130 results about "Bidirectional reflectance distribution function" patented technology

An apparatus for determining a bidirectional reflectance distribution function of a subject. The apparatus includes a light source for producing light. The apparatus includes sensing means for sensing the light. The apparatus includes means for focusing the light between the light source and the sensing means and the subject. The apparatus includes a computer connected to the sensing means for measuring the bidirectional reflectance distribution function of the subject from the light sensed by the sensing means. The apparatus can include only one CCD camera for sensing the light. The apparatus can include means for taking sub-measurements of the subject with light from the light source without any physical movement between sub-measurements. A method for determining a bidirectional reflectance distribution function of a subject.

The invention discloses a consistent lighting method under a falsehood-reality fused environment, comprising the following steps: shooting a high dynamic range image reflecting a real environment, of a small mirror-surface sphere in a real scene, and acquiring an environmental lighting map of the real scene; preprocessing the environmental lighting map of the real scene and surface reflection attributes of a virtual object; preprocessing the environmental lighting of the real scene to generate environment lighting on a unit small sphere under local coordinates corresponding to all normal vectors to obtain Haar wavelet coefficients of the environment lighting; preprocessing a bidirectional reflection distribution function to generate slices of the bidirectional reflection distribution function on the unit hemisphere under all sight directions to obtain Haar wavelet coefficients of the slices; and drawing a falsehood-reality fused environment, indexing the wavelet coefficients of the environment lighting and the slices of the bidirectional reflection distribution function according to a normal vector of an apex of the virtual object and the sight directions, calculating a vector product of the coefficients to obtain an apex drawing color, and meanwhile, accelerating by adopting GPU (Graphics Processing Unit). The consistent lighting method can be used for efficiently realizing afull-range environment lighting drawing effect under the falsehood-reality fused environment.

The invention discloses an indoor full-automatic BRDF (bidirectional reflectance distribution function) measurement device. The device comprises a support panel, a support platform is provided with a horizontal turntable, a sample table is mounted in a central through hole of the horizontal turntable, the horizontal turntable is equipped with a lens bracket on which a lens rotary arm is arranged,a lens rotary arm end is equipped with a spectrograph lens, an optical axis of the spectrograph lens always points to the centre of the sample table, the support platform is further equipped with an optical source guide rail on which an artificial optical source is arranged, the artificial optical source always points to the centre of the sample table. The BRDF measurement device can effectively improve the positioning precision, reduces the measurement period, and improves the optical source collimation and uniformity so as to effectively guarantee the measurement precision.

The invention provides a method for obtaining a leaf area index based on quantitative fusion and inversion of multi-angle remote sensing data and multi-spectral remote sensing data, which is characterized in that a coefficient of a bidirectional reflectance distribution function (BRDF) of a vegetation type of the best matching pixel level of the multi-angle remote sensing data and a surface reflectivity is adopted, a surface soil reflectivity profile is obtained based on best matching of the multi-spectral data, and a canopy radiation transmission model is driven to obtain the leaf area index with high accuracy and large-scope coverage based on the multi-spectral data. The invention has the advantages that: the ranges of wave bands of the multi-angle data and the multi-spectral data need not to be overlapped, and approximate treatment can be carried out by adopting the similarity of the bidirectional function of the available wave bands; the coefficient of the bidirectional reflectance function and the best matching vegetation type obtained based on the multi-angle data is relatively stable along with changes in the time and the space, time sequence data can be made into a background library to be used as input for inversion of the multi-spectral data, and thus the large-scale leaf area index with high time resolution can be obtained; and the best matching surface soil reflectivity profile obtained based on the multi-spectral data is relatively stable, and historical time sequence data can also be made into a background library. The method can be applied in crop growth monitoring, rapid estimation of crop yields and the like.

The present invention realizes a specular gloss simulation device which can accurately simulate, by using a Bidirectional Reflectance Distribution Function, specular glossiness of an image even if the image has a low density and low gloss. A specular gloss simulation device according to the present invention is for simulating specular glossiness by simulating a specular reflection light amount in each (other) geometry from a luminance measured in a given geometry of a sample having a base material and a colorant material layer formed on the base material. A specular gloss simulation device 100 is provided with a lower layer reflection light component calculating section 111 for calculating a lower layer reflection light component, which is reflected on a base material and travels through and out of a color layer, an internal reflection light component creating section 112 for creating an internal reflection light component, which is reflected from an interior of the colorant material layer, a surface reflection light component creating section 113 for creating a surface reflection light component, which is reflected on a surface of the colorant material layer, and a specular reflection light amount calculating section 114 for obtaining a specular reflection light amount of the sample by adding up the components thus created by each section.

