BRDF reflection space distribution calibration value measurement method, system, device, medium and program product

Abstract

The invention relates to the technical field of detection and calibration, and provides a BRDF reflection space distribution calibration value measurement method, system and device, a medium and a program product, and the method comprises the steps: respectively obtaining the signal current ratios of a to-be-measured sample and a standard diffuse reflection plate under various characteristic conditions; determining a relative calibration value of the to-be-measured sample under each characteristic condition based on the signal current ratio and the calibrated magnitude of the standard diffuse reflection plate on the absolute calibration device under each characteristic condition; based on any calibration value under any characteristic condition in the relative calibration values, performing normalization processing on each relative calibration value to obtain a normalized measurement value; determining an absolute calibration value of the to-be-tested sample under any characteristic condition based on the magnitude of the standard diffuse reflection plate under any characteristic condition; and determining the BRDF calibration value of the to-be-measured sample based on the normalized measurement value of the to-be-measured sample and the absolute calibration value under any characteristic condition. According to the invention, accurate and reliable measurement of the BRDF value of the measurement sample can be simply and accurately realized.

Description

Technical Field

[0001] The present invention relates to the field of detection and calibration technology, and in particular to a method, system, device, medium and program product for measuring a BRDF reflection space distribution calibration value. Background Art

[0002] The bidirectional reflectance distribution function (BRDF) of a material represents the reflection characteristics of the object surface at any observation angle under different incident angles. It describes the distribution of reflected light in all directions of space when the incident light in a specified direction is reflected by the material surface. It is the best physical quantity to effectively describe the light radiation characteristics of the target surface in hemispherical space.

[0003] In the related art, the calibration of the BRDF measurement device is usually only performed for a certain characteristic condition, resulting in inaccurate measurements under other characteristic conditions. Summary of the invention

[0004] The present invention provides a method, system, device, medium and program product for measuring a BRDF reflection space distribution calibration value, which are used to solve the defect of inaccurate BRDF value measurement in the prior art.

[0005] The present invention provides a method for measuring a BRDF reflection space distribution calibration value, comprising: Respectively obtain the signal current ratio of the sample to be tested and the standard diffuse reflection plate under various characteristic conditions; Based on the signal current ratio and the value of the standard diffuse reflection plate under each characteristic condition calibrated on the absolute calibration device, determine the relative calibration value of the sample to be tested under each characteristic condition; Based on any calibration value under any characteristic condition in the relative calibration values, normalizing each of the relative calibration values ​​to obtain a normalized measurement value of the sample to be tested; Determine the absolute calibration value of the sample to be tested under any of the characteristic conditions based on the value of the standard diffuse reflection plate under any of the characteristic conditions; Based on the normalized measurement value of the sample to be tested and the absolute calibration value under any characteristic condition, the BRDF calibration value of the sample to be tested is determined.

[0006] According to the method for measuring the BRDF reflection spatial distribution calibration value provided by the present invention, the signal current ratio of the sample to be tested and the standard diffuse reflection plate under the characteristic conditions is respectively obtained, including: Respectively obtaining the measurement signal current value and the monitoring signal current value of the sample to be tested and the standard diffuse reflection plate under the above-mentioned characteristic conditions; The ratio between the measured signal current value and the monitored signal current value is taken as the signal current ratio.

[0007] According to the method for measuring the BRDF reflection spatial distribution calibration value provided by the present invention, the absolute calibration value of the sample to be measured under any characteristic condition is determined based on the value of the standard diffuse reflection plate under any characteristic condition, including: Performing absolute value calibration on the signal current ratio of the sample to be tested and the standard diffuse reflection plate respectively to obtain an absolute signal current ratio; Based on the absolute signal current ratio and the value of the standard diffuse reflection plate under any of the characteristic conditions, the absolute calibration value of the sample to be tested under any of the characteristic conditions is determined.

[0008] According to the measurement method of the BRDF reflection spatial distribution calibration value provided by the present invention, the characteristic conditions include: the incident light and the reflected light are in the same plane, and the coordinate position of the incident light irradiated on the sample to be measured is the same as the coordinate position of the reflected light emitted from the sample to be measured.

