67 results about "Subsurface scattering" patented technology

Techniques are described for modeling layered facial reflectance consisting of specular reflectance, single scattering, and shallow and deep subsurface scattering. Parameters of appropriate reflectance models can be estimated for each of these layers, e.g., from just 20 photographs recorded in a few seconds from a single view-point. Spatially-varying specular reflectance and single-scattering parameters can be extracted from polarization-difference images under spherical and point source illumination. Direct-indirect separation can be employed to decompose the remaining multiple scattering observed under cross-polarization into shallow and deep scattering components to model the light transport through multiple layers of skin. Appropriate diffusion models can be matched to the extracted shallow and deep scattering components for different regions on the face. The techniques were validated by comparing renderings of subjects to reference photographs recorded from novel viewpoints and under novel illumination conditions. Related geometry acquisition systems and software products are also described.

A face is scanned to obtain a three-dimensional geometry of the face, images are also acquired of the face, and subsurface scattering of the face is measured. A translucency map is determined from the subsurface reflectance. A total surface reflectance and a normal map are estimated from the three-dimensional geometry and the images, and diffuse reflectance is estimated using the total reflectance. An albedo map is determined from the diffuse reflectance. The diffuse reflectance is subtracted from the total reflectance to obtain a surface reflectance. A set of bi-directional reflectance functions is fitted to the surface reflectance. Then, the set of bi-directional reflectance distribution functions, the albedo map, and the translucency map are combined to form a skin reflectance model of the face.

The invention relates to an in vivo detection method capable of realizing human body in vivo detection and an in vivo detection system employing the in vivo detection method. The in vivo detection method comprises steps that the structured light is utilized to irradiate a to-be-detected object; the first face image data of the to-be-detected object irradiated by the structured light is acquired; based on the first face image data, detection parameters indicating a subsurface scattering degree of the structured light on a face of the to-be-detected object are determined; based on the detection parameters and the pre-determined parameter threshold, whether the to-be-detected object is a living body is determined.

The invention discloses a physical method based on environment mapping for simulating human skin subsurface scattering. The method comprises steps that, a legendre formula is utilized to project and disintegrate an illumination integration equation in a to-be-simulated scene to acquire a luminance value of each pixel; the luminance value of each pixel is multiplied with an overflow color value to acquire a scattering value of each pixel at a back light face. The physical method based on environment mapping for simulating human skin subsurface scattering solves problems of large data processing workload, large occupation storage space and low processing efficiency existing in the prior art and has advantages of small data processing workload, small occupation storage space and high processing efficiency.

Embodiments are directed to modifying an existing scheme for providing translucent illumination in order to take account of subsurface scattering. The color of a selected point of a translucent object can be determined using existing methods. The existing methods need not take subsurface scattering into account. Then, a contribution to the color at the selected point due to subsurface scattering may be calculated. The contribution due to subsurface scattering may be calculated based on a photon map. Embodiments of the invention also include the use of different types of photon maps. In some embodiments, a standard photon map may be used. In other embodiments, a photon map may be defined in a manner similar to a depth map. Thus, the entries of a photon map may be defined in terms of an angle from a light source and a distance between an object's surface and a light source.

A “light field morpher,” as described herein, provides a computationally efficient system and method for image-based three-dimensional (3D) morphing and texture transfer of 3D objects by morphing “light fields” or “lumigraphs,” associated with source and target 3D objects. The light field morpher is applicable to morphing of objects having either or both Lambertian, or non-Lambertian surfaces, including surfaces having complex properties such as fur, subsurface scattering, and hypertextures, without the need for object modeling, or otherwise recovering detailed object geometry. Light field morphing begins by first specifying corresponding 2D and 3D feature elements, such as, “feature lines,”“feature polygons,” and “background edges,” in the input light fields representing the source and target light fields. Once the feature elements have been specified, “ray-space warping” of both light fields then warps those light fields to produce feature alignment. These warped light fields are then blended to produce a light field morph.

Techniques are provided for at least modeling any one of mesostructure shadowing, masking, interreflection and silhouettes on a surface, as well as subsurface scattering within a non-homogeneous volume. Such techniques include, at least, acquiring material parameters for a material sample, determining irradiance distribution values for the material sample, synthesizing the material sample onto a mesh of an object. The synthesized object may then be rendered by one of plural rendering techniques.