The invention relates to a method for establishing a bidirectional reflectance distribution function (BRDF) prototype library based on multi-angular measurement. Through self-defining bidirectional anisotropic flat index (AFX) and iterative self-organizing ISODATA clustering algorithm, a theory and a method for establishing the BRDF prototype library based on BRDF feature mode are provided and are realized by using 69 groups of ground surface multi-angular measurement data and the history data (MCD43A) of global EOS ground surface verification core point. According to the theory and the method, the conventional method for establishing a BRDF database based on the ecological form of ground surface is abandoned, the BRDF prototype library is different from the global pixel-to-pixel BRDF database of MODIS (Moderate-resolution Imaging Spectroradiometer) in the service operation at present; and is small in volume, simple and convenient to construct and easy to operate, and is applicable for other airborne and spaceborne multi-angular measurement data of ground surface. In the technical field of spatial information, the method particularly has theoretical and application values for extracting BRDF prior knowledge to invert ground surface parameters in the aspect of quantitative remote sensing.

The invention relates to a measuring device of a continuous spectrum bidirectional reflectance distribution function, belonging to the fields of spectroscopy, computer graphics and machine vision and solving the problem that the traditional device can not measure the continuous spectrum BRDF (Bidirectional Reflectance Distribution Function) within a visible light wave band. A center point of a sample ring is a rotation center, and the sample ring is arranged on a sample horizontal and vertical direction rotating bracket; the sample horizontal and vertical direction rotating bracket is used for driving the sample ring to rotate on a horizontal surface and a vertical surface perpendicular to the horizontal surface by taking the rotation center as the center point; an optical fiber probe is arranged on a detector position regulation bracket, and a light path points at the rotation center; the detector position regulation bracket is used for driving the optical fiber probe to rotate on the horizontal surface by taking the rotation center as the center point and driving the optical fiber probe to make a one-dimensional linear motion with a motion trail penetrating through the rotation center; the signal output end of the optical fiber probe is connected with the input end of a spectrograph; a rotation controller is used for controlling the rotation of the sample horizontal and vertical direction rotating bracket and the detector position regulation bracket; a PC (Personal Computer) is connected with the spectrograph and the rotation controller; and light beams of a light source assembly are irradiated on the sample ring. The measuring device is used for measuring the continuous spectrum BRDF within the visible light wave band.

The invention provides a luminosity diagram-based geometry and surface material reconstructing method. The method comprises the following steps of: (1) segmenting a material, constructing an initialized material weight figure, establishing Diffuse Albedo; (2) estimating a surface normal vector diagram; (3) iterating and solving a normal vector by using an Alternating-Constrained-Least-Square method and constructing a bidirectional reflectance distribution function (BRDF) material substrate; and (4) enhancing a depth filed. On the basis of a normal vector diagram, the least square surface depth information is obtained by a Poisson equation. By the method, different material areas and material attributes and the surface depth information of an object in a picture can be recovered automatically from a group of picture sequences with known light conditions reliably; and the object is subjected to three-dimensional reconstruction rapidly.

The invention discloses a material high realistic rendering algorithm based on bidirectional reflectance distribution function (BRDF) measured data. The material high realistic rendering algorithm includes the following steps: (1) collecting measured data of material light and fitting a rendering model of the material according to the measured data, (2) exerting high dynamic environment light on the rendering model, and (3) collecting the environment light at a random discretization direction in the rendering process, and rendering the material through utilization of the rendering model in the step (1). The material high realistic rendering algorithm based on the BRDF measured data utilizes sampling data of the material of real automobiles, fits the rendering model for material, uses the high dynamic environment light to illuminate the rendering model, and obtains a rendering effect of the material with a good realistic feeling.

