1373 results about "Back projection" patented technology

A scanning method for scanning samples of biological cells using optical tomography includes preparing, acquiring, reconstructing and viewing three-dimensional images of cell samples. Concentration and enrichment of the cell sample follows. The cell sample is stained. Cells are isolated from the cell sample and purified. A cell/solvent mixture is injected into a gel by centrifugation. A cell/gel mixture is injected into a capillary tube until a cell appears centered in a field of view using a step flow method. An optical imaging system, such as a fixed or variable motion optical tomography system acquires a projection image. The sample is rotated about a tube axis to generate additional projections. Once image acquisition is completed, the acquired shawdowgrams or image projections are corrected for errors. A computer or other equivalent processor is used to compute filtered backprojection information for 3D reconstruction.

An image input unit inputs a plurality of images in a time series. Each input image includes a boundary line extending toward a vanishing point on a plane. A reverse projection image generation unit generates a reverse projection image of each input image by projecting information related to each input image onto the plane. A boundary line detection unit detects the boundary line from the reverse projection image by identifying a boundary line candidate on each reverse projection 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 comers 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 invention relates to a three-dimensional wire frame structure method and system fusing a binocular camera and IMU positioning. On the basis of binocular vision, the invention initializes and fusesinertial measurement information by using a divide-and-conquer strategy, implements tracking, positioning and drawing, and can robustly run in indoor and outdoor environments and complex motion conditions. On the basis of accurate positioning, 3D wireframe reconstruction and iterative optimization are carried out based on the posture of the key frame. Linear segments are matched by local featuresand spatial geometric constraints and back-projected into three-dimensional space. Through the angle and distance constraints, the straight line segments are divided into different sets. Based on thegrouping results, the fitting region is determined and the straight line segments are merged. Finally, a 3-D wireframe structure is output. The invention fuses multi-source information to improve thestability and robustness of the system on the traditional vision-based positioning and mapping method. At the same time, line information is added to the key frame to sparsely express the structuralcharacteristics of the three-dimensional environment, which improves the computational efficiency.

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.

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 display system is provided to surround a user with an out-the window scene. The system includes a screen structure that is a facetted back-projection dome made up of a polygonal polar top facet surrounded by trapezoidal facets angulated downward from it in an upper facet row. A middle row of facets extends angulated downward therefrom, and a lower row of trapezoidal facets extends down from them. Each facet has video projected thereon by a high definition projector, and to maximize resolution and efficiently use the projector output, the vertical height of each facet makes use of the full vertical field of pixels available from the associated projector. The facets are all tangent to a sphere about a design eyepoint of the dome. The projector resolutions and the size, position and material of the facets are such that the imagery visible on the inside of the dome on the facets is at resolution corresponding to a visual acuity of 20/50 or higher, preferably 20/20, and at or near eye-limiting resolution.

A projectile tracking system for acquiring and precisely tracking a projectile in flight in order to reveal the source from which the projectile was fired. The source is revealed by the back projection of a 3-dimensional track file. In preferred embodiments the system is installed on a vehicle, such as an un-manned blimp or other aircraft, road vehicle or ship, for locating and destroying small arms fire directed at the vehicle. A kill system may also be included on the vehicle to destroy the source of the projectile.

An improved method and a system are disclosed for recovering a three-dimensional (3D) scene structure from a plurality of two-dimensional (2D) image frames obtained from imaging means. Sets of 2D features are extracted from the image frames, and sets corresponding to successive image frames are matched, such that at least one pair of matched 2D features refers to a same 3D point in a 3D scene captured in 2D in the image frames. A 3D ray is generated by back-projection from each 2D feature, and the generated 3D rays are subjected to an anchor-based minimization process, for determining camera motion parameters and 3D scene points coordinates, thereby recovering a structure of the 3D scene.

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.

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 reprojection/backprojection technique and apparatus for carrying out such a technique provides a hierarchical solution to speeding-up reprojection and backprojection of tomographic images. In the context of reprojection, a tomographic image is divided into a series of subimages. Each subimage is shifted to the origin, projected at a reduced number of views, and then up-sampled and shifted back (in the sinogram space). The resulting sinograms are then combined to provide a single sinogram. This process is applied one or more times recursively. In the context of backprojection, the above steps are transposed such that a sinogram is divided into a series of subsinograms. The subsinograms are then shifted and decimated by a given decimation factor. The decimated subsinograms are then backprojected onto hexagonal tiles whereupon the tiles are composited into a final image.

The invention relates to a visual inertial navigation SLAM method based on ground plane hypothesis. According to the method, feature points are extracted from an image to perform IMU pre-integration,a camera projection model is established, and camera internal parameter calibration and external parameter calibration between an IMU and a camera are performed; a system is initialized, a visually observed point cloud and a camera pose are aligned to the IMU pre-integration, and a ground equation and the camera pose are restored; the ground is initialized to obtain a ground equation, the ground equation under the current camera pose is determined and back projected to an image coordinate system, and a more accurate ground region is acquired; and based on state estimation, all sensor observation models are derived, camera observation, IMU observation and ground feature observation are fused to do state estimation, a graph optimization model is used to do state estimation, and a sparse graph optimization and gradient descent method is used to realize overall optimization. Compared with previous algorithms, the precision of the method is greatly improved, estimation of the camera pose can be limited globally, and therefore accuracy is greatly improved.

A method for iteratively reconstructing image data acquired by a computed tomography system is provided. The method comprises generating a calculated sinogram from an image estimate and generating an error sinogram based on the calculated sinogram and a measured sinogram. Then, one or more backprojections are performed, each based upon a reconstruction parameter. The reconstruction parameter impacts at least one of convergence speed and computational cost of each iterative step and corresponding reconstruction. A filtering step is performed prior to performing the one or more backprojections. Finally, the initial image is updated by adding corresponding results of the one or more backprojections to the image estimate to obtain the reconstructed image.

The invention discloses a small animal living body multi-mode molecule imaging system and an imaging method. The imaging system comprises a Cerenkov luminous imaging device, a nuclide imaging device and a MicroCT (micro computed tomography) device which respectively acquire Cerenkov optical signals, nuclide signals and X-ray signals of body surfaces of small animals. The X-ray signals are reconstructed by the aid of cone-beam back-projection algorithm, and information of an anatomical structure of a small animal is obtained; the Cerenkov optical signals are reconstructed on the basis of a mixed light transmission theory, and three-dimensional distribution information of a Cerenkov target is obtained; and the obtained Cerenkov target information and the obtained anatomical structure information are fused and displayed, so that multi-mode imaging is completed. A single-mark probe/multi-mode imaging mode which integrates high specificity of nuclide imaging, high sensitivity of optical imaging and high resolution of X-ray imaging is realized, so that multi-mode image information of small animal living bodies is more complete, comprehensive and accurate.