LIC color texture enhancement algorithm for ocean vector field data based on HSV color mapping and cumulative distribution function

Texture-based visualization method is a common method in the visualization of vector field data.Aiming at adding color mapping to the texture of ocean vector field and solving the ambiguity of vector direction in texture image,a new color texture enhancement algorithm based on the Line Integral Convolution(LIC)for the vector field data is proposed,which combines the HSV color mapping and cumulative distribution function calculation of vector field data.This algorithm can be summarized as follows:firstly,the vector field data is convoluted twice by line integration to get the gray texture image.Secondly,the method of mapping vector data to each component of the HSV color space is established.And then,the vector field data is mapped into HSV color space and converted from HSV to RGB values to get the color image.Thirdly,the cumulative distribution function of the RGB color components of the gray texture image and the color image is constructed to enhance the gray texture and RGB color values.Finally,both the gray texture image and the color image are fused to get the color texture.The experimental results show that the proposed LIC color texture enhancement algorithm is capable of generating a better display of vector field data.Furthermore,the ambiguity of vector direction in the texture images is solved and the direction information of the vector field is expressed more accurately.

Rapid Texture Mapping from Image Sequences for Building Geometry Model

An effective approach, mapping the texture for building model based on the digital photogrammetric theory, is proposed. The easily-acquired image sequences from digital video camera on helicopter are used as texture resource, and the correspondence between the space edge in building geometry model and its line feature in image sequences is determined semi-automatically. The experimental results in production of three-dimensional data for car navigation show us an attractive future both in efficiency and effect.

Realization of 3D Garment Rendering Using Texture Mapping Technology

After a review of the planar garment effect production of pattern fabric and a brief introduction of the concept of texture mapping, the theory of 2D texture mapping onto 3D surface is stated. And the calculation procedures of texture mapping, such as texture image preprocess,mannequin and garment surface modeling, mapping relationship definition, shading/texturing model creation, and graphic transformation,are exploited to produce a real 3D garment rendring effect.Finally, the conclusion is given about the realization envlronment and affecting factors of the final images.

Development of Texture Mapping Approaches for Additively Manufacturable Surfaces

manufacturing(AM)technologies have been recognized for their capability to build complex components and hence have ofered more freedom to designers for a long time.The ability to directly use a computer-aided design(CAD)model has allowed for fabricating and realizing complicated components,monolithic design,reducing the number of components in an assembly,decreasing time to market,and adding performance or comfort-enhancing functionalities.One of the features that can be introduced for boosting a component functionality using AM is the inclusion of surface texture on a given component.This inclusion is usually a difcult task as creating a CAD model resolving fne details of a given texture is difcult even using commercial software packages.This paper develops a methodology to include texture directly on the CAD model of a target surface using a patch-based sampling texture synthesis algorithm,which can be manufactured using AM.Input for the texture generation algorithm can be either a physical sample or an image with heightmap information.The heightmap information from a physical sample can be obtained by 3D scanning the sample and using the information from the acquired point cloud.After obtaining the required inputs,the patches are sampled for texture generation according to non-parametric estimation of the local conditional Markov random feld(MRF)density function,which helps avoid mismatched features across the patch boundaries.While generating the texture,a design constraint to ensure AM producibility is considered,which is essential when manufacturing a component using,e.g.,Fused Deposition Melting(FDM)or Laser Powder Bed Fusion(LPBF).The generated texture is then mapped onto the surface using the developed distance and angle preserving mapping algorithms.The implemented algorithms can be used to map the generated texture onto a mathematically defned surface.This paper maps the textures onto fat,curved,and sinusoidal surfaces for illustration.After the texture mapping,a stereolithography(STL)model is generated with the desired texture on the target surface.The generated STL model is printed using FDM technology as a fnal step.

Bidirectional Texture Mapping

Texture mapping is an important technique for high -quality image generation in computer graphics. In this paper, the shortcoming of the traditional texture mapping approaches is analysed and a general bidirectional texture mapping method is proposed. Based on the bidirectional mapping, an algorithm for mapping an image to an arbitrary polygon in 3D space is given.

