Image-processing device, image-processing method, and image-processing program

Abstract

An image processing device (100) comprises: a shape information analysis unit (14) that calculates the geometric shape of an object surface including a normal distribution on the object surface, and calculates the roughness of the object surface on the basis of the normal distribution; a basic light beam setting unit (18A) that, in accordance with the roughness of the object surface, sets the radiation position of a basic light beam related to rendering of the object, the angle of the basic light beam with respect to the object surface, the light distribution of the basic light beam, and the radiance of the basic light beam; a virtual camera setting unit (20) that sets the position of the virtual camera in accordance with the roughness of the object surface; and a display image generation unit (22) that generates an image representing the surface shape of the object on the basis of the geometric shape of the object surface including the normal distribution on the object surface.

Description

Image processing device, image processing method, and image processing program

[0001] The present disclosure relates to an image processing device, an image processing method, and an image processing program.

[0002] In recent years, the use of machining simulators that simulate the shape and surface texture of the machining result based on parameters set in the machining machine before machining with the machine has been increasing. However, machining using NC (numerical control) machining programs such as G-code created in CAM (computer-aided manufacturing) systems can sometimes result in machining defects that result in a finished product that differs from the intention of the machining designer. Causes of machining defects include, for example, problems with the prepared machining program itself, or inappropriate adjustments to the machining conditions or machine tool that cause the machine tool to not follow the instructions of the machining program. In the case of cutting, particularly when there is a problem with the machining program, machining defects often manifest as uncut or overcutting.

[0003] Typically, before machining the desired part, a set of NC machining instructions is tested by machining a test workpiece formed from a softer, less expensive material. If visual inspection of the test workpiece reveals undesirable non-conformance of the test workpiece with the desired shape, the NC machining instructions can be modified. However, such manual testing is time-consuming and costly. For example, the time to machine a single test workpiece may require several hours, and several iterations may be required before an acceptable set of NC machining instructions is obtained. Therefore, it is desirable to test the test workpiece for non-conformance with the desired shape through computer-based simulation and rendering.

[0004] However, when rendering surface shapes made of metal, the metal's reflection can be too directional, resulting in blown-out highlights, or the use of an inappropriate environment map can cause the metal surface to reflect, making it difficult to see fine surface shapes such as hairlines or matte finishes.

[0005] Patent document 1 discloses an invention of an image processing device, an image processing method, and a program that calculates the angle between the normal of each polygon of the surface shape that makes up an object and a light vector, and increases the brightness of the texture the closer it is to 0 degrees (i.e., the closer the angle), thereby making it easier to see the facial expressions of characters placed in a virtual space.

[0006] JP 2009-140237 A

[0007] However, in the invention described in Patent Document 1, since characters have a front, the character can be displayed with good visibility by determining the angle of the light vector with respect to a specific normal direction and determining the texture brightness, but the machined surface does not have a front, and the machined surface characteristics cannot be displayed with good visibility unless the lighting parameters are optimized based on the characteristics of the machined surface.In addition, since metal has high directional reflection, there is a problem that the machined workpiece cannot be displayed with good visibility if inappropriate lighting parameters or environment maps are used.

[0008] An object of the present disclosure is to provide an image processing device, an image processing method, and an image processing program that are capable of generating an image taking into account the state of light rays on an object.

[0009] The image processing device of the present disclosure includes a shape information analysis unit that calculates the geometric shape of the surface of the object including the normal distribution on the surface of the object and calculates the surface roughness of the object based on the normal distribution; a basic ray setting unit that sets the emission position of a basic ray related to rendering of the object, the angle of the basic ray with respect to the surface of the object, the luminous intensity distribution of the basic ray, and the radiance of the basic ray according to the surface roughness of the object calculated based on the normal distribution; a virtual camera setting unit that sets the position of a virtual camera observing the object according to the surface roughness of the object; and a display image generation unit that generates an image representing the surface shape of the object based on the geometric shape of the surface of the object including the normal distribution on the surface of the object.

[0010] The image processing method of the present disclosure is an image processing method executed by a computer, and includes the steps of: calculating a geometric shape of an object's surface including a normal distribution on the object's surface; calculating the roughness of the object's surface based on the normal distribution; setting the emission position of a basic ray related to rendering of the object, the angle of the basic ray with respect to the object's surface, the luminous intensity distribution of the basic ray, and the radiance of the basic ray according to the roughness of the object's surface calculated based on the normal distribution; setting the position of a virtual camera observing the object according to the roughness of the object's surface; and generating an image representing the surface shape of the object based on the geometric shape of the object's surface including the normal distribution on the object's surface.