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 real-time realistic drawing method of a human heart. The method comprises the steps of effectively drawing the surface and sub-surface effects by the texture space sub-surface drawing method and the semitransparent transmission method; combining a concave-convex map and a Kelemen/ Szirmay-Kalos lighting model, so as to achieve the effect the heart surface is covered with mucus; combining sub-frame scattering, mucus coverage and other foundation effect of the heart surface to obtain the heart surface drawing effect. The experiment result shows that the real-time realistic drawing method of the human heart is relatively high in drawing efficiency and realistic performance.

The invention provides a real-time global illumination method for a sub-surface scattering object on the basis of the radiosity, which is mainly divided into three steps of: 1) pre-calculating: pre-calculating an energy transmission matrix of a scene by the traditional approximate dipole model and the radiosity, and storing in a sparse matrix mode; 2) calculating an energy transmission process by a quick sparse matrix library of a GPU (Graphics Processing Unit), and obtaining energy acquired by each surface patch; and 3) obtaining the final global illumination effect by a quick photon collection algorithm. On the basis of the certain pre-calculation basis, the real-time global illumination effect for the sub-surface scattering object can be obtained.

A method for determining a snow covered surface condition of a path of travel. A beam of light is emitted at a surface of the path of travel by a light emitting source. An image of a path of travel surface is captured by an image capture device. The image capture device is mounted on the vehicle and captures an image in a downward direction. The captured image captures the beam of light emitted on the path of travel surface. Analyzing a subsurface scattering of the light generated on the path of travel surface by a processor. A determination is made whether snow is present on the path of travel. A snow covered path of travel surface signal is generated in response to the identification of snow on the path of travel.

The invention discloses a surface and subsurface integrated confocal microscopic measurement device and a surface and subsurface integrated confocal microscopic measurement method. The surface and subsurface integrated confocal microscopic measurement comprises an annular light illumination module, an annular light scanning module, a reflective confocal detection module and a dark field confocal detection module, wherein the annular light illumination module comprises a laser, a beam expander, a polarizing film I, a polarizing beam splitting film, a quarter-wave plate, a conical lens and a plane mirror; the annular light scanning module comprises a transflective film I, a two-dimensional scanning galvanometer, a scanning lens, a tube lens, an objective lens and a to-be-detected sample; thereflective confocal detection module comprises a transflective film II, a polarizing film II, a focusing lens I, a pinhole I and a camera I; and the dark field confocal detection module comprises a diaphragm, a polarizing film III, a focusing lens II, a pinhole II and a camera II. By means of illumination beam shaping and complementary aperture shielding detection, the surface and subsurface integrated confocal microscopic measurement device effectively separates a sample surface reflection signal and a subsurface scattering signal, can obtain three-dimensional distribution information of defects such as nanoscale surface scratches, abrasion, subsurface cracks and bubbles at the same time, and has a surface and subsurface defect integrated detection function.

The invention discloses a body rendering method of a semitransparent material. The method comprises the following steps: step one, obtaining light source attribute data and material parameter data of a semitransparent module body; step two, for each light color spectrum, through combination with the light source attribute data and the material parameter data of the semitransparent module body, generating a body light quantity model; and step three, based on a conventional light projection algorithm, an influence exerted by voxels around a sampling point on the sampling point is added, and a rendering formula of the semitransparent module body is obtained. The invention also discloses a body rendering system of a semitransparent material, comprising structures of such three portions, i.e., a data collection unit, a body light quantity model generation unit and a rendering unit. According to the invention, little extra memory is consumed based on a conventional light projection three-dimensional rendering algorithm, real-time subsurface scattering simulation is realized, and the problem of too much consumption of time and memory in conventional simulation subsurface scattering is well solved.

The invention discloses a dark field confocal microscopic measurement device and method based on polarization autocorrelation. The device comprises a polarization annular light illumination module, apolarization annular light scanning module and a confocal polarization detection module. A sample surface reflection signal and a subsurface scattering signal are effectively separated through illumination beam shaping and complementary aperture shielding detection, three-dimensional distribution information of nanoscale surface scratches, abrasion, subsurface cracks, bubbles and other defects canbe obtained at the same time, and the function of integrated detection of surface and subsurface defects is achieved. Meanwhile, polarity scattering and autocorrelation cumulant difference of adjacent observation points are generated by exciting single-wave vector illumination light fields in different directions by utilizing asymmetry of a sample structure so that super-resolution measurement isrealized. The device and the method have the advantage that nanoscale subsurface three-dimensional defect detection can be achieved.

