41 results about "T-spline" patented technology

The present invention discloses a three-dimensional print slicing method based on a T-spline surface. The method comprises: inputting a to-be-processed T-spline surface, a slice layer thickness and a slice data allowable error; in a T-spline surface parameter field, generating a uniformly distributed parameter grid, and calculating a corresponding Euclidean space grid; according to a model layer thickness, selecting a grid point whose z coordinate is closest to a current layer as a slide initial point at each layer; iterating the slide initial point that exceeds the error along a steepest change direction; by using the slide initial point of each layer as a start point, tracking along an unchanged direction of the z coordinate of the surface, and iterating a slide point that exceeds the error along the steepest change direction, and finally obtaining all slice points that satisfy a precision requirement; and connecting the slice points of each layer, and outputting a slice contour. According to the method provided by the present invention, slicing of the T-spline surface is realized by using a numerical method, and the defects of huge data volume and low precision of traditional three-dimensional printing are solved, so that the method is particularly applicable for three-dimensional print slice processing of models with a complex free surface appearance or internal holes.

A system and method is provided for defining a bi-cubic spline surface in a computing environment. One operation in the method is creating a control mesh with a substantially rectangular structure. A further operation is inferring from the control mesh the tensor product B-spline basis functions for each control point. The surface can then be computed based on the basis functions and the control mesh.

The present invention discloses a B-spline-based incremental scaling and translation construction method of an interpolation curve or curved surface. The method includes the following steps that: a blending function is selected, a straight line connected with two end points of each spline subinterval and a straight line connected with two adjacent corresponding de Boor control vertexes are constructed, the differences of points on spline curves on spline subintervals and points on the straight line of the two end points of each spline subinterval are obtained, and so that incremental vectors are obtained; the incremental vectors are scaled, and then the scaled incremental vectors are translated onto the straight line connected with the two adjacent de Boor control vertexes, so that an interpolation curve about the interpolation of the spline subintervals into the de Boor control vertexes can be obtained, wherein the constructed curve about the interpolation of the spline subintervals into the de Boor control vertexes is a third-order B-spline curve. As for a four-order quartic B-spline curve, the incremental scaling and translation construction method can be also adopted to generate a corresponding interpolation curve. The method of the invention has the advantages of simplicity and obvious geometric significance, and is of great significance for geometric modeling.

The invention provides a numerical control processing method and a numerical control processing system for realizing T spline model based on OCC. The numerical control processing method comprises the steps of obtaining a T spline data file, generating a T spline model according to the T spline data file; receiving a processing parameter which is input by a user, and generating a processing tool path according to the processing parameter through an equal residual height tool path generating method; determining processing error and interference information of the processing tool rail according to the processing parameter through a cutting simulation algorithm; if the machining error is smaller than a preset value and no interference information exists, generating a processing code according to the processing parameter and the processing tool path; and performing numerical control processing on the T spline sample according to the processing code. Through constructing CAM software which supports T spline model processing and simulation based on OCC, functions such as modeling, displaying and data exchange in the OCC can be directly called, thereby supplying a processing simulation function, realizing processing error and interference condition analysis, supplying basis for determining whether the tool path is qualified, and improving efficiency of a numerical control processing solution for generating the T spline model.

The invention provides a precise grinding track generation method based on a B spline. The method comprises steps that a workpiece CAD model is established; based on the workpiece CAD model, a grinding area is analyzed, and key grinding work path points are acquired; B spline interpolation for the acquired grinding work path points is carried out; whether the interpolation result satisfies precision requirements is determined; speed programming is carried out for the interpolation result, when the interpolation result is consistent with the precision requirements, actual work demands and self restrictions of robots are considered, and speed programming is carried out; the spline track is outputted. Compared with work tracks through linear and arc-shaped fitting, the method is advantaged in that higher fitting precision is realized.

The present invention discloses a partition local fairing weight factor-based T-spline curved-surface fitting method. The method comprises the following steps of inputting a parameterized triangular grid and an initial T-spline; segmenting the region of a parameter domain to obtain a plurality of sub-regions of the parameter domain; according to the topological structure of the original image of the control grid of the input T-spline on the parameter domain, generating a fairness inspection point set; according to the density weight of each fairness inspection point and the local fairness weight factor of the sub-region of the above fairness inspection point, calculating the local fairness weight of each fairness inspection point; according to the fitting error of each vertex of the triangular grid and a curved-surface fairness energy column equation set, conducting the least square solution method to obtain a final T-spline curved-surface fitting result. According to the invention, fairness inspection points are adaptively generated according to the complexity of a control grid. Meanwhile, the fairness and the accuracy of different regions are coordinated through partition and local fairness weights. Therefore, the quality of a fitting surface is improved and the calculation efficiency is increased.

