89 results about "Visibility function" patented technology

A method and apparatus for rendering shadows. A pre-rendering process implements a two dimensional array or map of depth-based functions, such as a visibility function in z. During rendering of an object scene, these functions are accessed via lookup operations to efficiently determine the function value for a sample point at a given depth. The use of visibility functions allows for partial light attenuation effects. Each visibility function is computed by filtering multiple transmittance functions obtained by casting sample rays from a light source onto an object scene. The visibility function is implemented as a sequence of vertices. Colored shadows are modeled by vertices comprising a depth value and separate visibility function values for red, green, and blue light at a given depth value. Compression is achieved by minimizing the number of vertices needed to represent a visibility function within a desired error tolerance.

The invention discloses a guide image filtering based adaptive infrared image detail enhancement method, which comprises the steps of firstly dividing an original image into a basic layer containing a low-frequency background and a detail layer containing high-frequency details by adopting a guide filter; then processing the basic layer by adopting an improved adaptive histogram projection algorithm so as to realize improvement for the image contrast and improve the scene adaptability of the algorithm; meanwhile, processing the detail layer by adopting a method based on a noise visibility function so as to enhance image details and suppress image noise; and finally building a final output image by using the processed basic layer and the processed detail layer. According to the invention, true infrared image data under multiple scenes can be effectively improved by adopting an adaptive threshold parameter selecting method and a simpler detail layer processing process, the output image is good in contrast and rich in detail and has good visual effects, and the real-time performance of the algorithm is also good.

A method and apparatus for rendering shadows. A pre-rendering process implements a two dimensional array or map of depth-based functions, such as a visibility function in z. During rendering of an object scene, these functions are accessed via lookup operations to efficiently determine the function value for a sample point at a given depth. The use of visibility functions allows for partial light attenuation effects. Each visibility function is computed by filtering multiple transmittance functions obtained by casting sample rays from a light source onto an object scene. The visibility function is implemented as a sequence of vertices. Colored shadows are modeled by vertices comprising a depth value and separate visibility function values for red, green, and blue light at a given depth value. Compression is achieved by minimizing the number of vertices needed to represent a visibility function within a desired error tolerance.

The present invention relates to adaptive 3D scanning wherein a scan sequence for obtaining full geometrical coverage of a physical object are created automatically and specifically for the physical object, by using a method and a system for producing a 3D computer model of a physical object, wherein the method comprises the following steps providing a scanner system, said scanner system comprising a scanner, and a computer connectable to and / or integrated in said scanner, said computer comprising a virtual model of said scanner, entering shape information of the physical object into the computer, creating in said computer a visibility function based on said virtual model and the shape information, said visibility function being capable of evaluating the coverage of areas of interest of the physical object by at least one predetermined scan sequence, establishing at least one scan sequence based on the evaluation of the visibility function, performing a scan of the physical object using said at least one scan sequence, and obtaining a 3D computer model of the physical object.

The invention discloses a blocking effect analysis method. The method comprises the following steps: inputting a decoded image; calculating brightness differences on boundaries among pixel blocks; utilizing a blocking effect visibility function to process the brightness differences on the boundaries among the pixel blocks; utilizing a Weber-Fick inner law to calculate the subjective sensation of a human vision system to visible blocking effects; and integrating the blocking effects on all the boundaries in the image to obtain the blocking effect evaluation analysis results of the whole image. The blocking effect analysis method and the system can accurately realize the blocking effect evaluation so that results can more suit the subjective sensation of the eyes.

The invention discloses an image inversion method of a non-uniform sampling comprehensive bore diameter radiometer. The image inversion method comprises the steps that the positions of non-uniform sampling points are calculated according to position coordinates of antenna units, and the values of the visibility functions of the non-uniform sampling points are obtained; according to the positions of the non-uniform sampling points, a spatial frequency domain is divided into a plurality of regions, and the area of each region is calculated; according to the area of each region, discrete convolution operation is conducted on the values of the visibility functions of the non-uniform sampling points, and the values of the visibility functions of uniform sampling points are obtained; inverse Fourier transformation is conducted on the values of the visibility functions of the uniform sampling points, and a middle brightness temperature distribution image of an observation space is obtained; according to the middle brightness temperature distribution image and the result of inverse Fourier transformation of a window function, a correction scene brightness temperature image is obtained; according to the correction scene brightness temperature image and the reciprocal of an inclination factor of the observation scene brightness temperature, an observation scene brightness temperature image is obtained. The image inversion method can rapidly, efficiently and accurately achieve inversion of a scene brightness temperature distribution image of the non-uniform sampling comprehensive bore diameter radiometer.