[0011] The image processing program of the present disclosure causes a computer to execute the steps of: calculating the geometric shape of the surface of the object, including the normal distribution on the surface of the object; calculating the surface roughness of the object based on the normal distribution; setting the emission position of a basic ray related to rendering of the object, the angle of the basic ray with respect to the surface of the object, the luminous intensity distribution of the basic ray, and the radiance of the basic ray, according to the surface roughness of the object calculated based on the normal distribution; setting the position of a virtual camera observing the object, according to the surface roughness of the object; and generating an image representing the surface shape of the object, based on the geometric shape of the surface of the object, including the normal distribution on the surface of the object.

[0012] According to the present disclosure, it is possible to provide an image processing device, an image processing method, and an image processing program that are capable of generating an image taking into account the state of light rays on an object.

[0013] FIG. 1 is a schematic diagram showing an example of the configuration of an image processing device according to embodiment 1. FIG. 2 is a block diagram showing an example of the configuration of a processing system that processes a workpiece related to a display image generated by the image processing device according to embodiment 1. FIG. 3 is a block diagram showing an example of the hardware configuration of a control unit according to embodiment 1. FIG. 4 is a flowchart showing an example of processing by the image processing device according to embodiment 1. FIG. 5 is an explanatory diagram showing an example of the position of lighting when the workpiece surface has rough texture. FIG. 6 is an explanatory diagram showing an example of the position of lighting when the workpiece surface has smooth texture. FIG. 7 is an explanatory diagram showing an example of the position of lighting and the position of a virtual camera in embodiment 2.

[0014] An image processing device, an image processing method, and an image processing program according to embodiments will be described below with reference to the drawings. The following embodiments are merely examples, and the embodiments can be combined as appropriate and each embodiment can be modified as appropriate.

[0015] 1 is a schematic diagram showing an example of the configuration of an image processing device 100 according to embodiment 1. As shown in Fig. 1, the image processing device 100 includes a shape data input unit 12 to which shape data of an object, that is, shape data of a workpiece processed by a machine tool, a control unit 10 that generates three-dimensional CG (Computer Graphics) by rendering the shape data received from the shape data input unit 12, and a display unit 24 that displays the generated three-dimensional CG.

[0016] The shape data input unit 12 receives input of information indicating the shape of the workpiece surface, information on the workpiece surface texture, etc. The information indicating the shape of the workpiece surface is, for example, two-dimensional or three-dimensional CAD (Computer-Aided Design) data, coordinate values ​​of the surfaces that make up the workpiece, or G-code, which is an NC machining command output by a CAM device described below. The information on the workpiece surface texture is, for example, information on the material and surface treatment of the workpiece surface. More specifically, the information on the material of the workpiece surface is information indicating aluminum, iron, copper, stainless steel, chromium, titanium, synthetic resin, or the like. Furthermore, the information on the surface treatment is, more specifically, information indicating a mirror finish, hairline, matte finish, or the like.

[0017] The control unit 10 includes a shape information analysis unit 14 that analyzes information indicating the shape of the surface of the workpiece input to the shape data input unit 12; a material information setting unit 16 that sets the material of the workpiece based on information related to the texture of the surface of the workpiece input to the shape data input unit 12; an illumination condition setting unit 18 that sets the illumination conditions for the workpiece; a virtual camera setting unit 20 that sets the position of a virtual camera (hereinafter referred to as a "virtual camera"), assuming that the 3D CG of the workpiece is an image captured by the virtual camera; and a display image generation unit 22 that generates the 3D CG of the workpiece based on the material of the workpiece set by the material information setting unit 16, the illumination conditions set by the illumination condition setting unit 18, and the position of the virtual camera set by the virtual camera setting unit 20.

[0018] The display image generation unit 22 outputs the generated 3D CG to the display unit 24. The display unit 24 is, for example, a monitor such as a liquid crystal display, an organic electroluminescence (EL) display, a micro light-emitting diode (LED) display, or a cathode ray tube (CRT). The display unit 24 may also be an aerial display, a head-mounted display (HMD), a virtual reality (VR) device, an augmented reality (AR) device, a tablet terminal, a smartphone, or a television.

