient light from the degree of occlusion in CG technology (computer graphics technology). The generation of the AO texture can be performed, for example, in the same or similar manner as a known method used in CG technology based on the shape data included in the 3D model data acquired in step S102. With this configuration, for example, data to be used as shadow data can be acquired easily and appropriately, for example, automatically. In this example, the AO texture is also an example of a shadow image. The shadow image can be considered, for example, as an image showing shadows that occur on the surface of the model 50. By using such an AO texture, it becomes possible to perform apparent brightness manipulation according to the shape, for example, in a format that can be pasted onto the three-dimensional shape indicated by the shape data. In this example, the control PC 14 generates a grayscale image with a predetermined number of gradations (for example, about 255 gradations) as the AO texture.

In this example, the AO texture is not used as is, but as shown in the figure, the AO texture is subjected to tone inversion (S204), tone number restriction (S206), and gamma correction (S208) to generate a texture for texture adjustment. In this case, the tone inversion process performed in step S204 can be considered as, for example, an operation of generating an inverted image, which is an image in which the tone of the AO texture is inverted. By performing tone inversion on the AO texture, for example, it is possible to brighten the occluded parts in the AO texture, and to simulate the intrusion of light. In addition, in this case, by generating a texture for texture adjustment based on the inverted image, it is possible to, for example, reduce the apparent contrast of the shadows generated on the surface of the model 50. In addition, in this case, for example, it can be considered that the color to be applied to each position on the surface of the model 50 is determined based on the inverted image.

In step S206, the control PC 14 generates a tone-number-limited image, which is a processed image, by limiting the number of tones of the inverted image. In this case, the tone-number-limited process can be performed in the same manner as or similar to a known tone-number conversion process. In this example, the control PC 14 generates a tone-number-limited image by performing a process of changing the inverted image to a preset tone number that is equal to or less than the tone number of the inverted image. In this case, the tone number of the tone-number-limited image can be set to, for example, about 0.4 to 1.0 times (preferably, about 0.5 to 0.9 times) the tone number of the inverted image. More specifically, the tone number of the inverted image can be set to, for example, the same as the tone number of the AO texture. And, for example, if the tone number of the inverted image is 255, the tone number of the tone-number-limited image can be set to about 127 to 255 tones. By generating such a tone-number-limited image and generating a texture for adjusting the texture based on the tone-number-limited image, the magnitude of the influence on the non-occluded portion can be adjusted, for example. In step S208, the control PC 14 performs gamma correction on the tone-limited image to generate a texture for adjusting the texture. In this case, the texture for adjusting the texture can be considered to be, for example, an image that has been subjected to gamma correction on the tone-limited image. In this case, performing gamma correction can increase the effect of the texture for adjusting the texture, for example, on detailed areas that are important to human perception.

According to this example, for example, a texture for adjusting texture can be appropriately generated based on the shading that occurs according to the shape of the model 50. In addition, by generating the modeling data based on the texture for adjusting texture, for example, the impression that the observer receives due to the shading that occurs on the model 50 modeled based on the modeling data can be appropriately changed. This also makes it possible to appropriately change, for example, the texture that the observer perceives of the model 50. More specifically, in this case, by generating the texture for adjusting texture based on the inverted image, for example, it is possible to determine the color to be applied to each position on the surface of the model 50 so that the influence of the shading that occurs on the surface of the model 50 according to the shape of the model 50 is reduced and perceived by the observer. This also makes it possible to appropriately change, for example, the texture that the observer perceives of the model 50. Furthermore, by performing processing such as limiting the number of gradations and gamma correction to generate the texture for adjusting texture, for example, it is possible to change the influence of the shading in various ways.