The invention discloses a method and device for rendering the subsurface scattering effect. According to the scheme, after a target object to be rendered is determined, and aiming at each light emission point on a light emission surface in the target object, a plurality of target light incidence points are sampled from a light incidence surface; for each target light incidence point corresponding to the light emission points, based on the target distance between the target light incidence points and the target light emission points, the illumination intensities of the target light illumination intensity points is subjected to index attenuation, and attenuated illumination intensities is obtained; for each light emission point, multiple attenuated illumination intensities corresponding to the light emission points are summed up, and the illumination intensities of the light emission points are obtained; the subsurface scattering effect of the target object is rendered according to the illumination intensities of the light emission points on the light emission face. According to the scheme, the truthfulness of the rendered subsurface scattering effect of the object in a picture can be improved.

Disclosed herein are an image processing apparatus and an image processing method for realistically expressing an object. The image processing apparatus includes a volume data generator configured to generate volume data using received signals of an object, and a volume rendering unit configured to perform volume rendering using the volume data to acquire a projection image, and apply a subsurface scattering effect according to virtual lighting information, to the projection image with respect to a user's viewpoint to produce a final image.

The invention discloses a dark field confocal microscopic measurement device and method based on polarization autocorrelation. The device comprises a polarization annular light illumination module, apolarization annular light scanning module and a confocal polarization detection module. A sample surface reflection signal and a subsurface scattering signal are effectively separated through illumination beam shaping and complementary aperture shielding detection, three-dimensional distribution information of nanoscale surface scratches, abrasion, subsurface cracks, bubbles and other defects canbe obtained at the same time, and the function of integrated detection of surface and subsurface defects is achieved. Meanwhile, polarity scattering and autocorrelation cumulant difference of adjacent observation points are generated by exciting single-wave vector illumination light fields in different directions by utilizing asymmetry of a sample structure so that super-resolution measurement isrealized. The device and the method have the advantage that nanoscale subsurface three-dimensional defect detection can be achieved.

The invention discloses a point cloud based method for calculating emergent irradiance of a sub-surface scattering object. The method comprises the steps of (1): sampling the surface of the sub-surface scattering object, then performing direct illumination calculation on a sampling point on the surface of the sub-surface scattering object to form a point cloud sampling point, and organizing the point cloud sampling point into a point cloud tree for storage; and (2): performing a light ray tracing and rendering process for rendering, wherein a cross point of each light ray and a scene containing a plurality of three-dimensional objects is a coloring point; when the coloring point falls on the sub-surface scattering object, traversing the point cloud tree to obtain a tree cut associated with the emergent irradiance of the current coloring point, performing integration on the incident irradiance of the current coloring point by each node on the tree cut, and performing calculation according to a sub-surface scattering function to obtain the emergent irradiance of the current coloring point in any direction.

The invention discloses a screen-space-based method for simulating the real skin of a figure through sub-surface scattering. The method mainly includes the steps of conducting filtration and screening on a finger skin object to be rendered and other objects in a scene; rendering the skin of the figure first time to obtain Alpha mixing to obtain a mixed image; rendering the scene second time to obtain a semi-transparent effect image for a thinner part of the skin; stacking the semi-transparent image with the mixed image to obtain a final rendering effect image. By means of the screen-space-based method for simulating the real skin of the figure through sub-surface scattering, the shortcomings that in the prior art, the rendering difficulty is large, the drawing accuracy is poor and the image effect is untruthful can be overcome; the screen-space-based method has the advantages of being small in rendering difficulty, good in drawing accuracy and real in image effect.

The invention discloses a surface and subsurface integrated confocal microscopic measurement device and method. The device comprises an annular light illumination scanning module, a dark field confocal detection module and a reflection confocal detection module, wherein the annular light illumination scanning module comprises a laser, a beam expanding lens, a first polaroid, a first diffraction type flat plate conical lens, a second diffraction type flat plate conical lens, a beam splitting prism, an objective lens and a three-dimensional displacement table; the reflection confocal detection module comprises a reflector with a light through hole, a polarizing film I, a focusing lens I, a pinhole I and a camera I; and the dark field confocal detection module comprises a polarizing film II, a focusing lens II, a pinhole II and a camera II. Through illumination beam shaping and complementary aperture shielding detection, a sample surface reflection signal and a subsurface scattering signal are effectively separated, three-dimensional distribution information of defects such as nanoscale surface scratches, abrasion, subsurface cracks and bubbles can be obtained at the same time, and the surface and subsurface defect integrated detection function is achieved.