基于物体坐标系的三维图形数据表示

鉴于世界坐标系定义的空间往往远大于被描绘物体的几何尺寸。导至了数据冗余、分辩率低、本文提出用物体坐标系表示三维图形，使存储空间减少，分辨率提高，并可提高运算速度。     

点阵测头成像视觉坐标测量系统的研究

柔性三维坐标测量在工业现场测量有较多应用.分析多目标点透视成像原理的基础上,提出了点阵测头成像视觉坐标测量的概念,给出系统完整的三种数学模型及求解方法.设计了一种实用测头,基于单台面阵CCD摄像机实现由三种类型测头组成的视觉测量样机.在距离摄像机1 000 mm,样机进行实际测量,并与三坐标测量机的检测结果进行比对.测试结果表明在摄像机成像面平行的两个方向的测量精度高于摄像机轴向测量精度.     

Low-cost microprocessor-based image processing system

The architecture, implementation and image processing facilities of the LS10 low-cost microprocessor-based image processing system are described. The paper presents a summary of the system's attributes, and emphasis is given to their use in practical image processing applications. Results for processed Landsat satellite images are presented and described to illustrate the performance achievable from the system. To perform complex computations rapidly, fast Fourier transforms for example, a transputer-based processor has been developed. The paper shows how this sytem can be interfaced to the image processor.     

Adaptive privacy-preserving visualization using parallel coordinates

Current information visualization techniques assume unrestricted access to data. However, privacy protection is a key issue for a lot of real-world data analyses. Corporate data, medical records, etc. are rich in analytical value but cannot be shared without first going through a transformation step where explicit identifiers are removed and the data is sanitized. Researchers in the field of data mining have proposed different techniques over the years for privacy-preserving data publishing and subsequent mining techniques on such sanitized data. A well-known drawback in these methods is that for even a small guarantee of privacy, the utility of the datasets is greatly reduced. In this paper, we propose an adaptive technique for privacy preservation in parallel coordinates. Based on knowledge about the sensitivity of the data, we compute a clustered representation on the fly, which allows the user to explore the data without breaching privacy. Through the use of screen-space privacy metrics, the technique adapts to the user's screen parameters and interaction. We demonstrate our method in a case study and discuss potential attack scenarios.     

Polygonal mesh watermarking using Laplacian coordinates

We propose a watermarking algorithm for polygonal meshes based on the modification of the Laplacian coordinates. More specifically, we first compute the Laplacian coordinates (x,y,z) of the mesh vertices, then construct the histogram of the lengths of the (x,y,z) vectors, and finally, insert the watermark by altering the shape of that histogram. The watermark extraction is carried out blindly, with no reference to the host model. The proposed method is more robust than several existing high capacity watermarking algorithms. In particular, it is able to resist attacks such as translations, rotations, uniform scaling and vertex reordering, due to the invariance of the histogram of the Laplacian vector lengths under such transformations. Compared to the existing robust watermarking methods, our experiments show that the proposed method can better resist common mesh editing attacks, due to the good behaviour of the Laplacian coordinates under such operations.     

Cage-free local deformations using green coordinates

Green coordinates require to build an enclosing cage around a shape that is deformed by manipulating the cage. In this paper, we build upon the local differences of Green coordinates and propose a method to deform a shape locally without constructing a cage. Second, we derive linear formulas to directly interpolate points on the shape to desired locations using an umbrella shaped cell. Moreover, we set up an influence region to confine the deformation in a local area. Finally, we suggest a method to automatically construct an umbrella shaped cell and thus update it consecutively while the shape is deforming. Experiments have shown that the suggested approach delivers smooth local deformations and enables shape manipulations at an interactive rate.     

