JP4932436B2 - Material information acquisition apparatus and material information acquisition method - Google Patents

Description

  The present invention relates to a texture information acquisition apparatus that measures physical characteristics that cause a texture on an object surface, and a method for acquiring texture information obtained from the physical characteristics.

  Conventionally, the color and pattern of the surface of an object are digitized by a camera, video, flatbed scanner, etc., and used to express the texture. The appearance of gloss and the like changes as the viewpoint and light source move. For the object surface that recognizes the degree of change as a texture, the texture is artificially reproduced by artificially adding an amount of information by an empirically obtained method. In order to add this amount of information related to the texture so that it does not become unnatural, skillful technology based on familiarity and experience of rendering theory is required.

  For example, Patent Document 1 proposes an apparatus that acquires shading information used when rendering.

JP 2004-152015 A

  In recent years, with the improvement of computer processing capabilities, computer graphics techniques have also improved dramatically. In order to construct a more realistic screen, it is essential to improve the texture expression.

  However, the conventional representation of the texture of the object surface is overwhelmingly lacking in the amount of information necessary to reproduce the physical phenomenon that originally occurs on the object surface. This is because it is difficult to measure physical characteristics related to texture information on a non-planar object surface, and compression technology and rendering technology for efficiently handling a huge amount of texture information have not been established. Is the cause.

  Texture information is caused as a comprehensive result of complex physical phenomena. For this reason, recognition that the technique for measuring texture information is required is increasing. Furthermore, a compression technique, a transfer technique, and a search technique for efficiently handling the enormous amount of texture information are also desired.

  Furthermore, the texture information will be specifically described. Currently, the expression of the texture of an object surface in computer graphics or the like is realized by a pseudo calculation method such as texture mapping. The texture information is used by manually processing object surface information acquired by a digital camera, digital video, flatbed scanner, or the like.

  Originally, the texture on the object surface is recognized as the “degree of change” when the incident light, the direction of viewing the object surface, or the like changes in color or gloss. This is caused by the physical fine structure of the surface, that is, microscopic unevenness, optical response characteristics such as reflection, refraction, transmission and interference.

  However, in the conventional object surface measurement such as a camera or a scanner, the light source direction and the detection direction are fixed, and thus the amount of information regarding the texture is overwhelmingly insufficient. In the production of computer graphics and the like, this lack of information is compensated by adding artificial and empirical information, and the texture is expressed in a pseudo manner.

  The camera and video can measure the surface of a three-dimensional object, but it is difficult to arbitrarily change the incident light and the viewing direction. Further, although a high resolution can be obtained with a flatbed scanner, only a sheet-like object can be applied, and the size is limited. Also, the incident light and the detection direction are fixed.

  As described above, it is difficult for the conventional technique to accurately acquire the texture information of the object.

  The present invention has been made in view of the above, and by combining measurement conditions, a detailed physical characteristic can be obtained, and a texture information acquisition apparatus and a texture information acquisition that can reproduce a realistic texture It aims to provide a method.

In order to solve the above-described problems and achieve the object, according to the present invention, a light irradiation step of irradiating illumination light including a plurality of wavelengths to a measurement position on an object;
An illumination condition control step for controlling the illumination condition for illuminating the illumination light;
A light detection step for detecting an optical response characteristic in an arbitrary direction from the measurement position;
A light detection condition control step for controlling a light detection condition for detecting an optical response characteristic;
An arithmetic control step for calculating texture information on the surface of the object using a change in the optical response characteristics related to the plurality of detected wavelengths based on the illumination conditions, the light detection conditions, and the detected optical response characteristics. Yes, and
The illumination condition is at least one of the irradiation direction of the illumination light, the wavelength region, and the deflection,
The detection condition is at least one of a detection direction of the optical response characteristic, a time change, and a wavelength shift.
A compression step of compressing the calculated texture information based on at least one of the illumination condition and the detection condition;
In the compression step,
The texture information on the surface of the object is at least one of a dependency smaller than a predetermined value with respect to a change in a specific measurement condition, a continuous change, and a change according to a specific physical law. When
It is possible to provide a texture information acquisition method characterized in that the information compression rate is set based on the change feature of the texture information.

  According to a preferred aspect of the present invention, the illumination condition control step is controlled to change the illumination condition, and / or the light detection condition control step is controlled to change the light detection condition. To do.

  Further, according to a preferred aspect of the present invention, it is desirable that the calculation control step calculates the texture information of the surface of the object based on the shape of the trajectory composed of changes in optical response characteristics related to a plurality of wavelengths or the speed at which the trajectory changes.

  According to a preferred aspect of the present invention, it is desirable that the calculation control step obtains a change in optical response characteristics regarding a plurality of wavelengths in the chromaticity diagram.

  Further, according to a preferred aspect of the present invention, the light detection condition includes a light receiving angle when detecting an optical response characteristic,
  It is desirable that the calculation control step further calculates the state of the surface of the object using the light receiving angle.

