131 results about "Bidirectional reflectance distribution function" patented technology

An apparatus for determining a bidirectional reflectance distribution function of a subject. In one embodiment, the apparatus includes a light source for producing light. The apparatus includes means for measuring the bidirectional reflectance distribution function of the subject from multiple locations simultaneously with the light. A method for determining a bidirectional reflectance distribution function of a subject.

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.

An apparatus for determining a bidirectional reflectance distribution function of a subject. In one embodiment, the apparatus includes a light source for producing light. The apparatus includes means for measuring the bidirectional reflectance distribution function of the subject from multiple locations simultaneously with the light. 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 invention discloses an integrated modeling method for an infrared radiation characteristic of a complicated target. A bidirectional reflection distribution function model of infrared radiation on the surface of the complicated target and an infrared radiation model of non-uniform tail flame gas are considered based on a radiometry spectral ray tracking method; in a ray tracking process, the pixel on the focal plane of a detector is sampled, thus generating ray bundles, and an intersection between each ray and the complicated target in a scene is calculated; a radiation reflection value of each intersection is calculated, and the radiation brightness obtained by all the rays of the pixel is subjected to sampling and reconstruction, thus obtaining the radiation brightness with a spectral form at the pixel of the detector; finally, a required infrared spectrum band is integrated, thus obtaining a target infrared radiation characteristic value received by the detector. According to the integrated modeling method, the spectral ray tracking method runs through the whole solving process, and a solving model suitable for a ray tracking form is constructed, so that the integrated modeling method is suitable for infrared radiation characteristic simulation of a tail-flame-containing complicated target aircraft under a specific flying state.

The invention relates to an indoor hyperspectral bidirectional reflectance distribution function (BRDF) determining system, which comprises a light source area, a hyperspectral auxiliary brightness gauge adjusting area, a carrier stage area and a base which is horizontally placed; the light source area comprises a light source, a light source space adjusting valve, a light source supporting rod and a semi-arc slide rail, wherein the light source is hinged with the circular center of the semi-arc slide rail which is fixed on the side surface of the base through the light source supporting rod; the hyperspectral auxiliary brightness gauge adjusting area comprises an auxiliary brightness gauge, a space adjusting device, a quarter-arc slide rail and a hollow rotary disc, wherein the carrier stage area is arranged on the center of the base, and the hollow rotary disc is fixed on the center of the base; an optical axis of the light source always points to the center of the hollow rotary disc; and both the light source and the auxiliary brightness gauge are powered on. The indoor hyperspectral BRDF determining system has beneficial effects that: shade can be eliminated, the measuring precision can be improved, and the flexibility of the measuring range can be improved; and the rotation of the carrier stage can introduce the azimuth angle characteristic of the BRDF light source, so the completeness of the BRDF determination can be enhanced.

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 method for dynamic sea surface laser pulse wave beam echo simulation. The method for dynamic sea surface laser pulse wave beam echo simulation comprises the following steps that according to a sea spectrum statistic model, a dynamic sea surface is generated by means of the reverse-FFT technology, and the parameters such as the wind speed, the wave height and the sea wave period are considered through the model; space energy distribution and the pulse shape of each emitted laser wave beam are measured, space-time distribution of any laser wave beam is obtained through fitting, and section spatial light intensity distribution at any distance is determined based on energy conservation; a laser radar wave beam back scattering echo radar equation is established based on the radiometry, rough surface processing is conducted on a water surface element, and the water surface element is expressed through a bidirectional reflection distribution function; drawing, coloring, rendering, real-time animation, hidden-line elimination and clipping of the scene are completed based on a computer graphic base OpenGL. The method for dynamic sea surface laser pulse wave beam echo simulation can be applied to different sea condition model machine dynamic intersection virtual experiments, facilitate development of sea surface pulse echo scattering mechanism study, and save a large amount of cost.