[0019] The shape information analysis unit 14 calculates a normal distribution function for a portion or the entire region of the workpiece based on, for example, shape information about the workpiece surface. For example, the Microfacet model assumes that the complex reflection patterns on the workpiece surface are caused by the distribution of minute normals on the workpiece surface. The normal distribution function is a probability distribution function that indicates the existence of such normal vectors. In the first embodiment, the roughness of the workpiece surface is determined by sampling the distribution of normal vectors, which is the calculation result of the normal distribution function. The normal distribution function is often a distribution function called the Beckmann distribution shown in the following equation (1). In the following equation (1), m is the average slope of the minute faces on the object surface, and α is the angle between the normal vector of the minute face on the object surface and the intermediate vector obtained by adding the vector from the object surface to the light source and the vector from the object surface in the line of sight (virtual camera direction).

[0020]

[0021] In the first embodiment, for example, if the value calculated by the above formula (1) is less than a predetermined threshold (for example, 0.1), the surface is determined to be smooth, and if it is equal to or greater than the predetermined threshold, the surface is determined to be rough. In addition to the Beckmann distribution shown in formula (1), a distribution function such as GGX (Trowbridge-Retiz) may also be used.

[0022] The illumination condition setting unit 18 sets the illumination radiation position and angle, as well as the illumination radiance, in conjunction with the coordinate position and line of sight direction of the virtual camera, based on the calculation result of the normal distribution function by the shape information analysis unit 14. The illumination condition setting unit 18 includes a basic ray setting unit 18A that sets a basic ray emitted from a virtually provided main light source onto the workpiece.

[0023] The basic light ray setting unit 18A sets the position, intensity, direction, and light distribution of the lighting that illuminates the displayed workpiece, as well as an environmental map of the workpiece surroundings. For example, the basic light ray setting unit 18A sets the illumination range of the lighting in conjunction with the viewpoint position of the virtual camera, and sets the light ray position of the basic light ray.

[0024] Specifically, when the basic ray setting unit 18A determines that the surface texture of the workpiece is rough based on the calculation result of the normal distribution function by the shape information analysis unit 14, it sets the light distribution of the illumination to a wide light distribution, thereby brightening the reflected light from the workpiece surface as a whole. Furthermore, when the basic ray setting unit 18A determines that the surface texture of the workpiece is smooth based on the calculation result of the normal distribution function by the shape information analysis unit 14, it sets the light distribution of the illumination to a narrow light distribution.

[0025] The virtual camera setting unit 20 sets the position of the virtual camera by setting the viewpoint position, line of sight direction, and field of view for observing the displayed workpiece.

[0026] The display image generation unit 22 generates a display image by performing rendering based on the information input from the shape data input unit 12 and the information set by the virtual camera setting unit 20, the material information setting unit 16, and the basic ray setting unit 18A in the lighting condition setting unit 18. The display image generation unit 22 performs rendering using, for example, a path tracing method based on basic rays. Specifically, the display image generation unit 22 generates a realistic display image (3D CG) by calculating the appearance based on repeated reflections of basic rays on the workpiece surface. The display image generation unit 22 outputs the generated display image to the display unit 24, and the display unit 24 displays the display image.

[0027] 2 is a block diagram schematically showing the configuration of a machining system 1 that machines a workpiece related to a display image generated by the image processing device 100 according to Embodiment 1. As shown in FIG. 1, the machining system 1 includes a machining simulation device 400, a CAM device 200, and an NC machine tool 300.

[0028] The CAM device 200 creates a machining program such as a G-code in which operation commands to the NC machine tool 300 are written.

[0029] The machining simulation device 400 is a device that simulates, based on three-dimensional CG, the machining of a workpiece by the NC machine tool 300, on the basis of the machining program generated by the CAM device 200. In the first embodiment, the image processing device 100 may be included in the machining simulation device 400.

[0030] NC machine tool 300 machines a workpiece based on a machining program created by CAM device 200. In the example shown in FIG. 2 , NC machine tool 300 has a ball-end milling cutter 301 as a cutting tool and a drive unit 302 that drives ball-end milling cutter 301. Ball-end milling cutter 301 is capable of forming the surface of a workpiece into a free shape. Drive unit 302 has, for example, a motor and a transmission mechanism (e.g., gears) that transmits the driving force of the motor to ball-end milling cutter 301. Note that NC machine tool 300 is not limited to a ball-end milling cutter, and may have other tools such as a drill.