[0009] The present invention also provides a measurement system for a BRDF reflection space distribution calibration value, comprising: Absolute calibration device, used to calibrate the value of the standard diffuse reflector under various characteristic conditions; A BRDF measuring device is used to obtain the signal current ratio of the sample to be tested and the standard diffuse reflection plate under various characteristic conditions; A processor is used to determine the relative calibration value of the sample to be tested under each characteristic condition based on the value of the standard diffuse reflection plate under each characteristic condition calibrated on the absolute calibration device; normalize the relative calibration value based on the value of any one of the characteristic conditions to obtain the normalized measurement value of the sample to be tested; determine the absolute calibration value of the sample to be tested under any one of the characteristic conditions based on the value of the standard diffuse reflection plate under any one of the characteristic conditions; determine the BRDF calibration value of the sample to be tested based on the normalized measurement value of the sample to be tested and the absolute calibration value under any one of the characteristic conditions.

[0010] According to the measurement system of the BRDF reflection space distribution calibration value provided by the present invention, the wavelength range of the measurement light source of the absolute calibration device covers the ultraviolet, visible and infrared bands.

[0011] According to the measurement system of the BRDF reflection space distribution calibration value provided by the present invention, the detector of the absolute calibration device meets the detection requirements of the ultraviolet, visible and infrared bands.

[0012] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, a method for measuring a BRDF reflection spatial distribution calibration value as described above is implemented.

[0013] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements a method for measuring a BRDF reflection spatial distribution calibration value as described in any one of the above.

[0014] The present invention also provides a computer program product, comprising a computer program, which, when executed by a processor, implements a method for measuring a BRDF reflection spatial distribution calibration value as described above.

[0015] The BRDF reflection space distribution calibration value measurement method, system, device, medium and program product provided by the present invention calculate the normalized measurement value of the sample to be measured and the absolute calibration value under any characteristic condition through the value of each characteristic condition of the standard diffuse reflection plate calibrated on the absolute calibration device, and then obtain the BRDF calibration value of the sample to be measured through a certain algorithm. The system does not require the BRDF measurement device to have a strict absolute measurement function, and only relies on a standard diffuse reflection white plate with a one-to-one corresponding calibration value in its sample measurement space, so as to simply and accurately achieve accurate and reliable measurement of the BRDF value of the measured sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a flow chart of the method for measuring the BRDF reflection space distribution calibration value provided by the present invention.

[0018] Figure 2 It is a structural schematic diagram of a measurement system for BRDF reflection space distribution calibration value provided by the present invention.

[0019] Figure 3 It is a structural schematic diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Figure 1 is a flow chart of the method for measuring the BRDF reflection space distribution calibration value provided by the present invention, such as Figure 1 As shown, the method comprises the following steps: Step 110, respectively obtaining the signal current ratio of the sample to be tested and the standard diffuse reflection plate under various characteristic conditions.

[0022] Specifically, the sample to be tested is a sample for which the BRDF reflection spatial distribution calibration value needs to be measured.

[0023] When the measurement conditions meet the requirements of large field of view and small spot, the expression of bidirectional reflectance distribution function (BRDF) can be expressed as:

[0024] in, θ i is the incident angle, is the incident azimuth, is the coordinate position of the incident light on the sample, λ is the wavelength, θ r is the reflection angle, is the reflection azimuth, is the coordinate position of the reflected light emitted from the sample, dA r is the emission position on the sample A surface element at .

[0025] Here, each characteristic condition includes that the incident light and the reflected light are in the same plane, and the coordinate position of the incident light irradiating the sample to be measured is the same as the coordinate position of the reflected light emitting from the sample to be measured.

[0026] That is, the characteristic wavelength can be set to λ 0 , the coordinate position of the incident light on the sample is , the coordinate position of the reflected light emitted from the sample is also , the incident light and the reflected light are in the same plane, then, λ -> λ0 ; ; ; Then, the expression of the bidirectional reflectance distribution function can be simplified to .

[0027] In this step, a signal current ratio of the sample to be tested and the standard diffuse reflector under various characteristic conditions can be obtained by a BRDF measuring device. In some embodiments, step 110 specifically includes: Step 111, respectively obtaining the measurement signal current value and the monitoring signal current value of the sample to be tested and the standard diffuse reflection plate under the above-mentioned characteristic conditions; Step 112: taking the ratio between the measured signal current value and the monitored signal current value as the signal current ratio.