As described above, in this example, after the texture for texture adjustment is generated based on the AO texture, the texture for modeling is further generated based on the texture for texture adjustment. The AO texture and the texture for modeling can be considered to be, for example, textures indicating an image to be pasted on the surface of the three-dimensional shape indicated by the shape data. In this case, the texture for texture adjustment can also be considered to be, for example, a texture indicating an image to be pasted on the surface of the three-dimensional shape indicated by the shape data. In addition, in the above, for convenience of explanation, an example of the operation in which the gradation number limit and the gamma correction are performed as separate processes has been described. However, in the operation of generating the texture for texture adjustment, for example, the gradation number limit and the gamma correction may be performed simultaneously in one process. In this case, the texture for texture adjustment is generated by changing the pixel value of each pixel of the inverted image by a function using, for example, a parameter indicating the number of gradations limited by the gradation number limit and a parameter indicating the correction amount of the gamma correction. In this case, for example, in the flowchart shown in FIG. 3(b), the operation of step S206 and the operation of step S208 can be considered to be performed simultaneously.

In this example, it is possible to generate textures such as those shown in FIG. 4 as the AO texture and texture for adjusting texture. FIG. 4 is a diagram explaining the AO texture and the texture for adjusting texture in more detail. FIG. 4(a) is a diagram showing an example of the AO texture generated in this example, and shows an example of the AO texture generated when forming a model in the shape of a dragon. In FIG. 4(a), the diagram on the upper left shows a model created by CG with a specified background and without the AO texture applied. The diagram on the lower left shows the model in the diagram on the upper left with the AO texture applied. The diagram on the right shows the AO texture developed into a plane.

As described above, in this example, the texture for texture adjustment is generated by performing each process of tone inversion, tone number limiting, and gamma correction on such an AO texture. In this case, the state of the texture for texture adjustment changes according to the number of tones limited by the tone number limiting process and the correction amount by gamma correction, as shown in FIG. 4B, for example. FIG. 4B is a diagram showing an example of a texture for texture adjustment generated in this example, and shows a sculpted object with a texture for texture adjustment attached and an expanded texture for texture adjustment when the number of tones limited by the tone number limiting process and the correction amount by gamma correction are variously changed. More specifically, the diagram on the upper left side of FIG. 4B shows an example in which the number of tones (R) is limited to 127 by the tone number limiting process and the gamma value (γ), which is the correction amount by gamma correction, is set to 1.5. The diagram on the lower left side shows an example in which the number of tones (R) is limited to 127 and the gamma value (γ) is set to 3. The diagram on the upper right shows an example where the number of gradations (R) is limited to 255 and the gamma value (γ) is set to 1.5. The diagram on the lower right shows an example where the number of gradations (R) is limited to 255 and the gamma value (γ) is set to 3. As can be seen from these diagrams, by varying the number of gradations and the gamma value, it is possible to vary the texture of the shaped object, such as its translucency, in various ways.

Here, as described above, in this example, the control PC 14 generates the printing data in which the surface color is specified by the printing texture. Therefore, it can be considered that the surface color of the object actually formed by the printing device 12 (see FIG. 1) is directly specified by the printing texture, not by the texture for texture adjustment. However, even in this case, by using the printing texture generated based on the texture for texture adjustment, it is possible to generate the printing data so as to reflect the texture shown in FIG. 4(b), for example. More specifically, for example, when coloring the object, in step S102 in FIG. 3(a), 3D model data including the texture for the surface color and the shape data is obtained. In this case, the control PC 14 generates the printing texture based on the texture for texture adjustment and the texture for the surface color. In addition, the control PC 14 thereby generates the printing texture that reflects the color specified in the 3D model data and indicates the texture after adjustment. Furthermore, if coloring is not performed and only one color is applied to each position on the surface of the model, then in step S102, for example, 3D model data that does not include a texture for the surface color and includes shape data may be acquired. In this case, for example, the texture for adjusting the texture may be used as is as the texture for modeling. With this configuration, for example, a texture for modeling that shows the texture after adjustment may be appropriately generated.