  Further, according to a preferred aspect of the present invention, in the light detection step, measurement is performed at a plurality of measurement positions so that at least a part of the measurement region overlaps,
  In the calculation control step, it is desirable to calculate and combine the relative relationship between a plurality of measurement positions in the overlappingly measured region, and calculate the texture information of the surface of the object having a larger area.

  According to a preferred aspect of the present invention, it is desirable to further include a measurement condition control step for setting a measurement condition including at least a measurement position of the object.

  According to a preferred aspect of the present invention, it is desirable that the measurement condition control step is synchronously controlled with the illumination condition control step and the light detection condition control step.

  According to a preferred aspect of the present invention, in the compression step,
  When the direction dependency of the texture information on the surface of the object is smaller than a predetermined value, a predetermined information compression rate can be set for the longitude direction of the illumination light irradiation direction and the longitude direction of the optical response characteristic detection direction. desirable.

  According to a preferred aspect of the present invention, in the compression step,
  When the texture information on the surface of the object changes continuously, it is desirable to set a predetermined information compression rate for the latitude direction of the illumination light irradiation direction and the latitude direction of the optical response characteristic detection direction.

  According to a preferred aspect of the present invention, in the compression step,
  When the time dependency of the texture information on the surface of the object is smaller than a predetermined value, it is desirable to set a predetermined information compression rate with respect to the temporal change of the texture information.

According to a preferred embodiment of the present invention,
A light irradiation step of irradiating illumination light including a plurality of wavelengths to a measurement position on the object;
An illumination condition control step for controlling the illumination condition for illuminating the illumination light;
A light detection step for detecting an optical response characteristic in an arbitrary direction from the measurement position;
A light detection condition control step for controlling a light detection condition for detecting an optical response characteristic;
An arithmetic control step for calculating texture information on the surface of the object using a change in the optical response characteristics related to the plurality of detected wavelengths based on the illumination conditions, the light detection conditions, and the detected optical response characteristics. Have
A template storing step for storing a plurality of templates related to the texture information of the surface of a typical object in advance;
A comparison step for comparing the calculated texture information with the texture information in the template;
As a result of the comparison step, it is desirable to predict the texture information of the surface of the object being measured, and to apply an optimum information compression method according to each template.

  Further, according to a preferred aspect of the present invention, a template storing step for storing a plurality of templates related to the texture information of the surface of a typical object in advance,
  A comparison step for comparing the calculated texture information with the texture information in the template;
  As a result of the comparison step, the texture information on the surface of the object being measured is predicted, and the texture information on the object surface is obtained with the measurement of the minimum necessary measurement position, without measuring all measurement positions in the measurement area. It is desirable to do.

Further, according to the present invention, a light source that irradiates illumination light including a plurality of wavelengths to a measurement position on an object;
A light source control unit for controlling the illumination conditions for illuminating the illumination light;
A photodetector for detecting an optical response characteristic in an arbitrary direction from the measurement position;
A photodetector control unit for controlling a light detection condition for detecting an optical response characteristic;
An arithmetic control unit that calculates the texture information of the surface of the object using the change in the optical response characteristics related to the plurality of detected wavelengths based on the illumination conditions, the light detection conditions, and the detected optical response characteristics. Yes, and
The arithmetic control unit calculates the texture information of the surface of the object by the shape of the trajectory consisting of changes in the optical response characteristics for a plurality of wavelengths or the speed at which the trajectory changes,
The illumination condition is at least one of the irradiation direction of the illumination light, the wavelength region, and the deflection,
The detection condition is at least one of a detection direction of the optical response characteristic, a time change, and a wavelength shift.
The arithmetic control unit compresses the calculated texture information based on at least one of the illumination condition and the detection condition,
In compression,
The texture information on the surface of the object is at least one of a dependency smaller than a predetermined value with respect to a change in a specific measurement condition, a continuous change, and a change according to a specific physical law. When
It is possible to provide a texture information acquisition apparatus characterized in that an information compression rate is set based on a feature of change in texture information.

Also, according to a preferred embodiment of the present invention further includes a measurement condition control unit,
The measurement condition control unit is desirably controlled synchronously with the light source control unit and the photodetector control unit.

  According to the present invention, it is possible to provide a texture information acquisition apparatus and a texture information acquisition method capable of obtaining detailed physical characteristics by combining measurement conditions and reproducing a realistic texture. Play.

  Embodiments of a texture information acquisition apparatus and a texture information acquisition method according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  FIG. 1 shows the principle of the texture information acquisition apparatus of the present invention. Thin parallel light that is very narrowly focused is irradiated as incident light Lin to a measurement point P that is one point of the object surface S of the object OB that is the measurement target.