Provided is a system, a method, and a computer readable medium for inverse graphics rendering. The system comprises a differentiable rendering pipeline and a gradient descent optimization engine. A given scene is described using scene parameters. Visibility functions, and other rendered functions, are constructed to be continuous and differentiable, allowing the optimization engine and the rendering pipeline to efficiently iterate through increasingly refined scene models.

The invention discloses a three-dimensional antenna array synthetic aperture radiometer segmented image inversion method. The method includes diving an observation view field interval into N subintervals; putting an external correction source in each of the divided N view field intervals; sequentially measuring visibility functions of the external correction sources output by the three-dimensional antenna array synthetic aperture radiometer in the N view field subintervals, and obtaining phase angles of the visibility functions; performing simulation calculation on the phase of the visibility function under the condition that the three-dimensional antenna array synthetic aperture radiometer only has two-dimensional coordinates; sequentially subtracting the phase angle obtained by simulation from the phase angles measured in the N view field subintervals to obtain phase compensation angle of the nth view field subinterval; using the three-dimensional antenna array synthetic aperture radiometer to observe a target scene, and sequentially performing image inversion on the divided N view field subintervals; and splicing inversion images in the N view field subintervals into an inversion image in the whole view field. The method is relatively high in precision, and has relatively good application prospects.

Programmable or user-defined visibility functions can be defined to achieve rendering effects and eliminate rendering errors. A renderer traverses the set of geometry samples potentially visible to an image sample. Rather than accumulate opacity and color in strict depth order, the renderer can invoke visibility functions associated with some or all of the geometry samples. Each geometry sample's visibility function can access attributes of any other geometry sample associated with the image sample. Furthermore, each geometry sample's visibility function can identify the position of its associated geometry sample and any other geometry samples in the depth sequence of geometry samples associated with an image sample. A visibility function can return any arbitrary value based on attributes of its associated geometry sample, attributes of other geometry samples associated with the image sample, and / or the position of geometry samples in the depth sequence associated with the image sample.

The invention discloses a multiscale fusion-based synthetic aperture imaging method. The method comprises the steps of carrying out multiscale detection on a target scene under the premise of not changing the system structure, so as to obtain visibility function sampling values under different scales; combining the obtained multiscale visibility function values into a fused visibility function set, and constructing a multiscale sensing matrix model matched with the fused visibility function set; and carrying out rapid solution on the multiscale sensing model through an FGP method, so as to reconstruct a high-precision millimeter wave image. According to the method, a super-resolution fusion thought is used for reference; and a proposed MsF method is higher in reconstruction precision whenbeing compared with the traditional image fusion method which firstly carries out inversion and then carries out fusion, and is capable of effectively improving the imaging detection precision of thesynthetic aperture radiometers.

The invention provides a new multiband passive synthetic aperture imaging system. Spatial frequency sampling coverage of the imaging system is greatly improved by a multiband technology, thereby realizing high-resolution and high-quality imaging in real time while working in a radio-frequency microwave band. In the invention, signals radiated and scattered by a target are received by a multiband antenna array, and enters an array receiver; the signals are mixed with local oscillation signals output by an ultra wideband tunable YIG (yttrium iron garnet) oscillator; the mixed output signals are filtered to acquire intermediate frequency signals; the intermediate frequency signals are output after intermediate frequency amplification; and finally, after passing through an analog-to-digital conversion acquisition card, the signals are input into a signal processor for carrying out pairwise correlation calculation to acquire spatial frequency sampling of a field of view. By tuning the YIG oscillator by using the multiband antenna array, visibility functions of different frequency bands can be acquired, thereby greatly improving the coverage effect of target spatial frequency sampling and the imaging quality.