[0028] Here, the signal current ratio of the sample to be tested is the ratio between the measured signal current value of the sample to be tested and the monitored signal current value, and the signal current ratio of the standard diffuse reflector is the ratio between the measured signal current value of the standard diffuse reflector and the monitored signal current value. It can be expressed as:

[0029] in, C sample is the signal current ratio of the sample to be tested, i sample is the measurement signal current value of the sample to be tested, i s-monitor is the monitoring signal current value of the sample to be tested. C ref is the signal current ratio of the standard diffuse reflector, i ref is the measured signal current value of the standard diffuse reflection plate, i r-monitor is the monitoring signal current value of the standard diffuse reflection plate.

[0030] Step 120, based on the signal current ratio and the value of the standard diffuse reflection plate under each characteristic condition after calibration on the absolute calibration device, determine the relative calibration value of the sample to be tested under each characteristic condition.

[0031] Specifically, the values ​​of the standard diffuse reflection plate under various characteristic conditions calibrated on the absolute calibration device are pre-calibrated, and the values ​​include the values ​​under various characteristic conditions, such as the values ​​under incident angles of 0 to 75 degrees, reflection angles of 0 to 75 degrees, incident azimuths of 0 degrees, and reflection azimuths of 0 to 360 degrees.

[0032] On this basis, the relative calibration value of the sample to be tested under each characteristic condition can be determined based on the ratio between the signal current ratio of the sample to be tested and the signal current ratio of the standard diffuse reflector, as well as the value of the standard diffuse reflector under each characteristic condition calibrated on the absolute calibration device. The relative calibration value here can be expressed as:

[0033] In the formula, is the relative calibration value of the sample to be tested under each characteristic condition, The standard diffuse reflector is calibrated on an absolute calibration device. The value under characteristic conditions, C sample is the signal current ratio of the sample to be tested, C ref is the signal current ratio of the standard diffuse reflection plate.

[0034] Step 130: Based on any calibration value under any characteristic condition in the relative calibration value, normalize each relative calibration value to obtain a normalized measurement value of the sample to be tested.

[0035] After obtaining the relative calibration value of the sample to be tested under each characteristic condition, the relative calibration value can be normalized. Each characteristic condition here may include, for example, ten groups of incident angles and reflection angles, wherein any characteristic condition, i.e., one of the ten groups of incident angles and reflection angles, can be expressed as ( ).

[0036] In some embodiments, the normalized measurement value of the sample to be tested can be expressed by the following formula:

[0037] In the formula, is the normalized measurement value of the sample to be tested, for( ) is the calibration value under characteristic conditions.

[0038] Step 140: Determine the absolute calibration value of the sample to be tested under the characteristic condition based on the value of the standard diffuse reflection plate under the characteristic condition.

[0039] Specifically, under this characteristic condition ( ) Absolutely calibrate the sample to be tested to obtain the absolute calibration value of the sample to be tested under the characteristic condition. Step 140 specifically includes: Step 141, performing absolute value calibration on the signal current ratio of the sample to be tested and the standard diffuse reflection plate, respectively, to obtain an absolute signal current ratio; Step 142, based on the absolute signal current ratio and the value of the standard diffuse reflection plate under the characteristic condition, determine the absolute calibration value of the sample to be tested under the characteristic condition.

[0040] The formula is as follows:

[0041] In the formula, C abs sample Yes C sample The absolute signal current ratio of the sample to be tested obtained after absolute value calibration, C abs ref Yes C ref The absolute signal current ratio of the standard diffuse reflector obtained after absolute value calibration, It is a standard diffuse reflector in ( ) is measured under characteristic conditions using an absolute calibration device.

[0042] It should be noted that the characteristic conditions in step 140 are the same as those in step 130, that is, ( ) have the same value.

[0043] Step 150, determining the BRDF calibration value of the sample to be tested based on the normalized measurement value of the sample to be tested and the absolute calibration value under the characteristic condition.

[0044] Specifically, after obtaining the normalized measurement value of the sample to be tested and the absolute calibration value under the characteristic condition, the BRDF calibration value of the sample to be tested can be determined by the following formula:

[0045] In the formula, For the sample to be tested in ( ) BRDF calibration value under characteristic conditions, is the normalized measurement value of the sample to be tested, It is a standard diffuse reflector in ( ) is the value under characteristic conditions.

[0046] The method provided by the embodiment of the present invention calculates the normalized measurement value of the sample to be measured and the absolute calibration value under any characteristic condition through the value of each characteristic condition of the standard diffuse reflection plate calibrated on the absolute calibration device, thereby obtaining the BRDF calibration value of the sample to be measured. This method is for any BRDF measurement device, does not require it to have a strict absolute measurement function, and only relies on a standard diffuse reflection white plate with a one-to-one corresponding calibration value in its sample measurement space, and can simply and accurately achieve accurate and reliable measurement of the BRDF value of the measurement sample.