  The light source incident angle α can be set in an arbitrary direction by the light source control unit 102. From the measurement point P, the optical response characteristics characterizing the texture due to various physical causes such as fine unevenness and reflection / refraction / transmission / interference / diffraction / absorption (hereinafter referred to as “light response” as appropriate). Lout is obtained. The photodetector 104 detects the optical response Lout.

  By setting the optical response detection angle β arbitrarily by the photodetector control unit 105, a detailed spatiotemporal structure of the optical response Lout can be obtained. At this time, the light source incident angle α and the light response detection angle β are not necessarily on the same plane.

  The measurement condition control unit 101 performs synchronous control with the light source control unit 102 and the photodetector control unit 105. Thereby, the position of the measurement point P, the measurement time, etc. are controlled.

  By setting the light source incident angle α and the light response detection angle β to specific conditions, the unevenness information of the measurement point P can be obtained. It is also possible to correct measurement conditions and optical responses from the obtained uneven conditions. The measurement condition control unit 101 adjusts necessary resolution, measurement accuracy, and measurement time according to the application, and performs planning (setting) of the measurement point P in the measurement region.

  Further, excitation light such as a laser can be used as the light source 103. At this time, if a biological tissue loaded with a fluorescent dye is a measurement target, it is also possible to measure the activity distribution of bovine body activity in the measurement region.

Here, the parameters controlled by the measurement condition control unit 101 include the following.
(1-1) Position of the measurement point P (Efficient measurement point scan setting in the measurement region)
(1-2) Measurement time (solution of trade-off with SN ratio)
(1-3) Switching between unevenness measurement and surface optical response characteristic measurement

Further, the light source control unit 102 changes the illumination condition for the light source 103 to illuminate the measurement point P of the object OB. Examples of lighting conditions are listed below.
(2-1) Irradiation direction, irradiation time (ON-OFF time)
(2-2) Irradiation intensity, wavelength, polarization state (2-3) NA (irradiation angle), irradiation pattern (spatial pattern, temporal pattern, etc.)
(2-4) Switching between laser light (excitation light) and diffused light

Further, the photodetector control unit 105 changes the light detection condition under which the photodetector 104 detects the optical response characteristic. Examples of light detection conditions are listed below.
(3-1) Detection method, detection time (ON-OFF time)
(3-2) Wavelength selection by wavelength filter, polarization selection by polarization filter (3-3) NA (detection angle), aperture diameter (detection intensity)
(3-4) Detection pattern (spatial pattern, temporal pattern, etc.)
(3-5) Fluorescence, phosphorescence (shift of energy such as wavelength and time)

Examples of measurement requests are listed below.
(4-1) Measurement resolution (size of measurement points)
(4-2) Measurement accuracy (temporal and spatial deviation of measurement points, tolerances such as color and light intensity)
(4-3) Measurement time (restrictions such as maintaining a specific state of the object to be measured)

  FIG. 2 shows a schematic configuration of the texture information acquisition apparatus 200 according to the second embodiment of the present invention. The light emitted from the light source 103 is converted into parallel light by the lens L1. The parallel light passes through the half mirror HM and is collected by the condenser lens L2. The lens L2 corresponds to the first lens.

  The object OB is placed on the stage 201. The stage 201 is a precision three-axis stage that can move minutely in three orthogonal directions. The stage 201 is driven and controlled by the stage control unit 202.

  By finely adjusting the position of the stage 201, the focal point of the condenser lens L2 and the measurement point P on the surface S of the object OB are matched. The present embodiment is an example of realizing a light source control unit that enables irradiation of incident light in an arbitrary direction to the measurement point P. The stage control unit 202 has a function of a light source control unit.

  Light from the measurement point P is reflected by the half mirror HM. The reflected light is collected by the lens L3. The lens L3 corresponds to the second condenser lens. The lens L3 has the same focal length as the condenser lens L2.

  A pinhole PH is installed at the focal position of the lens L3. The pinhole PH is provided at a predetermined position of the condenser lens L2, that is, a position substantially conjugate with the focal position. As a result, the photodetector 104 can obtain the maximum response when the spot diameter of light on the plane with the pinhole PH from the object OB becomes the smallest.

  When the spot diameter becomes the smallest by adjusting the stage 201 on which the object OB to be measured is placed in the vertical direction on the paper surface, the focal point of the condenser lens L2 and the surface S of the measurement object coincide. At this time, unevenness information can be obtained from the amount of movement of the stage 201 in the vertical direction.

  Next, the texture information acquisition apparatus 300 according to the second embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  Light from the light source 103 is converted into parallel light by the lens L1. The parallel light passes through the slit disk DSK1 and the Nipou disk DSK2.

  FIG. 4A shows the configuration of the slit disk DSK1. One slit SLT is formed in the disk-shaped slit disk DSK1.

  FIG. 4B shows the structure of the Niipou disc DSK2. A plurality of openings HL are spirally arranged in the disc-shaped Nipkow disc DSK2.