In addition, when generating an actual texture for adjusting texture, the number of tones restricted by the tones number restriction and the amount of correction by gamma correction may be selected based on the desired texture. More specifically, for example, when expressing a texture with a higher perceived translucency, the number of tones restricted by the tones number restriction and the amount of correction by gamma correction may be selected to maximize the translucency. However, the optimal values for the number of tones and the amount of correction may vary depending on the shape of the shaped object. Therefore, when generating a texture for adjusting texture, for example, the number of tones restricted by the tones number restriction and the amount of correction by gamma correction may be used as parameters, and the conditions specified by these parameters may be made different to create (generate) multiple types of textures. In this case, for example, a rendering image showing the state in which each texture is applied to the three-dimensional shape indicated by the shape data is generated. Then, for these rendering images, a preselected index on an image basis is calculated, and a texture to be used as a texture for adjusting texture is selected based on the result. With this configuration, for example, it is possible to select a texture based on an index selected based on a desired texture.

More specifically, for example, when considering translucency as texture, as explained above, the texture perceived by the observer changes depending on the contrast in the non-specular area and the covariance of the normal direction and the shadow. Therefore, in this case, for example, it is possible to select a texture using an index related to the contrast in the non-specular area (hereinafter referred to as index 1) and an index related to the covariance of the normal direction and the shadow (hereinafter referred to as index 2). In addition, in this case, for an object with high translucency, for example, the shadow is weakened by transportation under the surface, and the contrast is reduced. Therefore, when trying to increase the translucency in the apparent texture, for example, it is possible to use a texture adjustment texture with low contrast. In this case, it is possible to calculate the contrast for the area (object area) corresponding to the shaped object in the rendering image corresponding to each of the multiple textures to be selected, and select the texture with the lowest contrast. In this way, for example, it is possible to appropriately increase the translucency perceived by the observer. In addition, in this case, it is possible to calculate the contrast using a known method such as Michelson contrast. In this case, for example, each texture is used as the original image for which contrast is to be calculated, and the results calculated for the luminance values (pixel values) of the original image and various spatial frequency subbands (for example, about nine types of subbands) are averaged. Then, for example, the texture with the smallest average value is selected.

In addition, with regard to index 2, for an object with high translucency, for example, it is considered that the consistency between the shape and the shading distribution is lost. Therefore, when trying to increase the translucency in the apparent texture, it is considered to use a texture adjustment texture that reduces the consistency between the shape and the shading distribution. In this case, for example, it is considered to calculate how much the surface luminance pattern changes for the object area in the rendering image corresponding to each of the multiple textures to be selected compared to the opaque case, and to select the texture that causes the largest change. In this way, for example, it is possible to appropriately increase the translucency perceived by the observer. More specifically, in this case, for example, in addition to the rendering images corresponding to each of the multiple textures to be selected, it is considered to use a rendering image corresponding to the opaque case. As the rendering image corresponding to the opaque case, for example, it is considered to generate a rendering image showing a state in which no texture is applied to the three-dimensional shape indicated by the shape data. In addition, in this case, for the object area in each rendering image, for example, the median value of the pixel value in the image is used as a criterion, and the surface luminance pattern is coded. Then, for the rendering images corresponding to each of the multiple textures to be selected, the number of pixels with different signs is counted compared to the rendering image corresponding to the opaque case, and the texture with the largest number of pixels with different signs is selected. In this way, for example, it is possible to appropriately select a texture to be used as a texture for texture adjustment based on multiple pre-selected indices. Also, depending on the shape of the shaped object, for example, it is possible that the optimal texture differs depending on the indices. In this case, for example, it is possible to select a texture by prioritizing the results of one of the indices based on a preset criterion.

In this way, in this example, for example, a texture for adjusting texture can be appropriately generated based on an AO texture that indicates the shadows that are generated on the surface of the model due to ambient light. In addition, by determining the color to be applied to each position on the surface of the model based on the texture for adjusting texture, the observer can visually recognize the state of the model as if the shadows are generated in a state different from the original shadows. This also makes it possible to change the texture perceived by the observer, for example, of the texture of translucency. Therefore, according to this example, for example, a model that expresses a variety of textures can be appropriately formed. This also makes it possible to more appropriately perform, for example, modeling with a desired texture or modeling a model with a high design quality.