[0031] 3 is a block diagram showing an example of a hardware configuration of the control unit 10 according to embodiment 1. As shown in Fig. 3, the control unit 10 is configured by a computer in which a CPU (Central Processing Unit) 31, which is a computing element (processor), a main memory 32, an input / output interface (I / O interface) 33, and a memory unit 34 are each connected to a system bus 35. The control unit 10 may be configured by a plurality of computers connected via a network, or may be configured by a processing circuit.

[0032] The CPU 31 is an integrated circuit (IC) that performs arithmetic processing. In addition to the CPU 31, a computing element such as a digital signal processor (DSP), a graphics processing unit (GPU), a network processor, or a field programmable gate array (FPGA) may be used. By executing the image processing program according to the first embodiment, the CPU 31 realizes an image processing method having a shape information analysis function that analyzes information indicating the shape of the surface of the workpiece input to the shape data input unit 12, a material information setting function that sets the material of the workpiece based on information related to the texture of the surface of the workpiece input to the shape data input unit 12, an illumination condition setting function that sets the illumination conditions for the workpiece, a virtual camera setting function that sets the position of a virtual camera, and a display image generation function that generates a 3D CG image of the workpiece based on the material of the workpiece, the illumination conditions, and the position of the virtual camera. As a result, by executing the image processing program, the CPU 31 functions as a shape information analysis unit 14, a material information setting unit 16, an illumination condition setting unit 18, a virtual camera setting unit 20, and a display image generation unit 22. The image processing program is provided, for example, on a recording medium on which it is recorded.

[0033] The main memory 32 is configured by a volatile storage device such as a RAM (Random Access Memory) or a non-volatile storage device such as a ROM (Read Only Memory). The storage unit 34 is configured by a non-volatile storage device such as a HDD (Hard Disk Drive) or a flash memory.

[0034] The I / O interface 33 is a port to which the shape data input unit 12, the display unit 24, etc. are connected.

[0035] 4 is a flowchart showing an example of processing by the image processing device 100 according to Embodiment 1. In step S001, shape data is input to the shape data input unit 12, and the image processing device 100 acquires the shape data.

[0036] In step S002, the shape information analysis unit 14 of the control unit 10 calculates normal distribution information of the shape data.

[0037] In step S003, the shape information analysis unit 14 of the control unit 10 determines whether the value calculated by the above formula (1) is 0.1 or more and whether the surface shape of the workpiece is rough. If the surface shape of the workpiece is rough in step S003, the procedure proceeds to step S004, and if the surface shape of the workpiece is not rough, the procedure proceeds to step S006.

[0038] In step S004, if the shape information analysis unit of the control unit 10 determines that the properties of the work surface are rough, for example, based on normal distribution information, the basic ray setting unit 18A in the illumination condition setting unit 18 of the control unit 10 sets the light distribution of the illumination to a first light distribution indicating a wide light distribution, thereby brightening the reflected light from the object surface overall.

[0039] In step S005, if the shape information analysis unit of the control unit 10 determines that the workpiece surface has rough texture based on the normal distribution information, as in step S004, the basic ray setting unit 18A in the illumination condition setting unit 18 makes the surface texture easier to see by having a camera observe directly reflected light. The basic ray setting unit 18A changes the radiation position of the light 42 and the angle of the basic ray 44 with respect to the workpiece surface (object surface) 53, the light distribution of the basic ray 44, and the radiance of the basic ray 44, so that the surface texture is easier to see. Furthermore, in step S009, which will be described later, the virtual camera setting unit 20 sets the virtual camera 40A so that reflected light 46 is incident.

[0040] 5 is an explanatory diagram showing an example of the position of the lighting 42 when the workpiece surface 53 has a rough texture. As shown in FIG. 5, basic light rays 44 emitted from the lighting 42 with a wide light distribution are reflected by the workpiece surface 53 and enter the virtual camera 40A as reflected light 46. In addition, a portion of the basic light rays 44 passes through the workpiece surface 53 to generate transmitted light 48. A virtual camera 40B may be set to capture the transmitted light 48.

[0041] In step S006, if the shape information analysis unit of the control unit 10 determines that the surface texture is smooth, for example, based on normal distribution information, the basic ray setting unit 18A in the illumination condition setting unit 18 of the control unit 10 sets the light distribution of the illumination to a second light distribution that is narrower than the first light distribution.