The invention discloses a geometric iteration image fitting method based on a T spline. An image M with a resolution ratio is given, a value (R, G and B) at each pixel point of the image serves as a data point, and a bi-cubic B spline curved surface is selected to serve as an initial curved surface to carry out fitting on the image M; geometric iteration is carried out on the initial curved surface according to an iteration equation, and a kth T spline curved surface T (k) (u, v) is generated; the following judgment is carried out after each iteration: an overall fitting error epsilon k is obtained according to an error vector between the current T spline curved surface T (k) (u, v) and the data point Iwh, the overall fitting error epsilon k is compared with an overall fitting error epsilon k-1 corresponding to a previous T spline curved surface T (k-1) (u, v), and when the difference value of the overall fitting error epsilon k and the overall fitting error epsilon k-1 tends to zero, the iteration is finished; if the iteration error does not meet the accuracy requirement, a node is inserted, a grid is regulated, and the geometric iteration proceeds; if the iteration error meets the accuracy requirement, a needed T spline fitting curved surface is generated, and the algorithm is finished.

The invention discloses a T-spline and isogeometric analysis-based die surface springback compensation method. The method comprises (1) a stress iteration die surface compensation method and (2) a displacement iteration die surface compensation method. The stress iteration die surface compensation method comprises the steps of 1, converting a trimmed NURBS model into T-splines; 2, splicing the T-splines; 3, performing Bezier extraction to obtain an adaptive analysis model; 4, performing forming simulation; 5, calculating deformation force; 6, performing springback simulation; 7, calculating a shape error, and if a condition is met, going to the step 9, otherwise, going to the step 8; 8, reversely applying the deformation force to the adaptive analysis model to perform simulation, and going to the step 4; and 9, modifying an initial T-spline model. The displacement iteration die surface compensation method comprises the steps of 1, converting the trimmed NURBS model into the T-splines; 2, splicing the T-splines; 3, performing the Bezier extraction to obtain the adaptive analysis model; 4, performing the forming simulation; 5, calculating the deformation force; 6, calculating a deviation of a control vertex; 7, calculating the shape error, and if the condition is met, going to the step 9, otherwise, going to the step 8; 8, reversely applying the deviation of the control vertex to the adaptive analysis model to perform simulation, and going to the step 4; and 9, modifying the initial T-spline model. According to the method, numerical simulation of a plate forming springback process and compensation of a simulation result are realized.

A first T-spline fitting system includes a three-dimensional (3D) sensor, a processor and a memory storing a program for representing a point cloud of the scene using T-spline representation. The system executes acquiring an image of the scene using the 3D sensor, generating the point cloud from the image, determining a parameterized domain of the point cloud by mapping data points of the point cloud to values of parameters of the parameterized domain, partitioning recursively the parameterized domain into a set of patches, connecting the patches to form a T-mesh defining topology of control points in the parameterized domain, and fitting a T-spline surface into the point cloud according to the T-mesh to determine positions of the control points.

The invention discloses a T spline surface-based porous sandwich structure. The structure is obtained through a method comprising the following steps of: inputting two T spline surfaces, an implicit porous structure function expression, a surface discrete grid resolution and an inter-surface interpolation grid resolution; carrying out isoperimetric segmentation on the two T spline surfaces according to the surface discrete grid resolution so as to obtain discrete grids; generating uniformly distributed interpolation grids between the two T spline surfaces according to the inter-surface interpolation grid resolution and the T spline surface discrete grids; carrying out linear interpolation according to the interpolation grids and the implicit porous structure function expression so as to generate a porous structure; and finally storing the generated porous sandwich structure into an STM format and outputting the STM-format porous sandwich structure. The invention furthermore discloses an application of the T spline surface-based porous sandwich structure as wing wall panel material.

The invention discloses a meteorological facsimile map isoline interpolation method based on T-spline. Firstly, the meteorological facsimile map is pretreated to obtain an image only containing the isoline. Then point-by-point screening method is used to sample the processed contours and extract the data points. T grid is established according to the data points; Finally, the T-spline local node interpolation algorithm is used to interpolate the image, and the interpolated points are fitted into curves to form the interpolated contours. The invention improves the operation speed and the ability of local interpolation, and reduces the accumulation of errors and data redundancy.