Here, in this example, the operation of determining the color to be applied to each position on the surface of the object based on the texture for adjusting the texture can be considered to be, for example, an operation of generating a texture different from the texture perceived in a model in which the color at each position on the surface is uniform. More specifically, for example, if the texture perceived by the observer due to the influence of the shadow generated on the surface of the object by the light (e.g., ambient light) irradiated to the object is defined as the perceived texture, and the perceived texture perceived in a model in which the color at each position on the surface is uniform is defined as the uniform color texture, the operation of determining the color to be applied to each position on the surface of the object based on the texture for adjusting the texture can be considered to be, for example, an operation of determining the color to be applied to each position on the surface of the object so that the observer perceives a perceived texture different from the uniform color texture. By configuring in this way, for example, the texture perceived by the observer of the object can be appropriately changed. Also, as can be understood from the above explanation, for example, a texture related to translucency can be used as the perceived texture. In this case, in the operation of determining the color to be applied to each position on the surface of the shaped object based on the texture for adjusting the texture, the color to be applied to each position on the surface of the shaped object is determined so that, for example, the perceived texture is different from the uniform color texture, and at least a portion of the shaped object is perceived as being more translucent. With this configuration, for example, it is possible to appropriately express high translucency as the texture of the shaped object.

In addition, the operation of generating the modeling data in the control PC 14 is not limited to the operation described above, and can be modified in various ways. For example, in the above, the operation of generating the texture for texture adjustment has been described mainly in terms of a method of using an AO texture as shading data. In this case, for example, the occlusion degree information can be automatically obtained, so that the creation of the texture for texture adjustment can be easily and appropriately automated. In contrast, in a modified example of the operation of generating the texture for texture adjustment, the shading data may be obtained by, for example, a computer simulation of a method other than the AO method. In this case, for example, a rendering image showing a state in which light is irradiated under desired light source conditions to a shape indicated by the shape data included in the 3D model data is generated, and the shading data is obtained based on the rendering image. Depending on the quality required for modeling, for example, the shading data may be generated by a method of manually determining and designing the brightness required for each part in the CG data. In these cases, it is also possible to generate a texture to be pasted on the surface of the three-dimensional shape indicated by the shape data as the shading data. In this case, it is possible to generate a texture for adjusting the texture by using this texture instead of the AO texture and appropriately performing the same or similar processing as when using the AO texture. In a further modified example of the operation for generating a texture for adjusting the texture, the shading data may be obtained, for example, by actually performing measurements rather than by computer simulation. In this case, it is possible to generate a texture for adjusting the texture, for example, by the operation shown in FIG. 5.

Figure 5 is a flowchart showing a further modified operation of generating texture for texture adjustment, showing a modified operation of step S104 in the flowchart shown in Figure 3 (a). In this modified example, when generating texture for texture adjustment, a measurement object is created to obtain shading data. More specifically, in this case, for example, a measurement object is created (S212) that is a measurement object used to obtain shading data based on shape data included in the 3D model data obtained in step S102. The measurement object may be created, for example, using the modeling device 12 (see Figure 1). In this case, the measurement object may be considered, for example, as a model that is an intermediate product separate from the product to be modeled as the final product.

The measurement object may be, for example, a three-dimensional object having the same shape as the object to be formed as the final product. The measurement object may be, for example, created to be the same size as the object to be formed. This configuration can more appropriately generate the same shadows as those that occur according to the shape of the object. Depending on the accuracy required for the measurement, the measurement object may be created to be a different size from the object to be formed. In this case, it is possible to create a measurement object that is smaller than the object to be formed. This configuration can appropriately reduce the time and cost required to create the measurement object. The measurement object may be created by a method other than forming using the forming device 12. In this case, the measurement object may be, for example, a three-dimensional object having the same shape as the object to be formed and made of a different material.

