基于相频特性的具有光照鲁棒的人脸识别研究

传统人脸识别对人脸图像光照要求与人脸训练库差异不大,这提高了人脸识别系统运行的环境条件,限制了应用范围.为了降低人脸识别对环境条件的要求,克服光照对人脸识别的影响,分析了人脸图像的相频特性与光照的无关性,提出了基于相频特性的人脸识别,保留了人脸之间的可区分性.由于人脸之间可区分的信息量较少,运用最小非零特征向量作为人脸特征.实验仿真表明,与传统方法相比,提出的基于相频特性的人脸识别对光照变化具有鲁棒性.     

相机运动条件下的行人检测与跟踪

行人检测与跟踪在司机辅助安全系统和视频监控等领域具有重要的地位.针对目前存在的关键问题,如人体运动,相机运动,背景及形状、角度等变化对检测及跟踪带来的干扰,提出了一种将运动信息与形状信息相结合的行人检测方法,准确检测运动摄像机拍摄的直立运动人体;使用了基于小面积目标的跟踪算法进行人体跟踪;利用实际拍摄的视频序列进行算法验证.实验结果表明,混合检测算法速度快,准确率高;基于小面积的跟踪算法能够鲁棒的跟踪检测到的运动人体.     

面向不同数据分布的多维直方图算法COCA-Hist

基于代价的RDBMS优化器需要对含有范围查询的合取谓词的结果集基数进行准确的估计,多维直方图对多维数据分布进行模拟,避免在估计结果集基数时采用数据独立性假设,造成估计误差过大,进而导致选择非优化的查询执行计划.在不同的数据分布情况下,传统的多维直方图(如MHist-2)效果有很大不同.数据相关系数和值域密度、值域参数是准确刻画多维数据分布的有效指标,文中提出了根据不同的指标采用不同的动态优化的多维直方图算法COCA-Hist,可以大大改善传统多维直方图在平均情况下的准确性.通过分析传统的多维直方图的最坏情况,COCA-Hist的改进算法可以改进传统的多维直方图在最坏情况下的准确性.实验比较了COCA-Hist和传统的多维直方图MHist-2以及GENHist和STHoles的准确性和时间效率.实验显示无论在平均情况下还是在最坏情况下COCA-Hist的改进算法均优于传统的MHist-2直方图,并且COCA-Hist的准确性和创建时间均比GENHist有极大的改善,在准确性方面COCA-Hist较优于STHoles,而在空间预算有限时STHoles的创建时间比COCA-Hist高两个数量级.     

Content-based image retrieval using joint correlograms

The comparison of digital images to determine their degree of similarity is one of the fundamental problems of computer vision. Many techniques exist which accomplish this with a certain level of success, most of which involve either the analysis of pixel-level features or the segmentation of images into sub-objects that can be geometrically compared. In this paper we develop and evaluate a new variation of the pixel feature and analysis technique known as the color correlogram in the context of a content-based image retrieval system. Our approach is to extend the autocorrelogram by adding multiple image features in addition to color. We compare the performance of each index scheme with our method for image retrieval on a large database of images. The experiment shows that our proposed method gives a significant improvement over histogram or color correlogram indexing, and it is also memory-efficient.

Estimating aerodynamic resistance of rough surfaces using angular reflectance

Current wind erosion and dust emission models neglect the heterogeneous nature of surface roughness and its geometric anisotropic effect on aerodynamic resistance, and over-estimate the erodible area by assuming it is not covered by roughness elements. We address these shortfalls with a new model which estimates aerodynamic roughness length (z₀) using angular reflectance of a rough surface. The new model is proportional to the frontal area index, directional, and represents the geometric anisotropy of z₀. The model explained most of the variation in two sets of wind tunnel measurements of aerodynamic roughness lengths (z₀). Field estimates of z₀ for varying wind directions were similar to predictions made by the new model. The model was used to estimate the erodible area exposed to abrasion by saltating particles. Vertically integrated horizontal flux (F_h) was calculated using the area not covered by non-erodible hemispheres; the approach embodied in dust emission models. Under the same model conditions, F_h estimated using the new model was up to 85% smaller than that using the conventional area not covered. These F_h simulations imply that wind erosion and dust emission models without geometric anisotropic sheltering of the surface, may considerably over-estimate F_h and hence the amount of dust emission. The new model provides a straightforward method to estimate aerodynamic resistance with the potential to improve the accuracy of wind erosion and dust emission models, a measure that can be retrieved using bi-directional reflectance models from angular satellite sensors, and an alternative to notoriously unreliable field estimates of z₀ and their extrapolations across landform scales.     