[0042] In step S007, if the shape information analysis unit of the control unit 10 determines that the properties of the work surface 53 are smooth based on the normal distribution information, as in step S006, the basic ray setting unit 18A in the lighting condition setting unit 18 of the control unit 10 changes the radiation position of the light 42, the angle of the basic ray 44 with respect to the work surface (object surface) 53, the light distribution of the basic ray 44, and the radiance of the basic ray 44 so that reflected light 46, which is a direct reflection of specular reflection when viewed from the viewpoint position, does not enter the virtual camera 40A.

[0043] 6 is an explanatory diagram showing an example of the position of the lighting 42 when the workpiece surface 53 has a smooth texture. As shown in FIG. 6, a basic light ray 44 emitted from the lighting 42 with a narrow light distribution is reflected by the workpiece surface 53, generating reflected light 46 and scattered light 50. In step S009, which will be described later, the virtual camera setting unit 20 sets the virtual camera 40A so that scattered light 50, not reflected light 46, is incident. In addition, a portion of the basic light ray 44 passes through the workpiece surface 53, generating transmitted light 48 and scattered light 52. A virtual camera 40B may be set to capture the scattered light 52.

[0044] In step S008, the material of the shape information is set in the material information setting unit 16 of the control unit 10. The material to be set is, for example, aluminum, iron, copper, stainless steel, chromium, titanium, synthetic resin, or the like.

[0045] In step S009, camera parameters such as the position, field of view, and sensor size of the virtual camera are set in the virtual camera setting unit 20 of the control unit 10. Also, in step S009, the virtual camera setting unit 20 sets the position of the virtual camera 40A or virtual camera 40B in the position described in step S005 or step S007, thereby setting the position of the virtual camera 40A or virtual camera 40B in accordance with the roughness of the workpiece surface 53, which is the surface of the object.

[0046] In step S010, the display image generation unit 22 of the control unit 10 performs rendering based on the information set by the shape data input unit 12, the virtual camera setting unit 20, the material information setting unit 16, the base ray setting unit 18A in the illumination condition setting unit 18, and the fill ray setting unit 18B in the illumination condition setting unit 18. The rendering tracks changes in optical properties due to reflection for the base ray, similar to the path tracing rendering method. Specifically, in step S010, the display image generation unit 22 generates an image that emphasizes the fine shape (irregularities) of the surface by acquiring a geometric shape (e.g., the average slope m of the minute faces on the object surface) including a normal distribution near a point of interest in screen space (e.g., the irradiation position of the base ray on the object surface).

[0047] In step S011, the image generated by the display image generating unit 22 of the control unit 10 is displayed on the display unit 24, and the process ends.

[0048] As described above, according to the first embodiment, the shape information analysis unit of the control unit 10 calculates the normal distribution function of a part or all of the area of ​​the object and sets the lighting conditions based on the calculation results. The shape information analysis unit 14 of the control unit 10 calculates the normal distribution of the shape data, thereby obtaining roughness information of the rendering surface. Therefore, lighting parameters with high visibility can be set according to the roughness of the display range. For example, if the object surface is smooth, the lighting distribution is set to a wide light distribution to brighten the reflected light from the object surface overall, and the lighting position is adjusted so that the viewpoint is not in the direction of specular reflection of the lighting. On the other hand, if the object surface is rough, the lighting distribution is set to a narrow light distribution, and the lighting position is set so that the viewpoint is in the direction of specular reflection of the lighting.

[0049] Next, a description will be given of embodiment 2. Embodiment 2 differs from embodiment 1 in that the illumination position is such that a light ray is emitted to the object from the same position as the coordinate position of the virtual camera, but other configurations are the same as embodiment 1. Therefore, the same components as embodiment 1 are denoted by the same reference numerals as embodiment 1, and detailed description thereof will be omitted.

[0050] 7 is an explanatory diagram showing an example of the position of the lighting 42 and the position of the virtual camera 40A in embodiment 2. As shown in Fig. 7, in embodiment 2, the base ray setting unit 18A of the lighting condition setting unit 18 sets the position of the lighting 42, which is a light source, so that the base ray 44 is emitted from the same position as the coordinates of the virtual camera 40A toward the workpiece surface 53, which is an object located on the optical axis of the virtual camera 40A.

[0051] Furthermore, every time the position of virtual camera 40A is changed, base ray setting unit 18A of illumination condition setting unit 18 changes the position of illumination 42 in conjunction with virtual camera 40A. Base ray setting unit 18A of illumination condition setting unit 18 sets the position of illumination 42, which is a light source, so that the position of the base ray moves in conjunction with the movement of the coordinate position of virtual camera 40A moving in virtual space, as indicated by arrow 54 in FIG.