The invention discloses an improved TPS (thin plate spline) model based gel image correction algorithm. The algorithm includes: comparing a distorted image with a template image to acquire a deformation degree coefficient beta and a column number nclm of the distorted image, and introducing a height correction coefficient to obtain a 'smile' deformation model; acquiring n pairs of corresponding distorted image mark point coordinates ipts and template image mark point coordinates opts in the distorted image and the template image, and utilizing the 'smile' deformation model to transform the coordinates ipts to obtain mark point coordinates Sipts; utilizing the mark point coordinates Sipts and the template image mark point coordinates opts to obtain unknown parameters wi (i=1...n), a0, ax and ay of the TPS deformation model; creating an image wimg which is equal to the distorted image in size and zero in gray value, and performing 'smile' deformation and TPS deformation on the coordinates; assigning the gray value of the template image to the image wimg with the gray value being zero according to the corresponding relation between the distorted image coordinates and the template image coordinates; considering the assigned image wimg as the corrected image. Compared with the original correction algorithm, the improved TPS model based gel image correction algorithm has the advantages that better correction effect is obtained, and good preconditions are provided for matching of gel images.

The invention relates to a quick image registration method based on B spline and Levenberg Marquardt optimization. An image registration problem is converted into a target function minimum solving problem herein; a triple B spline is sued to simulate nonrigid deformation of an image; Levenberg Marquardt optimization is used to perform iterative solving on the problem; based on the Levenberg Marquardt optimization, a Jacobian matrix with highest computing quantity is reused, an approximate iterative step is introduced, and optimal weight of the approximate iterative step is found by means of linear search. In order to eliminate the influence of a regularization item coefficient in the iteration process upon converging speed, the invention also introduces an adaptive method to determine thecoefficient; by establishing a correlation between variations of the coefficient and those of a target function value, it is possible to effectively accelerate algorithm convergence.

The invention provides a half-edge data structure-based T-mesh local refinement realizing method, which comprises the following steps: 1, establishing half-edge data structure-based T-mesh of the current T-splines; 2, determining all the surface patches, which need to be subjected to local refinement, in the current T-mesh; 3, increasing new edge points in the surface patches which need local refinement, and marking points related to segmentation of the surface patches; 4, determining peaks which the segmented surface patches and the non-segmented surface patches contain; and 5, reestablishing the half-edge data structure-based T-mesh which is subjected to local refinement. The half-edge data structure-based T-mesh local refinement realizing method realizes self-adaptive local refinement of the T-mesh of the T-splines, is absolutely necessary in actual application of triangular mesh curved surface fitting, T-splines based isogeometric analysis and the like, and is conducive to pushing further application of the T-splines in the fields of computer aided design, computer aided analysis and the like.

The invention relates to a real-time prediction method for aerodynamic performance parameters of an automobile based on three-dimensional deep learning. The method comprises the following steps: constructing a three-dimensional model of an automobile body by using a T spline; simulating and calculating aerodynamic performance parameters of the model by using CFD software, and adding a wind speed label into three-dimensional point cloud data so as to construct a training data set; and carrying out adaptive modification based on a PointNet network, taking the processed point cloud data as the input of a deep neural network, adjusting training parameters, and carrying out prediction on the aerodynamic performance parameters of the automobile by using the trained deep neural network. According to the method, rapid real-time prediction of the aerodynamic performance parameters of the automobile is achieved, tedious CFD calculation is avoided through direct application of experimental data, and the method has great significance in promoting application of deep learning in aerodynamics.

The invention particularly relates to a single-view three-dimensional flame reconstruction method based on deep learning and a thin plate spline, which solves the problems that in the existing three-dimensional flame reconstruction process, multi-view images are needed to complete estimation and calculation of object depth information, the manpower and financial cost is high, and the like. The method comprises the following steps: firstly, searching and retrieving a three-dimensional flame model most similar to input flame in an existing data set through a deep learning method; Then, comparingwith the multi-angle projection view of the three-dimensional flame model to obtain an optimal projection view; And finally, processing the three-dimensional flame model by using a three-dimensionalthin plate spline deformation method to realize the reconstruction of the three-dimensional flame model. The method is suitable for three-dimensional reconstruction based on a single flame image or asingle-view flame image. The method is a relatively stable and relatively accurate three-dimensional model retrieval method; Compared with the mode that a control box is constructed on the basis of the outline to drive deformation, the time complexity is lower when the same control point is selected.

The invention provides a T-spline-based aircraft skin seamless forming method, which comprises the following steps that a T-spline-based aircraft body structure is constructed according to the size requirement of aircraft skin, and stretching operation is performed on grids at empennage and flank positions of the aircraft body structure on the basis of the aircraft body structure to form a T-spline-based aircraft skin structure; t spline control points are additionally arranged at the joints of the fuselage and the empennages and the joints of the fuselage and the side wings, so that a complete aircraft skin is constructed through one T spline curved surface, a traditional NURBS curved surface aircraft skin forming mode is replaced by introducing the T spline curved surface, the topological level can be coordinated with the aircraft structure design requirement, and the aircraft skin forming efficiency is improved. And the data volume of the aircraft skin model is greatly reduced, and a large number of control points which do not carry geometrical information are deleted, and thus the local fairness of the skin surface is effectively improved; the problems of incoordination of a topological structure and an aircraft structure design requirement, redundancy of the model data volume and poor fairness of the skin surface existing in the aircraft skin forming method of the NURBS curved surface are solved.