光照模型中的亮度递推算法

本文提出了一种对ＧＯＵＲＡＵＤ浓淡模型的一种改进算法，在插值显示时采用亮度递推算法来考虑局部镜面反射的视觉效果。它利用一点的亮度来推算后一点的亮度。即考虑光源与观察点的各种布设关系，又考虑表面的骨程度引起的反射效应。该方法与实际模型较为一致，且显示速度快，可产生逼真的真实感图象。     

现代居室装修中的光污染

本文分析了室内环境中光污染产生的原因,提出了预防光污染的具体措施, 以寻求一些科学合理的照明方式,来指导实际装修中的照明设计。     

一种梯度方向直方图的人耳识别方法

为了提高多姿态人耳的识别准确率,提出了一种结合梯度方向直方图（H（）G）特征和监督保局投影的人耳识别方法．人耳图像被划分成重叠的子区域,在每个子区域中计算局部HOG特征．所有的局部HOG特征构造成包含丰富信息的高维向量,高维向量映射到流形空间利用监督保局投影进行鉴别分析,获得强鉴别力的特征．利用最小欧氏分类器进行分类识别．结果表明,本文方法提高了大姿态人耳的识别率．稀疏的子区域表示和局部HOG特征能在一定程度上克服姿态变化造成的对齐误差,对角度变化有很好的鲁棒性．     

The ‘corpuscle’ stereological problem—re-evaluation using slab fragment volumes and application to the correction of DNA histograms from sections of spherical nuclei

A new category of stereological size distribution unfolding models is introduced. It is based on the use of the volumes of particle slab fragments, in addition to their profile dimensions. When spheres are cut by a slab of known (constant) thickness, an estimation of discrete sphere sizes from section data is then possible, as only one parent sphere solution exists for any slab fragment, given the latter's projection size and volume. The unfolding algorithm consists in sequentially testing a set of equations: only one of the solutions satisfies various constraints on bounds. A precise determination of the section thickness is required. Truncation parameters, instead of being troublesome inputs as in classical unfolding models, become valuable outputs. This model offers the first stereologically valid solution to the important problem of correcting DNA-amount histograms obtained from sectioned spherical nuclei. Under the (biologically reasonable) assumption that the nuclear volume is proportional to the DNA amount, it is possible to estimate the DNA concentration and, subsequently, compute discrete slab fragment volumes from corresponding DNA values. An application to Feulgen-stained rat liver sections is shown. Measurements of hepatocytic nuclear-profile areas and integrated optical densities are obtained by automated image analysis (IBAS), and the model is used to unfold the section-obtained DNA histogram. A maximum likelihood fitting of the final distribution with chi functions allows a parametric estimation of ploidy frequencies. This model can only be used for acceptably spherically shaped particles.     

基于微信的蔬菜温室大棚环境监测系统设计

本文以STC89C52单片机为主控制器,应用温湿度传感器、土壤传感器、光照强度传感器以及Wifi模块等外围设备。通过传感器测量温室大棚中的室内环境参数,并与预设值进行比较,实时监测温室大棚中的各个环境参数。若当前值与预设值比较,当前值没有在预设值的范围内,则蜂鸣器报警,LED灯闪烁,并且外围设备自动打开,进行相应的工作。同时网络平台监测环境参数,当环境参数发生变换的时候,可实现网络平台对于外围设备的启停工作;最后,通过硬件设计和软件编程,实现了基于微信平台的温室大棚监测系统设计,达到预期效果。