[0052] As described above, according to the second embodiment, each time the position of the virtual camera 40A is changed, the position of the lighting 42 set by the basic ray setting unit 18A of the lighting condition setting unit 18 is also changed in conjunction with the position of the virtual camera 40A, and a display image is generated by the display image generation unit 22 and displayed on the display unit 24, thereby making it possible to clearly display changes in the roughness of the work surface 53.

[0053] Furthermore, as in embodiment 1, by changing the angle of the basic light ray 44 relative to the work surface 53, the light distribution of the basic light ray 44, and the radiance of the basic light ray 44 according to the roughness of the work surface 53, it is possible to generate an image that emphasizes the fine shape of the object's surface.

[0054] 10 Control unit, 12 Shape data input unit, 14 Shape information analysis unit, 16 Material information setting unit, 18 Lighting condition setting unit, 18A Basic light ray setting unit, 20 Virtual camera setting unit, 22 Display image generation unit, 24 Display unit, 31 CPU, 32 Main memory, 33 I / O interface, 34 Memory unit, 40A, 40B Virtual camera, 42 Lighting, 44 Basic light ray, 46 Reflected light, 48 Transmitted light, 50, 52 Scattered light, 100 Image processing device.

Claims

1. An image processing device comprising: a shape information analysis unit that calculates the geometric shape of the surface of an object including the normal distribution on the surface of the object, and calculates the roughness of the surface of the object based on the normal distribution; a basic ray setting unit that sets the emission position of a basic ray related to rendering of the object, the angle of the basic ray with respect to the surface of the object, the luminous intensity distribution of the basic ray, and the radiance of the basic ray, according to the roughness of the surface of the object calculated based on the normal distribution; a virtual camera setting unit that sets the position of a virtual camera observing the object according to the roughness of the surface of the object; and a display image generation unit that generates an image representing the surface shape of the object based on the geometric shape of the surface of the object including the normal distribution on the surface of the object.

2. The image processing device described in claim 1, wherein the shape information analysis unit determines that the surface of the object is rough if the value calculated by the normal distribution function related to the normal distribution is equal to or greater than a predetermined threshold, and determines that the surface of the object is smooth if the value calculated by the normal distribution function is less than the predetermined threshold, and the virtual camera setting unit sets the virtual camera so that, if the surface of the object is determined to be rough, the reflected light of the basic light beam on the surface of the object enters the virtual camera, and if the surface of the object is determined to be smooth, the scattered light of the basic light beam on the surface of the object enters the virtual camera.

3. An image processing device as described in claim 2, wherein the basic ray setting unit sets the light distribution of the basic ray to a first light distribution when the surface of the object is determined to be rough, and sets the light distribution of the basic ray to a second light distribution narrower than the first light distribution when the surface of the object is determined to be smooth.

4. An image processing device according to any one of claims 1 to 3, wherein the basic ray setting unit emits the basic ray from the same position as the coordinates of the virtual camera toward the object located on the optical axis of the virtual camera.

5. An image processing device according to claim 4, wherein the basic ray setting unit sets the light source of the basic ray so that it moves in conjunction with the coordinate position of the virtual camera which moves in virtual space.

6. An image processing method executed by a computer, comprising the steps of: calculating a geometric shape of the surface of the object including a normal distribution on the surface of the object; calculating a surface roughness of the object based on the normal distribution; setting an emission position of a basic ray for rendering the object, an angle of the basic ray with respect to the surface of the object, a luminous intensity distribution of the basic ray, and a radiance of the basic ray according to the surface roughness of the object calculated based on the normal distribution; setting a position of a virtual camera observing the object according to the surface roughness of the object; and generating an image representing the surface shape of the object based on the geometric shape of the surface of the object including the normal distribution on the surface of the object.

7. An image processing program that causes a computer to execute the steps of: calculating the geometric shape of the surface of the object, including the normal distribution on the surface of the object; calculating the surface roughness of the object based on the normal distribution; setting the emission position of a basic ray for rendering the object, the angle of the basic ray with respect to the surface of the object, the luminous intensity distribution of the basic ray, and the radiance of the basic ray, according to the surface roughness of the object calculated based on the normal distribution; setting the position of a virtual camera that observes the object, according to the surface roughness of the object; and generating an image that represents the surface shape of the object, based on the geometric shape of the surface of the object, including the normal distribution on the surface of the object.

Images