[0047] The measurement system of the BRDF reflection space distribution calibration value provided by the present invention is described below. The measurement system of the BRDF reflection space distribution calibration value described below and the measurement method of the BRDF reflection space distribution calibration value described above can be referenced to each other.

[0048] Based on any of the above embodiments, Figure 2 is a schematic diagram of the structure of the measurement system of the BRDF reflection space distribution calibration value provided by the present invention, such as Figure 2 As shown, the system includes: An absolute calibration device 210, used to calibrate the value of the standard diffuse reflection plate under various characteristic conditions; BRDF measuring device 220, used to obtain the signal current ratio of the sample to be tested and the standard diffuse reflection plate under various characteristic conditions; Processor 230 is used to determine the relative calibration value of the sample to be tested under each characteristic condition based on the value of the standard diffuse reflection plate under each characteristic condition calibrated on the absolute calibration device; normalize the relative calibration value based on the value of any one of the characteristic conditions to obtain the normalized measurement value of the sample to be tested; determine the absolute calibration value of the sample to be tested under any one of the characteristic conditions based on the value of the standard diffuse reflection plate under any one of the characteristic conditions; determine the BRDF calibration value of the sample to be tested based on the normalized measurement value of the sample to be tested and the absolute calibration value under any one of the characteristic conditions.

[0049] The system provided by the embodiment of the present invention calculates the normalized measurement value of the sample to be measured and the absolute calibration value under any characteristic condition through the value of each characteristic condition of the standard diffuse reflection plate calibrated on the absolute calibration device, thereby obtaining the BRDF calibration value of the sample to be measured. The system does not require the BRDF measurement device to have a strict absolute measurement function, and can simply and accurately achieve accurate and reliable measurement of the BRDF value of the measurement sample by only relying on a standard diffuse reflection white plate with a one-to-one corresponding calibration value in its sample measurement space.

[0050] Figure 3 An example of a physical structure diagram of an electronic device is shown in FIG. Figure 3 As shown, the electronic device may include: a processor 310 , a communications interface 320 , a memory 330 and a communication bus 340 , wherein the processor 310 , the communications interface 320 , and the memory 330 communicate with each other via the communication bus 340 . The processor 310 can call the logic instructions in the memory 330 to execute a method for measuring the BRDF reflection spatial distribution calibration value, which includes: respectively obtaining the signal current ratio of the sample to be tested and the standard diffuse reflection plate under each characteristic condition; based on the signal current ratio and the value of the standard diffuse reflection plate under each characteristic condition calibrated on the absolute calibration device, determining the relative calibration value of the sample to be tested under the each characteristic condition; based on any calibration value under any characteristic condition among the relative calibration values, normalizing each relative calibration value to obtain a normalized measurement value of the sample to be tested; based on the value of the standard diffuse reflection plate under any characteristic condition, determining the absolute calibration value of the sample to be tested under any characteristic condition; based on the normalized measurement value of the sample to be tested and the absolute calibration value under any characteristic condition, determining the BRDF calibration value of the sample to be tested.

[0051] In addition, the logic instructions in the above-mentioned memory 330 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0052] On the other hand, the present invention also provides a computer program product, which includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the measurement method of the BRDF reflection spatial distribution calibration value provided by the above-mentioned methods, which includes: respectively obtaining the signal current ratio of the sample to be tested and the standard diffuse reflection plate under each characteristic condition; based on the signal current ratio and the value of the standard diffuse reflection plate under each characteristic condition calibrated on an absolute calibration device, determining the relative calibration value of the sample to be tested under the each characteristic condition; based on any calibration value under any characteristic condition among the relative calibration values, normalizing each relative calibration value to obtain the normalized measurement value of the sample to be tested; based on the value of the standard diffuse reflection plate under any characteristic condition, determining the absolute calibration value of the sample to be tested under any characteristic condition; based on the normalized measurement value of the sample to be tested and the absolute calibration value under any characteristic condition, determining the BRDF calibration value of the sample to be tested.

