Shear mapping

Abstract: The invention discloses a method for converting a virtual 3D (Three-Dimensional) scene into a 3D view. The method can be used for converting any virtual 3D scene in OpenGL into a three-dimensional view by the following steps of: rotating and translating a world coordinate system, wherein an observation point is taken as the original point of a new coordinate system, and a connecting line between the central position of viewpoints and the observation point serves as an axis-Z positive axis; determining a rotating angle and a translating distance according to the central position of the viewpoints and the coordinate of the observation point; determining the shear mapping angle of each viewpoint according to the central position of the viewpoints and the coordinate of each viewpoint to generate a corresponding shear mapping matrix, performing right-handed multiplication on a model view matrix of each viewpoint, and projecting to obtain corresponding image data of each viewpoint; and adjusting the coordinate of the 3D scene, the horizontal resolution of the view, the size of a view frustum and the positions of the viewpoints according to a constraint condition of a parallax error and 3D effect experience to improve the 3D effect of the 3D view. Shear transformation and parameter adjustment are inserted in an OpenGL processing flow, so that the problems of unremarkable 3D effect and the presence of vertical parallax are solved, and an optimal 3D effect is achieved.

Abstract: The invention discloses a shear mapping deformable body drawing method based on anisotropic body data, belonging to the technical field of image processing and comprising the following steps of constructing a three-dimensional data field, shear mapping, deforming and decomposing, resampling, synthesizing an intermediate image, deforming to obtain the final image, and the like. The invention is mainly improved on the steps of coordinate transformation, resampling, opacity correction and the like of an original shear mapping and deforming algorithm, can realize isotropy without cross-section interpolation operation after image data are constructed into a logic three-dimensional data field, and can directly implement body drawing operation based on an anisotropic data field, thereby not only reducing the preprocessing time, but also improving the data precision of images for drawing. In addition, a variable resampling mode is adopted in the implementation process, the sampling rate is reduced and the drawing speed is improved during mouse interaction, the sampling rate is increased and the image quality is improved when a final image is drawn, and meanwhile, the requirements for drawing speed and image precision are met.

Abstract: The invention belongs to the field of sonar imaging, and provides portable three-dimensional imaging sonar and an imaging method and system thereof. According to the method and system, a shear mapping-deformation technology is applied to the imaging process of the portable three-dimensional imaging sonar. The method comprises the steps that first, an object space is projected into a shear mapping space through shear mapping transformation, an intermediate image is synthetized, the observation direction of the intermediate image is parallel to the Z-axis direction, then the intermediate image is deformed to a preset image space, and a final three-dimensional result image is obtained. By the aid of the intermediate image perpendicular to the Z-axis direction, the re-sampling process of three-dimensional space is converted to be the sampling process of a two-dimensional plane, calculation is greatly reduced, the requirement of the system for hardware performance is lowered, the real-time performance of display can be improved, and the imaging method and system are particularly suitable for the portable three-dimensional imaging sonar.

Abstract: A computer program, computer-implemented system and method generate a two-dimensional image of a volume data set representing an object volume from a selectable viewpoint. An object volume data set includes voxel values ordered by voxels along a row that extends in a first direction, rows across a plane that extends in the first direction and a second direction, and planes through an object volume that extend in the first and second directions and a third direction (see figures 5 and 6). In response to the definition of a view vector (VV, figures 11A and 11B) defining a view direction with respect to a viewpoint, shear and warp mappings are determined, as is which of the first, second and third directions (i, j, k, figures 11A and 11B) is closest to the view vector. Pixels of a two-dimensional sheared image having a plurality of lines of pixels are then determined from voxel values of the object volume data set identified by the shear mapping 92. Where the view vector is closest to the first direction, the shear mapping 92 maps rows of voxels in the first direction onto lines of pixels of the sheared image. An output image is then determined by mapping pixels of the sheared image according to the warp mapping 96. This output image can be displayed, printed, sent to a remote location or otherwise communicated to a user.