  Returning to FIG. 3, the description will be continued. The slit disk DSK1 and the tip disk DSK2 are arranged so as to be coaxial with the optical axis of the condenser lens L2. The slit disk DSK1 and the tip disk DSK2 are each configured to be rotatable about the optical axis. The position through which the parallel light passes can be arbitrarily determined by the combination of the two discs, the slit disc DSK1 and the tip disc DSK2.

  The slit disk DSK1 and the Nipkow disk DSK2 correspond to a light source control unit, in particular, a deflection unit that changes the position of light incident on the condenser lens L2. The polarization unit changes the above-described illumination condition in which the illumination light transmitted through the condenser lens L2 illuminates the measurement point P of the object OB.

  The parallel light is condensed at the focal position of the condenser lens L2 by the condenser lens L2, regardless of which position of the slit disk DSK1 and the tip disk DSK2. The focal position of the condenser lens L2 and the measurement point P on the surface S of the object OB to be measured are made to coincide with each other by the same stage drive as in the first embodiment.

  Accordingly, the light source incident angle α (see FIG. 1) can be controlled by the position through which the parallel light determined by the combination of the two disks, the slit disk DSK1 and the Nipkow disk DSK2, passes. When incident light is irradiated, an optical response Lout (reflection, refraction, transmission, interference, diffraction, etc.) is generated from the measurement point P due to its physical characteristics.

  The light response Lout is again converted into parallel light by passing through the condenser lens L2. The light converted into parallel light is reflected by the half mirror HM.

  The reflected light is incident on the CCD 301. The CCD 301 can detect the light response distribution two-dimensionally. The light distribution obtained by the CCD 301 indicates the direction characteristic of the light response at the measurement point P.

  The measurement point P can be arbitrarily set in the entire measurement region by moving the stage 201 (precision three-axis stage) in two horizontal (x-axis, y-axis) directions perpendicular to the horizontal direction. Then, the same measurement is repeated over the entire measurement region. Thereby, the light response characteristic space of the entire surface S of the object OB, that is, texture information can be obtained.

  Next, a texture information acquisition apparatus 500 according to Embodiment 3 of the present invention will be described. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. In this embodiment, a micro-rotation light source array and a micro-rotation photodiode array are used. FIG. 5 shows a schematic configuration of the texture information acquisition apparatus 500.

  The texture acquisition information apparatus 500 according to the present embodiment includes a main body 503 and a head unit 515. The main body unit 503 includes a measurement condition control unit 101 and an arithmetic control unit 505. The head unit 515 includes at least a minute rotation light source array, which will be described later, a light source control unit 102, a minute rotation photodiode array, which will be described later, and a photodetector control unit 105, and is configured integrally.

  The head unit 515 is configured to be portable. A measurer (not shown) can acquire the texture information of the surface S by the procedure described later by bringing the head unit 515 close to and in contact with the object OB. In addition, the head unit 515 and the main body 503 are configured to be communicable by wire or wireless.

  The arithmetic control unit 505 calculates the texture information of the surface S of the object OB based on the illumination condition, the light detection condition, the measurement condition, and the detected optical response characteristic as described above.

  FIG. 6 shows a cross-sectional configuration of the head unit 515. The head unit 515 includes a plurality of light emitting elements 501a, 501b,... 501e and a plurality of photodiode elements 502a, 502b,.

  Each light emitting element is configured by incorporating a light source such as a light emitter or a mirror into a minute structure that is supported by thin beams (hinges) supported at both ends and can be rotated (tilted) in a predetermined direction. Each photodiode element is configured by incorporating a photodetector such as a photodiode into a minute structure that is supported by a thin beam (hinge) that is supported at both ends and that can rotate (tilt) in a predetermined direction. .

  The light emitting element 501a and the like and the photodiode element 502a and the like can be easily manufactured by the MEMS technology.

  Hereinafter, for convenience of description, the light emitting elements 501a and the like are appropriately referred to as a “micro-rotation light source array”, and the photodiode elements 502a and the like are appropriately referred to as a “micro-rotation photodiode array”.

  FIG. 7A shows a cross-sectional configuration of the light-emitting element 501a. The light emitting element 501 a includes a light emitting unit 510 and a lens 520. Further, as shown in FIG. 7B, the photodiode element 502a includes three photodiodes 530 and color filters FB, FG, FR arranged corresponding to the photodiodes 530. Yes. The color filter FB transmits blue light. The color filter FR transmits red light. The color filter FG transmits green light. In this way, it is possible to divide the photodiode into a plurality of parts and to extract only necessary information (wavelength and polarization) from the optical response detected by the wavelength filter or the polarization filter.

  Here, the micro-rotation light source array has functions of a light source and a light source control unit. That is, the micro-rotation light source array can change the illumination conditions, such as the direction and the irradiation time, of each of the plurality of light emitting elements 501a arranged in an array.