In addition, in this modified example, after the measurement object is created, light is irradiated onto the measurement object to generate a shadow on the surface of the measurement object, and the result is measured (S214). Also, based on this measurement result, shading data is acquired. With this configuration, for example, shading data can be acquired appropriately with high accuracy by actual measurement. More specifically, in this case, for example, an image showing a shadow is acquired by photographing the measurement object in a state where light is irradiated. Then, shading data is acquired based on this image. Also, after the shading data is acquired, a texture for texture adjustment is generated based on the shading data in a computer such as the control PC 14 (see FIG. 1) (S216). In this case, the process of generating a texture for texture adjustment based on the shading data can be performed in the same or similar manner as, for example, when an AO texture is used. More specifically, in this case, in step S214, it is considered that a texture to be pasted on the surface of the three-dimensional shape indicated by the shape data is generated as shading data. With this configuration, the shading data in this modified example can be treated in the same or similar manner as, for example, an AO texture. This also allows the operation of generating texture for texture adjustment in step S216 to be performed in the same or similar manner as when using AO textures.

In this modified example, for example, a texture for adjusting texture can be appropriately generated. This can also appropriately change the apparent texture of the shaped object. In this case, by changing the light source conditions for irradiating the measurement three-dimensional object with light in step S214, shading data can be appropriately acquired with high accuracy in accordance with various light source conditions. In a further modified example of the operation for generating texture for adjusting texture, the shading data may be acquired in a format other than texture. In this case, in step S216, the texture for adjusting texture is generated based on the shading data in a format other than texture.

In addition, in a further modified example of the operation of generating texture for texture adjustment, for example, it is possible to obtain shading data based on the results of measurements performed using an existing three-dimensional object without creating a measurement three-dimensional object. More specifically, it is possible to create data indicating an existing three-dimensional object, such as a building (architecture) or object that exists before the creation of the modeling data is started, as the modeling data. In such a case, it is possible to obtain shading data by using an existing three-dimensional object without separately creating a measurement three-dimensional object. In this case, in the operation of obtaining shading data, for example, shading data is obtained based on the shading generated on the surface of the existing three-dimensional object. In this case, for example, the operation of step S212 in the flowchart shown in FIG. 5 is omitted, and an existing three-dimensional object is used instead of the measurement three-dimensional object, and the shading data is obtained by performing the same or similar operation as the operation of step S214 and thereafter. In addition, a texture for texture adjustment is generated based on the shading data obtained in this way. Even in this configuration, for example, shading data can be obtained appropriately with high accuracy. In addition, for example, a texture for texture adjustment can be generated appropriately.

As for the modeling data, it is also possible to create data representing a model smaller than an existing three-dimensional object, such as a miniature. In this case, the operation of acquiring shadow data using an existing three-dimensional object can also be considered as, for example, an operation of acquiring shadow data using a three-dimensional object larger than the model to be modeled. As for the existing three-dimensional object, as described above, it is also possible to use a particularly large three-dimensional object, such as a building. In this case, it may be very costly to irradiate the three-dimensional object with light using a lighting device or the like. Therefore, in such a case, the shadow data may be acquired based on the shadows that are generated on the surface of the three-dimensional object by natural light such as sunlight. With this configuration, it is possible to appropriately acquire shadow data that represents the shadows that are generated on the surface of the three-dimensional object under light source conditions corresponding to natural light, for example.

In the above, the explanation has been mainly on changing the apparent texture of a molded object using a texture adjustment texture. However, depending on the configuration of the molded object, it is also possible to change the actual texture of the molded object by using a partial region of the molded object. In this case, the texture perceived by the observer can be changed more appropriately by changing the actual texture of the object while changing the apparent texture of the object using a texture adjustment texture. In this case, it is also possible to form an object having a scattering region 156 (see FIG. 2), for example, as in the modified example explained above with reference to FIG. 2(b). More specifically, in this case, it is possible to use a scattering region 156 having the configuration shown in FIG. 6, for example.