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 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 method and a system for measuring a multispectral bidirectional reflectance distribution function of a sample of any shape. The system comprises a spherical bracket, a sample bracket, a light source array unit, a projector array unit, an imaging spectrometer array unit and a central control server. The method comprises the following steps: projecting a Gray code image to a to-be-measured sample by virtue of the projector array unit; projecting collimated light beams in different directions to the to-be-measured sample by virtue of the light source array unit; acquiring a multispectral image of the to-be-measured sample by virtue of the imaging spectrometer array unit; processing the Gray code image on the surface of the to-be-measured sample by virtue of the central control server, thereby obtaining the three-dimensional coordinate and normal of each sampling point on the to-be-measured sample; and processing the multispectral image under the illumination condition in different directions, thereby obtaining the multispectral bidirectional reflectance distribution function of the to-be-measured sample. According to the method and the system disclosed by the invention, the multispectral bidirectional reflectance distribution function data of the to-be-measured sample of any shape can be measured.

The invention discloses a BRDF quick measurement device based on hemisphere array detection. The BRDF quick measurement device consists of a laser, a fiber beamsplitter, a light power meter, a two-dimensional adjustment and laser collimation mechanism, a fully-closed hemisphere darkroom, an array photoelectric detector, a data collecting and processing system and an upper computer. According to the invention, complicated mechanical structures and electromechanical control systems are omitted, so that the structure is simple and the operation is convenient; the hemispherical fully-closed design is provided with the darkroom experiment environment, so that the system environmental adaptability is improved; through intensive array detection in the hemispherical space, the bidirectional reflectance distribution functions of all sampling angles of the reflective hemispherical space of a material to be tested can be measured quickly at one time within 2 seconds, so that the measurement efficiency is improved; complicated optical systems are not provided, the simple universal model that only the photoelectric detector and a high-speed digital circuit acquisition module are adopted is used for quick collecting and processing of multiple signals, so that the cost is relatively low.

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).

The invention discloses an aerosol optical thickness inversion method, solving problems that the existing method is greatly affected by ground angle effect and has poor stability when being applied toan AHI sensor. The method comprises steps of removing pixels of inland water body, ice / snow and cloud in reflection rate of a satellite band; establishing a bidirectional reflectance distribution function parameter database based on MCD19A3 historical data of a MODIS product; dynamically calculating ground reflection rate according to a RTLS model, and obtaining a ground reflection rate initial value; constructing a spectral conversion model, and converting the ground reflection rate initial value into a ground reflection rate conversion value; for a single scattering albedo, removing data ofsand and dust weather, calculating average value quarterly, and establishing a 6S search table; and searching the 6S search table to obtain surface reflection rate analog value and aerosol optical thickness that are corresponding, and interpolating in the aerosol optical thickness, so as to obtain an aerosol optical thickness inversion result. The method can lower angle effect and region limitation of AOD inversion.

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.

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).

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 system and method for more accurately generating the surface normal calibration maps φ(AoLP) and θ(DoLP,φ) to compensate for structured scene reflections for 3-D polarimetric imaging. This is accomplished using a microfacet scattering model to develop the functional form of a polarized bidirectional reflectance distribution function (BRDF) of the object surface. The ambient radiance is ray traced to the BRDF to create the calibration maps φ(AoLP) and θ(DoLP,φ), which may be combined into a single calibration map θ(DoLP, AoLP). These maps are applied to the AoLP and DoLP images to compute an array of surface normals, which are then mapped to form a 3-D image of the object.

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.

The invention discloses a modeling method of rough surface microwave band bidirectional reflectance distribution function. The modeling method comprises the following steps of: generating a rough surface by a Monte Carlo method according to power spectral density function of rough surface; calculating unit radar cross section sigma 0 of the rough surface by a moment method; obtaining a bidirectional reflectance distribution function of the rough surface according to the relation between the rough surface scattering coefficient and the bidirectional reflectance distribution function; modeling a five-parameter empirical model according to the obtained bidirectional reflectance distribution function; selecting optimal standard according to the model parameters, optimizing the parameters of the five-parameter model to obtain empirical parameters; according to the empirical parameters obtained by optimization, modeling a rough surface bidirectional reflectance distribution function through the five-parameter empirical model. Compared with the prior art, the modeling method provided by the invention has the advantages of fast optimization speed, high modeling precision and strong universality, and can be used for study on features of rough surface microwave band bidirectional reflectance distribution function.