  The micro-rotating photodiode array has functions of a photodetector and a photodetector control unit. That is, the photodetector control unit can change the light detection conditions, such as the direction and the detection time, of each of the plurality of photodiode elements 502a arranged in an array.

  As shown in FIG. 8, the light emitting elements 501a and the like and the photodiode elements 502a and the like are alternately arranged two-dimensionally. Adjacent elements are configured to rotate in the vertical direction.

  Both the light emitting element 501a and the photodiode element 502a and the like are supported by the hinge as described above. Each element is formed with a drive coil 801. For example, each element can be rotated (tilted) by electrostatic attraction.

  With this configuration, the surface S of the object OB can be scanned in two directions by rotating in the direction perpendicular to the adjacent structure.

  In this embodiment, a procedure for acquiring a texture will be described. First, as shown in FIG. 9, light is irradiated from a single light emitting element 501c with the direction fixed to the measurement point P. In this state, the micro-rotation photodiode array is scanned once in the rotation direction. At this time, the direction in which the maximum detection intensity is obtained in each of the photodiode elements 502a, 502b,. Then, the arithmetic control unit 505 calculates the unevenness information of the measurement point P based on the arrangement position in the minute rotation photodiode array and the maximum detection direction.

  Next, as shown in FIG. 10, light is irradiated while switching the light emitting elements 501a, 501b,... 501e with respect to the measurement point P in consideration of the calculated unevenness information. Thereby, incident light can be irradiated to the measurement point P at various angles.

  The photodiode array is scanned once in response to light irradiation from each of the light emitting elements 501a, 501b,... 501e, and the directional characteristics of the optical response are obtained. Measurement according to this procedure is repeated for the entire measurement region. Thereby, the unevenness information of the entire surface S of the object OB and the light response characteristics (texture information) can be obtained.

  Next, a procedure for efficiently compressing the obtained optical response characteristic when the arithmetic control unit 505 calculates the texture information will be described. If the measurement point P on the surface S of the object OB is irradiated with incident light from all directions and the optical response is detected from all directions, the amount of information becomes enormous.

  Here, for example, when the surface S of the object OB to be measured is a uniform surface, the optical response does not change much with respect to the change in the longitude direction of the incident light as shown in FIG. Using this fact, it becomes possible to set a high compression rate in the longitude direction.

  In addition, as shown in FIG. 12, the optical response changes continuously and rarely changes discontinuously with respect to the change of the incident light in the latitudinal direction. Thus, when it is found that the optical response changes continuously, an information compression method suitable for this can be used.

  In addition to this, the optical response is likely to change continuously at adjacent measurement points P, and the continuity of the temporal change of the optical response can be expected for an object surface having temporal changes such as phosphorescence. Can be used for information compression.

  As described above, it is desirable to use an information compression method suitable for a factor with little change or a continuously changing factor in consideration of physical factors on the object surface. Thereby, the information regarding an optical response can be compressed with high efficiency. As a result, it becomes possible to make the information model remarkably compact and easy to handle.

  Also, a typical template of optical response characteristics (texture information) on the surface S of the object OB can be used. In this case, by sequentially comparing the acquired optical response characteristics with the template, the material of the surface S of the object OB to be measured, unevenness information, and the like can be estimated.

  When using a template, measurement is first made with a coarse resolution. Next, necessary measurement points are reset according to the estimation result based on the comparison with the template. Thereby, it can measure efficiently.

  In addition, regarding the selection of parameters related to compression such as directional characteristics, resolution, quantization, and encoding, if the measurement results are sufficient to determine that the estimation is appropriate, the most efficient compression parameter set is measured according to the template. Can be applied to the results.

  As described above, the direction dependency of the optical response characteristic (texture information) and high-efficiency compression of information using the same can be performed.

Moreover, in the texture information compression method using a template, it is desirable to have the following steps.
A template storing step for storing a plurality of templates related to the texture information of the surface of a typical object in advance, a comparison step for comparing the calculated texture information with the texture information in the template, and a result of the comparison step, This is a step of predicting the texture information of the surface of the object and applying an optimal information compression method according to each template. Thereby, the texture information can be efficiently compressed.

More preferably, it is desirable to have the following steps.
A template storing step for storing a plurality of templates related to the texture information of the surface of a typical object in advance, a comparison step for comparing the calculated texture information with the texture information in the template, and a result of the comparison step, In this step, the texture information on the surface of the object is predicted, and the texture information on the surface of the object is acquired by measuring the minimum necessary measurement position without measuring all the measurement positions in the measurement region. As a result, the texture information can be more efficiently compressed.

Here, another example of the texture information processing will be further described.
As shown in (a) of FIG. 13, the measurement is performed by changing the light receiving angle φ in various ways with respect to the red colored paper having a rough surface (an uneven state or a textured state). FIG. 13B shows the measurement result at this time.