The invention relates to a system for measuring surface bidirectional reflectance distribution. The system is characterized in that a hemi-parabolic reflector is arranged on the surface of a sample to be measured; a light source system is arranged on one side of a main shaft in the center of the hemi-parabolic reflector, and is opposite to the inner parabolic surface; an imaging system is arranged on a shaft which is intersected with and vertical to the main shaft, and is positioned above a plain shaft; a beam splitter is arranged between the light source system and the hemi-parabolic reflector; the mirror surface of the beam splitter forms a 45-degree angle with the plain shaft; the light source system consists of a light source, a semicircular light source seat and a sliding rail; the radius of the sliding rail is twice of focal distance of a parabolic reflector, and is embedded in the upper edge of the semicircular light source seat; the light source is arranged on the semicircle sliding rail; the plain shaft is parallel to the main shaft; the beam splitter is a half-silvered mirror; the inner surface of the hemi-parabolic reflector is a reflecting coating; and the caliber of the parabolic surface is more than fourfold focal distance. The system can complete measurement of surface bidirectional reflectance distribution in short time, and has smaller repeatability error.

A computer-implemented process for generating a bidirectional reflectance distribution function (BRDF) of a gonioapparent material containing effect flake pigments in a solid medium using limited measurement data, comprising the following steps: (A) acquiring and inputting into a computing device (1) photometric data and (2) the refractive index of the solid medium of the gonioapparent material; (B) converting any non-linear photometric data from step A) above to linear photometric data; (C) using the illumination angle and the reflective scattering angle associated with the linear photometric data and the refractive index of the medium to calculate corresponding effect flake angles; (D) fitting the linear photometric data and the effect angle data with an equation; (E) calculating the corresponding effect flake angle needed to calculate the BRDF being generated in step (F); and (F) generating the BRDF from the corresponding effect flake angle from step (E) and the equation developed in step (D).

This disclosure is directed to a method for matching color and appearance of an object. The method comprise the step of generating a bidirectional reflectance distribution function (BRDF) of a gonioapparent material containing effect flake pigments in a solid medium using limited measurement data.

The invention discloses an infrared reflection characteristic simulation method based on GPU (graphics processing unit) programming, and mainly solves overcomes the defects of low physical realism reality sense and poor instantaneity of reflection effect simulation in the traditional prior art. The realization process of the infrared reflection characteristic simulation method is as follows: obtaining a direct solar radiation texture D, a sky background radiation texture S, an atmosphere path radiation texture L and an atmosphere transmittance texture T in a file of which the suffix is DDS (direct draw surface); obtaining a material parameter M required for calculating BRDF (bidirectional reflectance distribution function); according to a simplified Schlick BRDF reflection model, calculating the a reflection amount E1 on the direct solar radiation and the a reflection amount E2 on the sky background radiation by different pixels via the material parameter M; writing the DDS texture into a texture unit of a material script to generate the material script capable of generating simulation infrared reflection effect; finishing the analysis and the compiling of the material script by the GPU, and loading into a video memory; and operating the script programs to simulate the infrared reflection effect in real time. The infrared reflection characteristic simulation method based on the GPU programming has the advantages of strong simulation sense of reality and high instantaneity, and can be used for developing, testing and evaluating an infrared imaging system.

The invention provides a cross radiation calibration method and system for a large observation angle sensor. The method comprises steps that a to-be-calibrated image and a reference image are registered, random sampling of each set of corresponding wave bands of the to-be-calibrated image and the reference image is respectively carried out to acquire corresponding calibration points; for each wave band, cross calibration for each pair of calibration points is carried out respectively, a BRDF adjusting coefficient is established as a ratio of a surface bidirectional reflection distribution function of the to-be-calibrated image and a surface bidirectional reflection distribution function of the reference image, and processing is carried out in an iteration mode; for each wave band, points with average mean values greater than a preset threshold are deleted from the cross calibration result, averaging is carried out, and a final radiation calibration coefficient is acquired. The method is advantaged in that BRDF values of the to-be-calibrated image and the reference image can be respectively calculated without a complex model, calculation is simple and stable, strong operationality is realized, and an error caused by introducing auxiliary data for BRDF calculation and influence of abnormal calibration points on the result can be further avoided.