6 is a diagram for explaining a modified example of the object 50 in more detail, and shows an example of the configuration of the scattering region 156 when forming the object 50 having the scattering region 156. FIG. 6(a) is a diagram showing an example of the configuration of the object 50 having the scattering region 156, and shows an example of the detailed configuration of the scattering region 156 in the object 50 shown in FIG. 2(b) together with the light reflecting region 152 and the colored region 154. In addition, in FIG. 6(a), for convenience of illustration, the overlapping manner of the regions in the normal direction perpendicular to the surface of the object 50 is simplified for a part of the object 50. In this modified example, the object 50 has the light reflecting region 152, the scattering region 156, and the colored region 154. The scattering region 156 is a region formed using white ink and clear ink, and is formed between the light reflecting region 152 and the colored region 154. In this case, as described above, the color material contained in the white ink can be considered as an example of a scatterer. In addition, in this modified example, the scattering region 156 is a region in which the amount of scatterers contained per unit volume varies depending on the position by varying the proportion of white ink used. In this case, the proportion of white ink used can be considered, for example, as the ratio of white ink used per unit volume when forming the scattering region 156. This ratio can also be considered, for example, as the ratio of the amount of white ink used to the total amount of white ink used and the amount of clear ink used.

More specifically, in this modified example, the scattering region 156 has a plurality of regions 162a-e in which the proportion of white ink used is different from one another. Each of the plurality of regions 162a-e is a region in which the position in a plane parallel to the surface of the model 50 is different from one another, and is formed using white ink and clear ink. In this case, some of the plurality of regions 162a-e may be formed using only white ink or only clear ink. In this configuration, by forming the scattering region 156 using white ink and clear ink, for example, in the scattering region 156 below the colored region 154, it is possible to scatter light so as to show translucency. In addition, this makes it possible to appropriately change, for example, the actual texture of the model 50. Therefore, according to this modified example, for example, it is possible to appropriately combine changing the apparent texture of the model using a texture adjustment texture and changing the actual texture of the model 50 by using the scattering region 156. In this case, by using a different proportion of white ink in each of the multiple regions 162a-e, differences occur in the way that light incident from the outside through the colored region 154 is scattered. As a result, differences in texture occur in the positions of the colored region 154 that overlap with each of the multiple regions 162a-e. Therefore, according to this modified example, it is possible to, for example, provide a more diverse range of textures that the observer perceives for the model 50.

In addition, in this modified example, the texture perceived by the observer can be considered to be generated by combining, for example, the effect of using the texture adjustment texture and the effect of using the scattering region 156 having the regions 162a-e. In this case, in order to change the texture more appropriately, for example, the positions at which the multiple regions 162a-e are formed can be formed to match the image indicated by the texture adjustment texture. In addition, as a method for doing so, the method for forming the scattering region 156 can be determined, for example, based on shading data such as an AO texture. More specifically, in this case, in the operation of generating the modeling data in the control PC 14 or the like, the proportion of white ink used for each position of the scattering region 156 is determined, for example, based on shading data. With this configuration, for example, modeling data indicating the modeled object 50 having the above-mentioned scattering region 156 can be appropriately generated. In addition, in this case, the determination of the proportion of white ink used for each position of the scattering region 156 can be considered to be, for example, the amount of scatterer contained per unit volume at each position of the scattering region 156.

In the case of the model 50 of this modified example, the light reflection region 152 formed using white ink can also be considered as a region that scatters light. In this regard, in this modified example, the light reflection region 152 can be considered to have a constant ratio of white ink used at each position, unlike the scattering region 156. As a result, the light reflection region 152 can be considered to be a region that uniformly scatters light, unlike the scattering region 156. More specifically, the light reflection region 152 can be considered to be formed using only white ink, for example. The light reflection region 152 can also be considered to be a region formed using an amount of white ink that makes the region opaque, for example. In a further modified example of the configuration of the model 50, the light reflection region 152 may be formed using white ink and clear ink. In this case, the light reflection region 152 can also be considered to have a constant ratio of white ink used at each position, for example. In a further modification of the configuration of the model 50, the proportion of white ink used at each position in the scattering region 156 can also be kept constant. In this case, the scattering region 156 can be considered to be, for example, a region in which white ink is used at a lower proportion than in the light reflecting region 152.