  FIG. 14 shows the measured spectrum information on the xy chromaticity diagram. On the xy chromaticity diagram, the measured spectral information is a linear or curved locus L. And the shape of the locus | trajectory L and the speed which draws a locus | trajectory can be used as texture information.

  For example, when a smooth red color surface is measured, as shown in FIG. 15, the locus L reaches the middle region (corresponding to white color) of the xy chromaticity diagram, and a highlight is generated. What is highlighted is a slight angle region before and after the light receiving angle (measurement condition) E in FIG. When the light receiving angle is further scanned, the locus L moves so as to suddenly go to the white region and immediately return to the red region in the xy chromaticity diagram.

  Further, when a rough red surface is measured, as shown in FIG. 16, the locus L moves (changes) in the red region without highlighting in the xy chromaticity diagram. In both cases of FIGS. 15 and 16, the locus L is linear in the xy chromaticity diagram. The difference between the smoothness of the surface and the roughness can be evaluated by the movement of the points on the linear locus L.

For example, when the trajectory L is a straight line, the movement state of the point is set with the light receiving angle φ as a parameter, and the measured spectrum value when φ = 0 ° is (x, y) = (x x0, y0), it can be expressed as follows. However, γ is a constant and is an angle formed by the x axis of the xy chromaticity diagram and the locus L.
x = cosγ · f (φ) + x0
y = sinγ · f (φ) + y0

  Then, a point (x, y) = (cosγ · f (φ0) + x0, sinγ · f (φ0) + y0) or γ on a locus L using a certain light receiving angle φ0 is set to a value representing “color”. Can do. Further, f (φ) can be a function indicating the “smoothness” of the surface. In this way, the texture information of the pigment can be obtained by “color” and “smoothness”.

  Next, a case where the locus L cannot be regarded as a straight line on the xy chromaticity diagram (when the texture information cannot be compressed) will be described. This is the case of a surface that is not colored using a dye, for example, a surface that causes thin film interference. The surface measurement conditions are shown in FIG. Unlike the measurement conditions of FIG. 13, the illumination angle is also changed simultaneously with the light reception angle.

In this case, as shown in FIG. 18, in the xy chromaticity diagram, the locus L has a continuous curved shape. Therefore, assuming that the light reception angle φ is a parameter and the measured spectrum value when φ = 0 ° is (x, y) = (x0, y0) on the xy chromaticity diagram, Can be represented.
x = f (φ) + x0
y = g (φ) + y0

  For this reason, by fitting the locus L with, for example, a quadratic polynomial of the parametric variable φ, the representative amount of the texture information can be extracted and / or compressed. The above-mentioned texture information processing is mainly given as an example when measuring only by changing the light receiving angle φ, but also when measuring by changing only the illumination angle or when measuring by changing both the illumination angle and the light receiving angle. The texture information can be processed in the same way.

  Thus, instead of compressing the data acquired (measured) for each light reception angle and illumination angle, the data moves for each light reception angle and illumination angle on the xy chromaticity diagram using the xy chromaticity diagram as a template. By recording the trajectory, the “texture information” can be evaluated.

  As described above, in the present invention, a point on the surface of an object to be measured is irradiated with incident light from an arbitrary direction, and an optical response from the measurement point is detected from an arbitrary direction. Thereby, the physical fine structure of the measurement point is measured. Then, by performing this in the entire measurement region, it is possible to obtain texture information on the object surface.

  More preferably, since the measurement surface is not necessarily a flat surface, it is desirable to measure unevenness information on the surface in advance and correct the measurement conditions and optical response based on the unevenness information. Further, by combining measurement conditions, more detailed physical characteristics can be obtained. As a result, a more realistic texture can be reproduced.

  In addition, in order to obtain the texture information, a very large amount of measurement is required using several measurement conditions as parameters, and the amount of information is enormous. However, in the present invention, as described above, it is possible to apply a very high compression to a specific parameter by considering the physical properties of the object surface with respect to the measurement conditions. Thereby, a compact and easy-to-handle texture information model is constructed.

  As described above, in the present invention, the physical fine structure itself on the object surface is measured in detail to obtain the texture information. Further, at one point on the object surface, the incident light direction and the detection direction are scanned independently in all directions, and the physical characteristics at the measurement point are measured. In addition, various physical characteristics can be measured by combining measurement conditions such as wavelength shift, polarization shift, and spatiotemporal change in the detection direction, such as the wavelength, polarization, and spatiotemporal pattern of incident light.

  It is a feature of the present invention that the texture information is obtained by performing this measurement at all points on the measurement area of the object surface. By combining the measurement conditions, the unevenness of the object surface can be measured, so that it is possible to measure while correcting the influence of the unevenness. Moreover, it can apply also to a wider measurement area | region by measuring repeatedly several times.