Constructive Texture Steganography Based on Compression Mapping of Secret Messages

This paper proposes a new constructive texture synthesis steganographic scheme by compressing original secret messages.First,we divide the original message into multiple bit blocks,which are transferred to decimal values and compressed into small decimal values by recording their interval sign characters.Then,a candidate pattern is generated by combining the given source pattern and boundary extension algorithm.Furthermore,we segment the candidate pattern into multiple candidate patches and use affine transformation algorithm to locate secret positions on a blank canvas,which are used to hide the sign characters by mapping the candidate patches.Finally,we select the candidate patches with minimal mean square error to represent secret bits to generate stego image by image quilting.Extensive experiments demonstrate that compared with existing texture steganographic methods,our method has a better visual quality,higher embedding capacity and security performance,while maintaining strong anti-steganalysis capability.

T2 mapping影像组学特征鉴别乳腺病灶良恶性的临床应用初探

目的探讨基于磁共振T2 mapping的影像组学特征在预测乳腺病灶良恶性中的应用价值。材料与方法回顾性分析经病理证实的113例患者(良性51例,恶性62例)乳腺磁共振T2 mapping图像,应用ITK-SNAP软件手动勾画磁共振T2 mapping图像中的病灶感兴趣区,利用A.K.软件(AnalysisKit,GE Healthcare)对影像组学特征进行提取。根据病理结果,将其分为两组。通过组内相关系数进行一致性检验。在良性组、恶性组中通过7∶3的比例随机分割训练集与测试集。通过Z-score标准化处理、Pearson相关系数法、递归特征消除法对训练集进行特征降维及选择,逻辑回归分类器进行分类建模,并进行5折交叉验证。分别在训练集及测试集中绘制受试者工作特征(receiver operating characteristic,ROC)曲线,以评估模型的诊断效能,通过临床决策曲线分析(decision curve analysis,DCA)评价其临床有效性。结果通过特征提取获得107个定量影像特征参数,通过特征降维及筛选最终保留6个特征参数,分别为original_shape_Sphericity、original_glcm_InverseVariance、original_glrlm_GrayLevelNonUniformityNormalized、original_glrlm_ShortRunEmphasis、original_glszm_GrayLevelNonUniformity Normalized以及original_ngtdm_Coarseness。ROC曲线在测试集的曲线下面积为0.895(95%可信区间:0.768~0.990),敏感度为94.7%,特异度为80.0%,准确度为88.2%。结论基于磁共振T2 mapping的影像组学特征可用于术前预测乳腺病灶的良恶性,且具有较高的准确度。

Self-similarity Based Editing of 3D Surface Textures Using Height and Albedo Maps

This paper presents an inexpensive method for self-similarity based editing of real-world 3D surface textures by using height and albedo maps. Unlike self-similarity based 2D texture editing approaches which only make changes to pixel color or inten- sity values, this technique also allows surface geometry and reflectance of the captured 3D surface textures to be edited and relit us- ing illumination conditions and viewing angles that differ from those of the original. A single editing operation at a given location affects all similar areas and produces changes on all images of the sample rendered under different conditions. Since surface height and albedo maps can be used to describe seabed topography and geologic features, which play important roles in many oceanic proc- esses, the proposed method can be effectively employed in applications regarding visualization and simulation of oceanic phenom- ena.

利用面片阴影法简化Bump Mapping

论文介绍了Bump Mapping的生成方法,并针对可分割bump形式的纹理提出了利用OpenGL简化计算和加速显示的方法———面片阴影算法,即利用面片的阴影降低逐点计算的复杂性。