In addition, in a further modified example of the configuration of the model 50, for example, as shown in FIG. 6B, it is also possible to form a scattering region 156 having multiple layers 172. FIG. 6B is a diagram showing another example of the configuration of the model 50 having the scattering region 156, and shows a simplified view of how the regions overlap in the normal direction perpendicular to the surface of the model 50 for a part of the model 50. In this modified example, the scattering region 156 has multiple layers 172 that overlap in the normal direction of the model 50. In this case, each layer 172 can be considered to be, for example, a layered region that spreads along the surface shape of the model 50. In this modified example, each layer 172 is formed using white ink and clear ink. In this case, each layer 172 can be considered to be, for example, a translucent region formed by using less white ink per unit volume than the light reflecting region 152.

In addition, it is possible to form each of the multiple layers 172 in the scattering region 156 with a different ratio of white ink used. In this case, the scattering region 156 can be considered to have a configuration in which multiple layers 172 with different ways of scattering light overlap in the normal direction of the model 50. By forming the scattering region 156 with such a configuration, for example, it is possible to change the way light is scattered in the scattering region 156 in various ways. This also makes it possible to change the texture of the model 50 in a more diverse way. In this case, it is also possible to form the multiple layers 172 by gradually changing the ratio of white ink used according to the order in which they overlap in the normal direction. In this case, the scattering region 156 can be considered to be a region in which the characteristics change in a gradational manner, for example, for each layer 172. By configuring it in this way, for example, a more diverse texture can be expressed in the model 50. More specifically, in this case, for example, it is possible to use the largest proportion of white ink in the layer 172 closest to the light reflecting region 152, and gradually decrease the proportion of white ink as it moves away from the light reflecting region 152. Conversely, for example, it is also possible to use the smallest proportion of white ink in the layer 172 closest to the light reflecting region 152, and gradually increase the proportion of white ink as it moves away from the light reflecting region 152. In addition, at least some of the layers 172 of the multiple layers 172 in the scattering region 156 may be formed to have multiple regions 162, such as the scattering region 156 shown in FIG. 6A. With this configuration, for example, a more diverse texture can be expressed in the shaped object 50.

Next, supplementary explanations will be given regarding each of the configurations described above. In the following, for convenience of explanation, the present example will include the modified examples described above. In the field of 3D modeling (3D printing), if a configuration that actually changes the physical characteristics of the scattering phenomenon, such as the configuration using the scattering region 156 described above, is used, it is possible to express the texture of translucency, etc. However, in this case, the range of textures that can be expressed may be narrowed depending on the characteristics of the material used for modeling, etc. In response to this, the inventor of the present application focused on the fact that the factors by which humans perceive textures such as translucency do not necessarily depend on physical phenomena (scattering phenomena, etc.). Based on this viewpoint, the inventor considered changing the apparent texture of a modeled object using a texture adjustment texture in which pixel values (brightness values) are controlled in accordance with the clues for perceiving the texture. In this case, the texture adjustment texture can be considered to be created with the concept of reproducing the clues by which humans perceive textures such as translucency, for example.

In this case, the method used in this example can be considered to change the texture perceived by the observer in an optical illusion, for example, by reproducing the texture-related features with texture. More specifically, in this case, for example, for a model formed with a configuration that does not actually produce scattering that indicates translucency, the features related to the perception of translucency are reproduced with a texture for adjusting the texture, thereby expressing apparent translucency. With this configuration, translucency can be appropriately expressed even if a region for changing the physical scattering state (scattering region 156) is not formed, for example, as in the model with the configuration shown in FIG. 2(a). In this case, if the scattering region 156 is further used, for example, as in the model with the configuration shown in FIG. 2(b), the translucency can be further increased. In this case, for example, by using the scattering region 156 that scatters differently depending on the position, it is possible to express a special appearance, etc.

The inventors of the present application also conducted evaluation experiments to confirm that the texture perceived by the observer changes as a result of the method described above. More specifically, the inventors of the present application created objects under a variety of conditions by combining multiple different types of shapes with multiple different types of texture-adjusting textures. Then, by evaluating the state of each object using a subjective evaluation method involving the participation of multiple subjects, the inventors confirmed that significant changes occur in textures such as translucency due to the influence of the texture-adjusting textures.

The present invention can be suitably used, for example, in a method for creating modeling data.