The invention discloses a compression method suitable for a three-dimensional grid sequence, is suitable for compressing the three-dimensional grid sequence and improves the compression efficiency of the isomeric three-dimensional grid sequence, wherein each frame of the three-dimensional grid sequence has different topologic connection relationships. The method comprises the following steps: (1) utilizing a thin-plate spline (TPS) to carry out non-rigid registration on a geometry image sequence, wherein the geometry image sequence is generated in a way that a known three-dimensional grid sequence is subjected to parameterization and resampling; and (2) using an image compression algorithm JPEG (Joint Photographic Experts Group) 2000 to compress a residual error between every two frames of the geometry image sequence registered in the step (1).

The invention discloses a heterogeneous material entity modeling method based on a three-dimensional T spline, and the method comprises the steps: inputting a heterogeneous material tetrahedral grid,taking geometric coordinates and material information at the vertex of each grid as data points, and carrying out the parameterization of the data points to a given cube parameter domain; expressing the heterogeneous material entity as a geometric three-dimensional T spline and a material three-dimensional T spline, and initializing an initial three-dimensional T grid; according to the current geometric three-dimensional T spline or the material three-dimensional T spline, defining two corresponding energy functions to calculate an error between the current three-dimensional T spline and the tetrahedral mesh data point; secondly, dynamically optimizing corresponding control points by minimizing an energy functional until the difference value of two optimization results tends to zero, at the moment, if the fitting error does not meet the precision requirement, adjusting a three-dimensional T grid by inserting nodes through self-adaptive grid division based on an octree structure, and continuing the step of iteratively optimizing the control points; and if the fitting error meets the precision requirement, generating a required three-dimensional T spline fitting result.

The embodiment of the invention provides a machining track real-time planning method and device based on non-uniform B-splines, and belongs to the field of industrial automation. The method includes the steps that multiple offset point data input by a user are obtained; the multiple offset point data are divided into a plurality of to-be-planned units, and each to-be-planned unit includes at leastfour offset point data; a B-spline track unit corresponding to each to-be-planned unit is constructed; and every two adjacent B-spline track units are fused to generate a target B-spline track. Compared with methods in the prior art, by adopting piecewise spline track planning, the solution of large linear equation sets is avoided, the amount of calculation is reduced, the target B-spline trackscan be delivered to the subsequent interpolation process in time after being obtained, the problem of 'data starvation' in the interpolation process is solved, and the interpolation stability is improved.

The invention relates to a lip line completion method and device based on a B spline, electronic equipment and a storage medium, and belongs to the technical field of computers. The method comprises the steps that edge detection is conducted on a lip area image of a target object, and pixel points corresponding to lip lines are obtained; feature point detection is carried out on the lip region image to obtain feature points of the corresponding lip line; b spline curve fitting is conducted on the pixel points and the feature points, and a function relation model is established; sampling is carried out according to the function relation model, and the positions of sampling points are determined; and the sampling points are connected to obtain a complemented lip line. A traditional image processing method is replaced by the method, the lip lines which are continuous, smooth, single in pixel and accord with human lip characteristics can be obtained through the method, the mouth lip lines close to the real lip shape can be obtained without combining other image processing methods to carry out edge processing on the lip lines, and application based on the lip shape is facilitated.

The invention discloses a propeller blade adaptive measuring point planning method based on a T spline. The method comprises the following steps: (1) reading a propeller blade three-dimensional CAD model to extract a vertex set; (2) analyzing geometric topological information according to the vertex set to adaptively generate density factors; (3) establishing a density descriptor based on a K-Dtree search algorithm according to the vertex set; (4) integrating the density factor, the density description and other constraint segmentation regions, and generating a T spline representation original image; (5) generating a block basic measuring point set according to a self-adaptive sampling criterion according to the local domain; (6) constructing a T curve for the block basic measuring points, performing registration approximation with the initial characterization curve, and performing iterative interpolation to adaptively generate a result measuring point set; and (7) generating an intelligent planning path for the obtained result measuring point set according to a path optimization principle. The invention has good self-adaptability, can adapt to different models of propeller blades, is reasonable in measurement point arrangement and high in position coordinate precision, and realizes high-precision detection of the propeller blades.