[0053] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to execute a method for measuring the BRDF reflection spatial distribution calibration value provided by the above-mentioned methods, the method comprising: respectively obtaining a signal current ratio of a sample to be tested and a standard diffuse reflection plate under each characteristic condition; determining a relative calibration value of the sample to be tested under each characteristic condition based on the signal current ratio and the value of the standard diffuse reflection plate under each characteristic condition calibrated on an absolute calibration device; normalizing each relative calibration value based on any calibration value under any characteristic condition among the relative calibration values ​​to obtain a normalized measurement value of the sample to be tested; determining an absolute calibration value of the sample to be tested under any characteristic condition based on the value of the standard diffuse reflection plate under any characteristic condition; determining the BRDF calibration value of the sample to be tested based on the normalized measurement value of the sample to be tested and the absolute calibration value under any characteristic condition.

[0054] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0055] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for measuring a BRDF reflection spatial distribution calibration value, characterized in that: include: Respectively obtain the signal current ratio of the sample to be tested and the standard diffuse reflection plate under various characteristic conditions; Based on the signal current ratio and the value of the standard diffuse reflection plate under each characteristic condition calibrated on the absolute calibration device, determine the relative calibration value of the sample to be tested under each characteristic condition; Based on any calibration value under any characteristic condition in the relative calibration values, normalizing each of the relative calibration values ​​to obtain a normalized measurement value of the sample to be tested; Determine the absolute calibration value of the sample to be tested under any of the characteristic conditions based on the value of the standard diffuse reflection plate under any of the characteristic conditions; Based on the normalized measurement value of the sample to be tested and the absolute calibration value under any characteristic condition, the BRDF calibration value of the sample to be tested is determined.

2. The method for measuring the BRDF reflection spatial distribution calibration value according to claim 1, characterized in that: The method of respectively obtaining the signal current ratio of the sample to be tested and the standard diffuse reflection plate under the characteristic conditions comprises: Respectively obtaining the measurement signal current value and the monitoring signal current value of the sample to be tested and the standard diffuse reflection plate under the above-mentioned characteristic conditions; The ratio between the measured signal current value and the monitored signal current value is taken as the signal current ratio.

3. The method for measuring the BRDF reflection spatial distribution calibration value according to claim 1, characterized in that: The step of determining the absolute calibration value of the sample to be tested under any of the characteristic conditions based on the value of the standard diffuse reflection plate under any of the characteristic conditions comprises: Performing absolute value calibration on the signal current ratio of the sample to be tested and the standard diffuse reflection plate respectively to obtain an absolute signal current ratio; Based on the absolute signal current ratio and the value of the standard diffuse reflection plate under any of the characteristic conditions, the absolute calibration value of the sample to be tested under any of the characteristic conditions is determined.

4. The method for measuring the BRDF reflection spatial distribution calibration value according to any one of claims 1 to 3, characterized in that: The characteristic conditions include: the incident light and the reflected light are in the same plane, and the coordinate position of the incident light irradiated on the sample to be tested is the same as the coordinate position of the reflected light emitted from the sample to be tested.

5. A measurement system for BRDF reflection spatial distribution calibration value, characterized in that: include: Absolute calibration device, used to calibrate the value of the standard diffuse reflector under various characteristic conditions; A BRDF measuring device is used to obtain the signal current ratio of the sample to be tested and the standard diffuse reflection plate under various characteristic conditions; A processor is used to determine the relative calibration value of the sample to be tested under each characteristic condition based on the value of the standard diffuse reflection plate under each characteristic condition calibrated on the absolute calibration device; based on the value of any characteristic condition among the characteristic conditions, the relative calibration value is normalized to obtain the normalized measurement value of the sample to be tested; Determine the absolute calibration value of the sample to be tested under any of the characteristic conditions based on the value of the standard diffuse reflection plate under any of the characteristic conditions; Based on the normalized measurement value of the sample to be tested and the absolute calibration value under any characteristic condition, the BRDF calibration value of the sample to be tested is determined.

6. The measuring system of BRDF reflection space distribution calibration value according to claim 5, characterized in that: The wavelength range of the measuring light source of the absolute calibration device covers the ultraviolet, visible and infrared bands.

7. The measuring system of BRDF reflection space distribution calibration value according to claim 5, characterized in that: The detector of the absolute calibration device meets the detection requirements of ultraviolet, visible and infrared bands.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the method for measuring the BRDF reflection spatial distribution calibration value as described in any one of claims 1 to 4 is implemented.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for measuring the BRDF reflection spatial distribution calibration value as described in any one of claims 1 to 4 is implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the method for measuring the BRDF reflection spatial distribution calibration value as described in any one of claims 1 to 4 is implemented.

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