10: Modeling system, 102: Head unit, 104: Modeling table, 106: Scanning drive unit, 110: Control unit, 12: Modeling device, 14: Control PC, 152: Light reflection area, 154: Coloring area, 156: Scattering area, 162: Area, 172: Layer, 202: Inkjet head, 204: Ultraviolet light source, 206: Flattening roller, 50: Modeled object, 52: Support layer

Claims (13)

A method for creating modeling data that is data representing a modeled object to be modeled by a modeling device, comprising the steps of:
A shape determination step of determining a shape of the object;
a shadow data acquiring step of acquiring shadow data representing a shadow generated on a surface of the object according to a shape of the object;
and a surface color determination step of determining a color to be applied to each position on the surface of the object based on the shading data. In the shadow data acquisition step, a shadow image is acquired as the shadow data, which is an image showing a shadow occurring on a surface of the object;
2. The method for creating modeling data according to claim 1, wherein in the surface color determination step, a color to be applied to each position on the surface of the model is determined based on an inverted image which is an image obtained by performing gradation inversion on the shaded image. The method for creating modeling data according to claim 2, characterized in that in the surface color determination step, a color to be applied to each position on the surface of the model is determined based on the inverted image so that the effect of shading on the surface of the model according to the shape of the model is reduced and perceived by an observer. When the perceived texture is defined as the texture perceived by an observer due to the influence of shadows generated on the surface of the object by light irradiated onto the object, and the perceived texture perceived in the object in which the color of each position on the surface is made uniform is defined as the uniform color texture,
The method for creating modeling data according to claim 1 , wherein in the surface color determination step, a color to be applied to each position on the surface of the model is determined so that the perceived texture different from the uniform color texture is perceived by an observer. The perceived texture is a texture related to translucency,
The method for creating modeling data according to claim 4, characterized in that, in the surface color determination step, a color to be applied to each position on the surface of the model is determined so that the perceived texture is different from the uniform color texture, thereby causing at least a portion of the model to be perceived as more translucent. In the shape determination step, a shape of the object is determined based on shape data which is data indicating a shape of the object;
2. The method according to claim 1, wherein in the surface color determination step, a texture is generated to be applied to a surface of the three-dimensional shape represented by the shape data. a modeling data generating step of generating the modeling data based on the shape data and the texture,
The method for creating modeling data according to claim 6, characterized in that, in the modeling data generation step, the modeling data is generated which indicates the modeled object having a scattering region which is a region containing a scatterer that is an inclusion that has the property of scattering light and in which the amount of the scatterer contained per unit volume varies depending on the position. The method for creating modeling data according to claim 7, characterized in that in the modeling data generation step, the amount of the scatterer contained per unit volume at each position of the scattering region is determined based on the shading data, thereby generating the modeling data representing the model having the scattering region. The method for creating modeling data according to any one of claims 1 to 8, characterized in that in the shadow data acquisition step, the shadow data is acquired by computer simulation using the AO method (ambient occlusion method). The method for creating modeling data according to any one of claims 1 to 8, characterized in that in the shadow data acquisition step, a three-dimensional object having the same shape as the shape determined in the shape determination step is created, and the shadow data is acquired based on a shadow generated on the surface of the three-dimensional object by irradiating the three-dimensional object with light. The modeling data is data representing an existing three-dimensional object,
9. The method for generating modeling data according to claim 1, wherein, in the shadow data obtaining step, the shadow data is obtained based on a shadow occurring on a surface of the existing three-dimensional object. A modeling data generating device that generates modeling data which is data representing a model to be modeled by a modeling device,
A shape determination process for determining a shape of the object;
a shadow data acquisition process for acquiring shadow data which is data indicating a shadow generated on a surface of the object according to a shape of the object;
and a surface color determination process for determining a color to be applied to each position on the surface of the object based on the shading data, thereby generating the object data. A modeling apparatus for modeling a modeled object, comprising:
The modeling data generating apparatus according to claim 12,
and a modeling device that models the object based on the modeling data generated by the modeling data generation device.

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