  Moreover, since the acquired texture information measures the physical fine structure at the measurement point in detail, the amount of information becomes enormous. However, the texture information may not change much with respect to a specific measurement condition due to the measurement condition and the physical characteristics of the surface. By using this measurement condition as a parameter, the texture information can be compressed with high efficiency.

  Even when the texture information changes with respect to the measurement conditions, a high compression method can be applied by considering the physical meaning.

  By acquiring and compressing the texture information on the surface of these objects, it is possible to more easily acquire the texture expression that has been realized by artificial and empirical information loads so far and use high-quality ones. become.

  Further, according to a preferred aspect of the present invention, in the light detection step, measurement is performed at a plurality of measurement positions so that at least a part of the measurement region overlaps, and in the calculation control step It is desirable to calculate and combine the relative relationships of the plurality of measurement positions to calculate texture information on the surface of the object having a larger area. Thereby, texture information can be obtained efficiently.

  Further, according to a preferred aspect of the present invention, in the compression step, when the time dependency of the texture information on the surface of the object is smaller than a predetermined value, a predetermined information compression rate is set for the temporal change of the texture information. It is desirable to do. Thereby, texture information can be more efficiently compressed.

  The present invention can be said to be an innovative technique in the expression of texture that has been reproduced by empirical and skillful techniques in computer graphics related techniques. Until now, in computer graphics-related technologies, simpler and higher-quality expression techniques have been established by digitizing real-world ones (for example, three-dimensional shapes and movements). Three-dimensional shape scanners and motion capture are typical examples, and are already accepted as general techniques. The present invention is a technique for digitizing real-world ones in terms of texture expression, and can be said to have a high possibility of being accepted worldwide as a general technique. The present invention can take various modifications without departing from the spirit of the present invention.

  As described above, the present invention is useful for an apparatus that obtains texture information of an object.

It is a figure explaining the principle of this invention. It is a figure which shows schematic structure of the texture information acquisition apparatus of Example 1 of this invention. It is a figure which shows schematic structure of the texture information acquisition apparatus of Example 2 of this invention. It is a figure which shows the structure of a disk. It is a figure which shows schematic structure of the texture information acquisition apparatus of Example 3 of this invention. FIG. 6 is a diagram illustrating a schematic configuration of a head unit according to a third embodiment. FIG. 10 is another diagram illustrating a schematic configuration of the head unit according to the third embodiment. FIG. 10 is still another diagram illustrating a schematic configuration of the head unit according to the third embodiment. FIG. 10 is another diagram illustrating a schematic configuration of a head unit according to Embodiment 3. FIG. 10 is still another diagram illustrating a schematic configuration of the head unit according to the third embodiment. It is a figure which shows the property of texture information. It is another figure which shows the property of texture information. It is a figure which shows the measurement conditions and measurement result of surface reflection. It is a figure which shows the locus | trajectory in xy chromaticity diagram. It is another figure which shows the locus | trajectory in xy chromaticity diagram. It is another figure which shows the locus | trajectory in xy chromaticity diagram. It is another figure which shows the measurement conditions and measurement result of surface reflection. It is another figure which shows the locus | trajectory in xy chromaticity diagram.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Measurement condition control part 102 Light source control part 103 Light source 104 Photodetector 105 Photodetector control part 200 Texture information acquisition apparatus 201 Stage 202 Stage control part 300 Texture information acquisition apparatus 301 CCD
500 Texture information acquisition device 501a to 501e Light source element 502a to 502e Photodiode element 503 Main unit 505 Calculation control unit 510 Light emitting unit 520 Lens 530 Photodiode 515 Head unit 801 Driving coil FR, FG, FB Color filter L1 lens L2 lens L3 lens DSK1 Slit disk DSK2 Nipou disk HM Half mirror P Measurement point OB Object S Surface α Light source incident angle β Photoresponse detection angle

Claims (15)

