1383 results about "Back projection" patented technology

To enable an artifact free reconstruction even in the case of large regions of interest and with scanning paths of below 360°, provision is made for a method, with which a three-dimensional image volume is reconstructed from a number of two-dimensional projection images of a region of interest, which were recorded about the region of interest during a rotation of a recording system, comprising an x-ray source with a focal point and a detector, by calculating the gray scale values of the voxels of the image volume by back projection of the projection images, with which each two-dimensional projection images is composed in each instance from at least two individual projection images to form an extended two-dimensional projection image, with the respectively at least two individual projection images being recorded with a constant relative position between the focal point and the region of interest.

A photoacoustic imaging apparatus is provided for medical or other imaging applications and also a method for calibrating this apparatus. The apparatus employs a sparse array of transducer elements and a reconstruction algorithm. Spatial calibration maps of the sparse array are used to optimize the reconstruction algorithm. The apparatus includes a laser producing a pulsed laser beam to illuminate a subject for imaging and generate photoacoustic waves. The transducers are fixedly mounted on a holder so as to form the sparse array. A photoacoustic (PA) waves are received by each transducer. The resultant analog signals from each transducer are amplified, filtered, and converted to digital signals in parallel by a data acquisition system which is operatively connected to a computer. The computer receives the digital signals and processes the digital signals by the algorithm based on iterative forward projection and back-projection in order to provide the image.

Various embodiments involving structures and methods for illumination can be employed, for example, in projectors, head-mounted displays, helmet-mounted displays, back projection TVs, flat panel displays as well as other optical systems. Certain embodiments may include prism elements for illuminating, for example, a spatial light modulator. Light may be coupled to the prism in some cases using fiber optics or lightpipes. The optical system may also include a diffuser having scatter features arranged to scatter light appropriately to produce a desired luminance profile. Other embodiments are possible as well.

A moving object detected and tracked within a field of view environment of a 2D data feed of a calibrated video camera is represented by a 3D model through localizing a centroid of the object and determining an intersection with a ground-plane within the field of view environment. An appropriate 3D mesh-based volumetric model for the object is initialized by using a back-projection of a corresponding 2D image as a function of the centroid and the determined ground-plane intersection. Nonlinear dynamics of a tracked motion path of the object are represented as a collection of different local linear models. A texture of the object is projected onto the 3D model, and 2D tracks of the object are upgraded to 3D motion to drive the 3D model by learning a weighted combination of the different local linear models that minimizes an image re-projection error of model movement.

An iterative image reconstruction method used with an imaging system that generates projection data, the method comprises: collecting the projection data; choosing a polar or cylindrical image definition comprising a polar or cylindrical grid representation and a number of basis functions positioned according to the polar or cylindrical grid so that the number of basis functions at different radius positions of the polar or cylindrical image grid is a factor of a number of in-plane symmetries between lines of response along which the projection data are measured by the imaging system; obtaining a system probability matrix that relates each of the projection data to each basis function of the polar or cylindrical image definition; restructuring the system probability matrix into a block circulant matrix and converting the system probability matrix in the Fourier domain; storing the projection data into a measurement data vector; providing an initial polar or cylindrical image estimate; for each iteration; recalculating the polar or cylindrical image estimate according to an iterative solver based on forward and back projection operations with the system probability matrix in the Fourier domain; and converting the polar or cylindrical image estimate into a Cartesian image representation to thereby obtain a reconstructed image.

The invention provides improvements in reconstructive imaging of the type in which a volume is reconstructed from a series of measured projection images (or other two-dimensional representations) generated by projection of a point x-ray source (or other radiation source), positioned at a distinct focus, through the volume to a plane at which the respective projection image is acquired (“detector plane”). In one aspect, the improvements are with respect to back-projecting a two-dimensional representation lying in the detector plane (representing, for example, a difference between an originally-acquired measured projection image and a subsequently-generated estimate thereof) to generate three-dimensional representation (which can be used, for example, to update an estimate of the volume). According to this aspect, for each of one or more slices of the 3D representation parallel to the projection plane and for each distinct focus at which a projection is generated, the following steps are performed in connection with the back-projection: (i) warping the first 2D representation to generate a second 2D representation by applying to the first 2D representation a selected linear mapping, where that selected linear mapping would map, in order to match dimensions of the respective slice within the 3D representation, a region defined by projection, at the respective focus, of corners of that slice onto the detector plane, and (ii) incrementing values of each of one or more voxels of the respective slice by an amount that is a function of a value of a correspondingly indexed pixel of the second 2D representation. A related aspect provides improvements with respect to forward-projecting, as well as in iterative (and non-iterative) methodologies that incorporate both back-projection and forward-projection.

The present invention is a radar system for detecting the presence of obstacles. The radar system includes at least one transmitting antenna and at least one receiving antenna. The transmitting antenna receives an input signal and transmits an electromagnetic wave. The electromagnetic wave reflects off an obstacle back to the receiving antenna. The receiving antenna captures the reflected electromagnetic wave and produces an output signal. The output signal is then combined with the local reference signal in a quadrature mixer. The resulting in-phase (I) and quadrature (Q) signals may be further processed and then transmitted to a processing system. The processing system uses a suitable algorithm, e.g., a back projection algorithm, to estimate the type and location of obstacles that reflected the electromagnetic wave. In an exemplary embodiment, the algorithm is adapted to discriminate between different sizes and locations of obstacles in order to determine if there is a hazard. Based on this information, the processing system then communicates with a visual and / or audible warning system in order to alert the driver about the obstacle if it has been determined to be a hazard.