Robust mesh editing using Laplacian coordinates

Shape deformation and editing are important for animation and game design. Laplacian surface based methods have been widely investigated and used in many works. In this paper we propose a robust mesh editing framework which improves traditional Laplacian surface editing. It consists of two procedures: skeleton based as-rigid-as-possible (ARAP) shape modeling and detail-preserving mesh optimization. Traditional ARAP shape modeling relies on the mesh quality. Degenerated mesh may adversely affect the deformation performance. A preprocessing step of mesh optimization can alleviate this problem. However, skinny triangles can still be generated during deformation, which adversely affect the editing performance. Thus our method performs Laplacian mesh deformation and optimization alternately in each iteration, which ensures mesh quality without noticeably increasing computational complexity or changing the shape details. This approach is more robust than those solely using Laplacian mesh deformation. An additional benefit is that the skeleton-based ARAP modeling can approximately preserve the volume of an object with large-scale deformations. The volume is roughly kept by leveraging the skeleton information and employing a carefully designed energy function to preserve the edge length. This method does not break the manifoldness of traditional ARAP methods or sacrifice speed. In our experiments, we show that (1) our method is robust even for degenerated meshes, (2) the deformation is natural in terms of recovering rotations, and (3) volumes are roughly kept even under large-scale deformations. The system achieves real time performance for surface meshes with 7k vertices.     

Low-cost model selection for SVMs using local features

Many practical engineering applications require the usage of accurate automatic decision systems, usually operating under tight computational constraints. Support Vector Machines (SVMs) endowed with a Radial Basis Function (RBF) as kernel are broadly accepted as the current state of the art for decision problems, but require cross-validation to select the free parameters, which is computationally costly. In this work we investigate low-cost methods to select the spread parameter in SVMs with an RBF kernel. Our proposal relies on the use of simple local methods that gather information about the local structure of each dataset. Empirical results in UCI datasets show that the proposed methods can be used as a fast alternative to the standard cross-validation procedure, with the additional advantage of avoiding the (often heuristic) task of a priori fixing the values of the spread parameter to be explored.     

Fuel consumption prediction for pre-departure flights using attention-based multi-modal fusion

Improper fuel loading decision results in carrying excessive dead weight during flight operation, which will burden the airline operation cost and cause extra waste emission. Existing works mainly focused on the post-event fuel consumption based on flight trajectory. In this work, a novel deep learning model, called FCPNet, is proposed to achieve the fuel consumption prediction (FCP) before the flight departure. Considering the influential factors for aircraft performance, the multi-modal information sources, including the planned route, weather information, and operation details, are selected as the model input to predict fuel consumption. Correspondingly, three modules are innovatively proposed to learn embedding features from multi-modal inputs. Based on the planned route, the graph convolutional network is proposed to mine the spatial correlations in the non-Eulerian route network. Considering the grid attributes of the weather information, the ConvLSTM is applied to learn abstract representations from both the temporal and spatial dimensions, in which the three-dimensional convolution neural networks are also designed to fine-tune intermediate feature maps. The fully connected layer is also proposed to learn informative features from operation details. Finally, an attention-based fusion network is presented to generate the final embedding by considering the unique contributions of the multi-modality sources, which are further applied to predict flight fuel consumption. A binary encoding representation is proposed to formulate the FCP task as a multi-binary classification problem. The proposed model is validated on a real-world dataset, and the results demonstrate that it outperforms other baselines, i.e., achieving a 6.50% mean absolute percentage error, which can practically support the airline operation and global emission control before flight departure.     

卫星制导弹药低成本飞控计算机系统设计

为满足某型卫星制导弹药飞控计算机系统的特殊要求,设计了一种基于浮点数字信号处理器TMS320C6713B FPGA的嵌入式导航计算机系统.系统通过采用大规模可编程器件FPGA,充分利用FPGA资源,进行合理的功能分配,不仅简化了硬件系统的设计,而且使得系统的功能设计更灵活;在此基础上,通过采用DSP/BIOS多任务多线程实时操作系统,进一步提高了系统软件的实时性和降低了软件编制的复杂性.     

Modeling smooth shape using subdivision on differential coordinates

Traditional subdivision schemes are applied on Euclidean coordinates (the spatial geometry of the control mesh). Although the subdivision limit surfaces are almost everywhere C² continuous, their mean-curvature normals are only C⁰. In order to generate higher quality surfaces with better-distributed mean-curvature normals, we propose a novel framework to apply subdivision for shape modeling, which combines subdivision with differential shape processing. Our framework contains two parts: subdivision on differential coordinates (a kind of differential geometry of the control mesh), and mutual conversions between Euclidean coordinates and differential coordinates. Further discussions about various strategies in both parts include a special subdivision method for mean-curvature normals, additional surface editing options, and a version of our framework for curve design. Finally, we demonstrate the improvement on surface quality by comparing the results between our framework and traditional subdivision methods.     