3.0 T MRI T2 mapping纹理特征在膝关节骨性关节炎软骨损伤分级中的价值

目的探究基于3.0 T MRI T2 mapping的纹理特征在膝关节骨性关节炎(keen osteoarthritis,KOA)患者不同程度软骨损伤分级中的诊断性能。材料与方法回顾性分析实验组骨性关节炎患者72个膝关节及对照组健康志愿者22个膝关节。通过矢状位T2 mapping生成T2伪彩图,在T2伪彩图中画取ROI并标记国际软骨修复学会(International Cartilage Repair Society,ICRS)分级,选取ICRS MRI分级与关节镜分级一致的201个关节面图像,采用OK软件提取、分析纹理参数。按7∶3的比例随机选取143个关节面图像作为训练集,剩余58个关节面图像作为验证集。对训练集的参数用Spearman及sbf(select by filter)进行特征过滤,用随机森林函数进行特征选择,用ctree建立模型,给出特征在鉴别正常软骨及不同软骨损伤分级中的权重。用曲线下面积(area under the curve,AUC),敏感度、特异度,准确度来评价模型预测正常软骨及不同软骨损伤分级的性能。结果MinLocation、MaxSize及Maximun3DDiameter权重均一致较大,其中MinLocation在各损伤分级中权重均最大,超过0.75。集训集中正常软骨的AUC值为0.91,Ⅰ级损伤的AUC值为0.82,Ⅱ级损伤的AUC值为0.84,Ⅲ级损伤的AUC值为0.88;验证集中正常软骨的AUC值为0.87,Ⅰ级损伤的AUC值为0.74,Ⅱ级损伤的AUC值为0.84,Ⅲ级损伤的AUC值为0.96。AUC最高的是验证集中Ⅲ级损伤软骨,为0.96;其次是训练集中正常软骨,为0.91。无论在训练集还是验证集中都表现出了良好的预测价值。敏感度最高的是训练集中Ⅰ级损伤软骨,为0.83;特异度最高的是训练集中Ⅲ级损伤软骨,为0.98。结论通过T2 mapping提取的纹理参数在不同软骨损伤程度中有较好的鉴别能力。

Bump Mapping原理及在OpenGL下的实现

凹凸映像(bump mapping)作为逐像素光照的一种,能够非常逼真地再现物体表面的细节。文章在对传统光照模型分析的基础上,比较了Gouraud光照模型和Phong模型。并结合目前主流的3D图形硬件,说明了实现Phong光照模型的可行性。然后介绍了逐像素光照、法线图、切面空间、Cube-Map等实现凹凸映像的要素,最后阐述了在OpenGL下实现bump mapping的步骤。

Textures of high-strength and low-expansion Fe-Ni alloy wires during cold-drawing processes

Textures of high-strength and low-expansion Fe-Ni alloy wires during cold-drawing processes were investigated using X-ray diffraction （XRD） and electron back scatter diffraction （EBSD） techniques. The experimental results show that the 〈111〉 and 〈100〉 fibre textures are the main texture components, and crystalline grains in the surface are more fine and uniform than those in the center of Fe-Ni alloy wires during cold-drawing processes. It is found that the volume fraction of the 〈111〉 fibre texture component determined by quantitative regression calculation of the Gaussian distribution function reaches more than 60% and the strong 〈111〉 fibre texture component favors the torsional property of Fe-Ni alloy wires.

Looking at the Statistical Texture Approach Applied to Weather Radar Rainfall Fields

Texture analysis methods have been used in a variety of applications, for instance in remote sensing. Though widely used in electrical engineering, its application in atmospheric sciences is still limited. This paper reviews some concepts of digital texture and statistical texture approach, applying them to a set of specific maps to analyze the correlation between texture measurements used in most papers. It is also proposed an improvement of the method by setting free a distance parameter and the use of a new texture measurement based on the Kullback-Leibler divergence. Eight statistical measurements were used: mean, contrast, standard deviation, cluster shade, cluster prominence, angular second moment, local homogeneity and Shannon entropy. The above statistical measurements were applied to simple maps and a set of rainfall fields measured with weather radar. The results indicate some high correlations, e.g. between the mean and the contrast or between the angular second moment, local homogeneity and the Shannon entropy, besides the potentiality of the method to discriminate maps.

PATTERN MAPPING ON BETA-SPLINE SURFACES——BILINEAR MAPPING METHOD

Texture pattern mapping is one of the most important techniques for high quality image syn- thesis. It can largely enhance the visual richness of raster-scan images. In this paper is presented a new method of mapping planar texture pattern onto beta-spline curved surfaces——bilinear mapping method which can map planar texture pattern onto curved surfaces with less distortion, and also can fulfill the geometric transformation of the texture pattern on the curved surfaces by operating the pattern win- dow. It is valuable to both CAD/CAM in artistic field and computer graphics.

PATTERN MAPPING ON FREE-FORM SURFACES——CF MAPPING METHOD

In this paper a new method of texture pattern mapping onto free-form surfaces with less distortion and higher suitability is presented.This named CF Mapping Method is based on the Ap- proximate Development Principle and Equidistance Correspondence Rule.It is adaptable to various kinds of free-form surfaces with slight warping.Especially,by operating the pattern window ,dif- ferent artistic treatments——translation,rotation,reflection,sealing,etc.can be fulfilled.Undoubt- edly,it is very practical in the CAD/CAm of artistic scope.