A light irradiation step of irradiating illumination light including a plurality of wavelengths to a measurement position on the object;
An illumination condition control step for controlling an illumination condition for illuminating the illumination light;
A light detection step of detecting an optical response characteristic in an arbitrary direction from the measurement position;
A light detection condition control step for controlling a light detection condition for detecting the optical response characteristic;
Based on the illumination conditions, the light detection conditions, and the detected optical response characteristics, the texture information of the surface of the object is calculated using changes in the optical response characteristics related to the detected plurality of wavelengths. possess an arithmetic control step,
The illumination condition is at least one of an irradiation direction of the illumination light, a wavelength region, and deflection,
The detection condition is at least one of a detection direction of the optical response characteristic, a time change, and a wavelength shift.
A compression step of compressing the calculated texture information based on at least one of the illumination condition and the detection condition;
In the compression step,
The texture information on the surface of the object is at least one of a dependency smaller than a predetermined value with respect to a change in a specific measurement condition, a continuous change, and a change according to a specific physical law. At one time
A texture information acquisition method, wherein an information compression rate is set based on a change feature of the texture information.   The said illumination condition control step is controlled to change the illumination condition, and / or the light detection condition control step is controlled to change the light detection condition. Material information acquisition method.   3. The calculation control step calculates the texture information of the surface of the object based on a shape of a trajectory formed by a change in optical response characteristics related to the plurality of wavelengths or a speed at which the trajectory changes. The material information acquisition method described in 1.   The texture information acquisition method according to any one of claims 1 to 3, wherein the calculation control step obtains a change in optical response characteristics related to the plurality of wavelengths in a chromaticity diagram. The light detection condition includes a light receiving angle when detecting the optical response characteristic,
5. The texture information acquisition method according to claim 1, wherein the calculation control step further calculates a state of the surface of the object using the light receiving angle. In the light detection step, measurement is performed at the plurality of measurement positions so that at least a part of the measurement region overlaps,
The calculation control step includes calculating and synthesizing a relative relationship between a plurality of the measurement positions in an overlapping measurement area, and calculating the texture information of the surface of the object having a larger area. The texture information acquisition method according to any one of 1 to 5. The texture information acquisition method according to any one of claims 1 to 6, further comprising a measurement condition control step of setting a measurement condition including at least a measurement position of the object. The texture information acquisition method according to claim 7, wherein the measurement condition control step performs synchronous control with the illumination condition control step and the light detection condition control step. In the compression step,
When the direction dependency of the texture information on the surface of the object is smaller than a predetermined value, a predetermined information compression rate is set for the longitude direction of the illumination light irradiation direction and the longitude direction of the optical response characteristic detection direction. The texture information acquisition method according to claim 1, wherein the texture information acquisition method is set. In the compression step,
When the texture information on the surface of the object continuously changes, a predetermined information compression rate is set for the latitude direction of the illumination light irradiation direction and the latitude direction of the optical response characteristic detection direction. The texture information acquisition method according to claim 1, wherein: In the compression step,
The texture information acquisition method according to claim 1, wherein when a time dependency of the texture information on the surface of the object is smaller than a predetermined value, a predetermined information compression rate is set with respect to a temporal change of the texture information. . A light irradiation step of irradiating illumination light including a plurality of wavelengths to a measurement position on the object;
An illumination condition control step for controlling an illumination condition for illuminating the illumination light;
A light detection step of detecting an optical response characteristic in an arbitrary direction from the measurement position;
A light detection condition control step for controlling a light detection condition for detecting the optical response characteristic;
Based on the illumination conditions, the light detection conditions, and the detected optical response characteristics, the texture information of the surface of the object is calculated using changes in the optical response characteristics related to the detected plurality of wavelengths. An arithmetic control step,
A template storing step for storing a plurality of templates related to the texture information of the surface of the typical object in advance;
A comparison step of comparing the calculated texture information with the texture information in the template;
A texture information acquisition method characterized by predicting the texture information of the surface of the object being measured as a result of the comparison step and applying an optimum information compression method according to each template. A template storing step for storing a plurality of templates related to the texture information of the surface of the typical object in advance;
A comparison step of comparing the calculated texture information with the texture information in the template;
As a result of the comparison step, the texture information of the surface of the object being measured is predicted, and the measurement of the minimum measurement position is performed without performing measurement of all measurement positions in the measurement region. The texture information acquisition method according to any one of claims 1 to 11, wherein the texture information is acquired. A light source that emits illumination light including a plurality of wavelengths to a measurement position on an object;
A light source control unit for controlling an illumination condition for illuminating the illumination light;
A photodetector for detecting an optical response characteristic in an arbitrary direction from the measurement position;
A photodetector control unit for controlling a light detection condition for detecting the optical response characteristic;
Based on the illumination conditions, the light detection conditions, and the detected optical response characteristics, the texture information of the surface of the object is calculated using changes in the optical response characteristics related to the detected plurality of wavelengths. An arithmetic control unit,
The calculation control unit calculates the texture information of the surface of the object according to a shape of a trajectory composed of changes in optical response characteristics regarding the plurality of wavelengths or a speed at which the trajectory changes,
The illumination condition is at least one of an irradiation direction of the illumination light, a wavelength region, and deflection,
The detection condition is at least one of a detection direction of the optical response characteristic, a time change, and a wavelength shift.
The arithmetic control unit compresses the calculated texture information based on at least one of the illumination condition and the detection condition,
In the compression,
  The texture information on the surface of the object is at least one of a dependency smaller than a predetermined value with respect to a change in a specific measurement condition, a continuous change, and a change according to a specific physical law. At one time
  A texture information acquisition apparatus characterized in that an information compression rate is set based on a change feature of the texture information. Furthermore, it has a measurement condition control unit,
The texture information acquisition apparatus according to claim 14, wherein the measurement condition control unit performs synchronous control with the light source control unit and the photodetector control unit.

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