The invention discloses a novel bidirectional reflectance distribution function measuring device. A light source 1 is fixed and illuminates perpendicularly and downwards, a sample supporting component is a six-axis manipulator, a probe rotation driving unit 5 drives a detector probe 2 to rotate semi-circularly in a vertical plane above a horizontal plane, the six-axis manipulator 3 is combined with a perpendicular rotating device, a sample 4 and a detector move in a combination manner, the pointing direction and the azimuth angle of a normal line of the illuminated sample and the pointing direction of the detector probe are changed, and incident light and a detection direction in a hemisphere space are accurately positioned relative to the center azimuth angle and the pitch angle of the sample.

The invention provides a design method of a light-emitting diode (LED) even-illumination light source based on a high-diffuse-reflection-rate free-form surface. A general mathematical model of a free-form surface diffuse reflection surface for secondary light distribution is built by utilizing a bidirectional reflection distribution function (BRDF) of a high-diffuse-reflection-rate surface according to light-emitting characteristics of the LED light source. The mathematical model is utilized to write a nonlinear algebraic equation set by combining specific requirements for target illumination areas and the irradiance distribution in an actual application occasion, and a numerical method is utilized to conduct calculation to obtain a surface type outline of the diffuse free-form surface. The LED indirect light source based on the high-diffuse-reflection-rate free-form surface is compact in system structure, high in illumination evenness and capable of being used in the fields of color vision measurement, indoor illumination, projector devices and the like requiring high-evenness illumination conditions and has good application prospects.

The invention discloses a remote sensing image terrain standardization method. In a Ross Thick-Li Sparse linear kernel driver model, slope and orientation are introduced into a Ross volume scattering kernel function and a Li geometrical optical kernel function to establish a mountain BRDF (Bidirectional Reflectance Distribution Function) model; on the basis of a conventional remote sensing image terrain standardization result, an assumption of the earth surface about a Lambertian reflectance characteristic is changed, and the mountain BRDF model is introduced to maximally reduce the influence of a change in the BRDF shape of a complicated topographical region; atmospheric parameters at the border crossing moment of a satellite image are obtained by taking MODIS (Moderate Resolution Imaging Spectroradiometer) water vapor and aerosol atmosphere products as terrain standardization model parameters, so that the influence of optical factors of the atmosphere is eliminated. According to the method, radiometric distortion of a remote sensing image caused by optical properties of the atmosphere is eliminated, and in addition, radiometric distortion caused by factors such as terrain shielding and BRDF properties of the earth surface is effectively eliminated, so that the real reflectivity of the earth surface is obtained.

The invention relates to a method for improving a business nuclear drive bidirectional reflectance distribution function (BRDF) model hot spot. The method comprises the following steps: a new volume scattering nucleus considering the hot spot change is put forward through carrying out the hot spot calibration on the volume scattering nucleus of a conventional MODIS business nucleus drive BRDF model RTLSR, an RTCLSR model generated by the linear combination of the nucleus with an original geometrical optics nucleus has preferable fitting capability to the hot spot, but the fitting precision in the other observation directions is not influenced, a POLDER-3/BRDF database and onboard CAR data are used to carry out calibration and verification on the hot spot parameters of the RTCLSR model, the new RTCLSR model is available to study the change of the hot spot effect with earth surface category, NDVI and a solar zenith angle, meanwhile, the new model maintains the linear form of an original model very well, and the complexity of model calculation is not greatly increased, so that a new algorithmic base and a solution provided for the MODIS BRDF/ albedo business product up-gradation is made into possible. The method for improving the business nuclear drive bidirectional reflectance distribution function (BRDF) model hot spot has significant application value in the technical field of spatial information, in particular to the aspect of quantitative remote sensing.

A BRDF (bidirectional reflectance distribution function) -based real-time subsurface scattering rendering method includes the following steps: firstly, decomposing an illumination model into a Phone model, a scattering model and compensated illumination; secondly, improving a subsurface scattering model: adopting the BRDF method to approximate single subsurface scattering in subsurface scattering, and by simplifying an integral, simplifying a great deal of calculation load brought by the conventional illumination model to increase the rendering efficiency; and finally, rendering subsurface scattering in real time: by introducing the idea of deferred shading and adopting the GPU (graphics processing unit) technology, rendering subsurface scattering in an image space in real time is completed. The BRDF-based real-time subsurface scattering rendering method adopts the BRDF approximation method, realizes the real-time property of subsurface scattering rendering, and enhances the calculation performance while guaranteeing realistic rendering.