Accuracy of stereoscopic navigation system in flights above natural landscapes and urban land

Accuracy of stereoscopic navigation system designated for solution of problems of high accuracy navigation, guidance, and remote landscape probing is estimated. Linearization of photometric equations of the stereoscopic navigation system in the regime of stabilized horizontal flight of an aircraft is performed. Observation equations of the stereoscopic navigation system with account of the only stereo pair and a set of stereo images are determined. New algorithms of image processing in the stereoscopic navigation system based on the following two proved results: direct and inverse photogrammetry equations and the theory of joint optimal filtering, identification, and verification of hypotheses in a discrete dynamic system, are used to obtain formulas characterizing the accuracy of the stereoscopic navigation system in flights above natural landscapes and urban land. Procedure of choosing correction segments is considered.     

Modeling a nanowire superlattice using the finite difference method in cylindrical polar coordinates

A new procedure for handling periodic boundary conditions within the finite difference method and in cylindrical polar coordinates is presented and applied to modeling a nanowire superlattice. The method is compared for accuracy and efficiency with two other formulations of the same problem: the finite difference method applied to a finite number of unit cells, and the exact solution of the equivalent Kronig-Penney model. The technique is then shown to reproduce a novel physical state, and is applied to an embedded nanowire for which there are no analytical solutions.     

低成本有源RFID双向认证加密方案

针对射频识别(RFID)系统自身在认证和通信过程中存在的安全隐患问题,提出了一种低成本、高效、安全的RFID节点间身份认证与数据加密方案。该方案采用改进的椭圆曲线Diffie-Hellman(ECDH)算法与高级加密标准(AES)相结合的方式实现密钥分发、身份认证、通信加密功能,同时采用动态密钥算法增强了通信过程中的安全性。此外,该方案在不破坏安全强度的情况下缩减了运算规模,减少了系统资源开销。验证表明,该方案资源开销低,能够抵抗重放、假冒、中间人、拒绝服务等攻击,在对安全性能及低成本有一定要求的物联网领域具有一定的实用意义。     

Real-time detection of lines using parallel coordinates and CUDA

The Hough transform is a well-known and popular algorithm for detecting lines in raster images. The standard Hough transform is rather slow to be usable in real time, so different accelerated and approximated algorithms exist. This study proposes a modified accumulation scheme for the Hough transform, using a new parameterization of lines “PClines”. This algorithm is suitable for computer systems with a small but fast read-write memory, such as today’s graphics processors. The algorithm requires no floating-point computations or goniometric functions. This makes it suitable for special and low-power processors and special-purpose chips. The proposed algorithm is evaluated both on synthetic binary images and on complex real-world photos of high resolutions. The results show that using today’s commodity graphics chips, the Hough transform can be computed at interactive frame rates, even with a high resolution of the Hough space and with the Hough transform fully computed.     

单目平行线约束下的空间点坐标恢复

提出一种从单目像机拍摄的二维投影图像中恢复空间点三维坐标的简化算法.假定摄像机与空间中的一对平行线的位置关系已知,同时摄像机坐标系下平行线所在平面中的任意空间点在像平面中的投影也已知,通过射影几何可得图像坐标到目标点三维空间坐标的转换系数,即坐标转换因数,从而估计出三维空间点的坐标.实验中通过对人体行走轨迹进行估计来测试算法性能,结果表明算法简单有效,计算开销小.     

Low-cost rapid prototyping of glass microfluidic devices using a micromilling technique

A method is proposed for rapid prototyping of glass microfluidic devices utilizing a commercial micromilling machine. In the proposed approach, micromilling is performed with the glass substrates immersed in cool water, which could efficiently remove debris and increase the life of milling tools. We also investigate the effects of spindle speed, feed rate, cutting depth, cooling mode, and tool type on finished channel geometries, bottom surface roughness, and burring along the channel sides. It was found that low cutting depths, high spindle speeds and low feed rate produce smoother channels. Several functional microfluidic devices were demonstrated with this rapid prototyping method. The results confirm that the proposed micromilling technique represents a viable solution for the rapid and economic fabrication of glass-based microfluidic chips. We believe that this method will greatly improve the accessibility of glass microfluidic devices to researchers.