A method for processing an image captured by a fisheye lens of an image capture device. The method obtains a point (Px, Py) from an object plane of the fisheye lens, calculates a first projection point (Fx*, Fy*, Fz*) of the obtained point (Px, Py) on a first image plane of a virtual lens, calculates a second projection point (Fx, Fy) of the point (Fx*, Fy*, Fz*) on a second image plane of the fisheye lens, and obtains transforming formulae between (Px, Py) and (Fx, Fy). The method further obtains a back-projection point for each point of the captured image on the object plane of the fisheye lens according to the transforming formulae, and creates an updated image of the specified scene from the back-projection points.

Two-dimensional or three-dimensional, time-resolved CT frame images are acquired during a dynamic study of a subject. A composite image is produced and this is used to reconstruct each CT frame image by weighting the backprojection of each projection view acquired for that image frame by the corresponding value in the composite image. This weighted backprojection enables artifact-free image frames to be produced with far fewer projection views of the subject. The composite image may be reconstructed from views acquired separately, or it may be produced by combining views acquired during the course of the dynamic study.

A method of tracking a pose of a moving camera includes receiving a first image from a camera, receiving a sequence of digitized images from said camera, recording, for each of said sequence of digitized images, the pose and 2D correspondences of landmarks, reconstructing a location and appearance of a 2-dimensional texture patch from 2D correspondences of the landmarks by triangulation and optimization, computing back-projection errors by comparing said reconstructed texture patch with said first received image; and reconstructing said location and appearance of said 2-dimensional texture patch from the 2D correspondences of the landmarks of said sequence of digitized images by triangulation and optimization after eliminating those landmarks with large back-projection errors.

The invention relates to a universal flight simulator based on virtual operation, which comprises footstools, a throttle lever, a steering column and a sound blending box arranged in a universal concept cabin of the virtual operation; the universal concept cabin also comprises a sight display system consisting of a back projection system, a virtual switch, a knob and a virtual instrument operated by using a touch mode, a displaying and resolving center for model resolving, flight control resolving and acceleration resolving and a buffeting chair seated by a driver. The universal flight simulator based on virtual operation uses a virtual operation switch and the virtual instrument to replace a real physical hardware switch and an instrument and can flexibly switch the virtual switch, the instrument software and a flight control model into various models for flight training and games. The universal flight simulator is small in size, light in weight, convenient to disassemble and assemble and suitable for use under the ordinary office condition, has vivid simulation, low price and strong universality through switching models by software and can be combined to a simulator set with different models for confronting training and games after being connected to the Internet.

A method to generate super-resolution images using a sequence of low resolution images is disclosed. The method includes generating an estimated high resolution image, motion estimating between the estimated high resolution image and comparison images from the sequence of low resolution images, motion-compensated back projecting, and motion-free back projecting that results in a super resolved image. A corresponding system for generating super-resolution images includes a high resolution image estimation module, a motion estimating module, a motion-compensated back projection module, a motion-free back projection module, an input interface, and an output interface.

The invention provides a GAMMA curvature correction and color-temperature automatic regulating method for liquid crystal display and the system. The said system consists of a system host-machine, a detector, a color analyzer, a video standard signal source, a data interface,and a system measure and correction software, which can perform GAMMA curvature correction and white balance adjustment for multi-purpose TV and computer display including LCD and high-resolution back projection and multi-structure liquid crystal display including TN, STN, DSTN and TFT to improve the videograph display quality of the liquid crystal display. The system host-machine connects multiple video signal sources, automatic measurement and correction software for GAMMA curvature and color-temperature and data interface together, the system parameter can be set manually or automatically, the system configuration is simple, GAMMA curvature correction and white balance adjustment software can be conveniently transferred, and can rapidly finish automatic measurement and correction for GAMMA curvature and color-temperature and can visually inspect the effect. The invention can be used in departments including scientific research, production, quality inspection and maintenance and can visually finish the GAMMA curvature correction and white balance adjustment for the LCD products with high accuracy and quick-speed.

The invention discloses a ground obstacle detection method based on the binocular stereo vision of a robot, which belongs to the technical field of intelligent robots, and comprises the following steps that: according to the binocular baseline length and the focus, the ground parallax values of all rows in an image are analyzed through the geometrical configuration of the known image; based on the ground parallax values, a back projection model calculates the three-dimensional coordinates of a scene point corresponding to a pixel so as to initially judge whether the pixel belongs to an obstacle or a ground point; the obstacle and the ground point are respectively endowed with different colors; the results are post-processed and the false obstacle is removed; and three-dimensional errors are removed and a grid map is established. The method is applicable to various complicated indoor environments, can precisely identify various obstacles, has very high real-time performance, and provides very good preparation conditions for the robot to avoid obstacles.