一种带高光处理的无缝纹理映射方法

纹理映射作为三维重建的重要步骤,直接关系到生成模型的视觉效果。传统的纹理映射方法通常使用简单的混合方法来获取表面纹理。通过将模型表面投影到每个纹理图像上来获取相应的纹理区域,然后将它们混合在一起以获取表面纹理。然而,由于相机位姿的不准确性,纹理映射结果存在明显的模糊和鬼影等问题。此外,在高光环境下获取的纹理图像很容易包含高光区域,最终导致纹理颜色的丢失,降低纹理的真实性。为了解决这些问题,提出了一种无缝纹理映射方法,可以有效消除高光反射。通过衡量纹理图像的质量,为每个模型表面选择最佳的纹理图像,并利用色度一致性约束优化的相机位姿以消除明显的纹理错位。针对高光问题,提出了一个高光处理模块,使用多视图图像信息并基于双色反射模型定位和处理高光纹理。最后,对纹理图进行纹理颜色一致性调整,以处理纹理之间的颜色差异。实验结果表明,与现有方法相比,提出的算法可以有效消除高光反射的影响,从而获得更好的纹理映射结果。

基于MAP的单帧字符图像超分辨率重建

字符是很多图像处理应用关注的区域,增强字符图像分辨率往往能提高字符识别率.针对字符图像纵横和对角线方向纹理特征,提出了一种提取不同方向纹理及图像平滑度度量的新方法,并在最大后验概率框架下,实现了单帧图像超分辨率重建算法.算法利用自适应可调模板作为卷积核,将纹理信息引入图像先验模型,最终将超分辨率重建转化为一个目标函数最优化问题.实验表明,该算法能有效提高字符图像的识别率,且对噪声具有较好的鲁棒性.

一种新的基于MAP的纹理自适应超分辨率图像复原算法

本文论证了超分辨率图像复原计算中的两个性质,并基于此在MAP(Maximum A Posteriori)框架下提出了一种新的纹理自适应算法.算法首先根据低分辨率图像和高分辨率图像近似计算的可类比性质计算初始图像,使初始图像的质量更高,并根据超分辨率复原图像阶跃边缘的陡坡性质,将三边滤波正则化应用于迭代运算中,更好地保护了图像的陡坡和屋顶边缘.算法可根据图像的纹理自动计算初始图像融合参数以及正则化函数中的梯度阈值等参数,解决了以往超分辨率图像复原算法参数调整复杂的问题.实验结果表明,本文算法在没有人工参与的情况下,重建图像的客观评价和主观质量均有明显提高.

Mipmap映射技术中d值计算方法的探讨

在Mipmap技术中,常常用一个正方形来近似表示象素在纹理空间的投影,通过正方形的边长d与Mipmap标准采样使用的正方形过滤器的D进行比较,查找Mipmap表。由于象素的投影常是不规则的,求解这个近似正方形的边长d也是不容易的。文中分析了Mipmap预过滤的原理和常用d值的求取办法,提出了一个采用四边形对角线求取近似正方形边长d的方法,并对该方法进行了探讨。

无先兆性偏头痛患者力敏腧穴分布规律及红外特征研究

目的:观察无先兆性偏头痛(MO)患者和健康受试者力敏腧穴体表分布情况,分析MO患者力敏腧穴分布规律及红外温度特征。方法:选取2019年12月至2022年3月就诊于江西中医药大学附属医院的60例MO患者和60例健康受试者作为研究对象,对120例研究对象进行体表力敏腧穴探查并记录,分析总结MO患者力敏腧穴分布与经脉、神经节段的位置关系;运用红外热成像技术(TTM)观察总结MO患者力敏腧穴红外特征。结果:MO组体表力敏腧穴出现率为88.3%(53/60),健康组为6.67%(4/60,P<0.01)。MO组力敏腧穴主要分布于胆经、肝经以及三焦经,率谷、风池、太冲穴区敏化率较高。MO组力敏腧穴多分布于三叉神经、C_(2)、C_(7)神经节段。力敏腧穴红外温度及部位特征表现为:MO患侧>MO健侧>健康受试者,MO患者颞部、目额部、后头部、前臂外侧、足背部力敏腧穴存在明显不规则热源分布。结论:MO患者力敏腧穴与传统经脉、神经节段位置密切相关,红外温度升高、体表不规则红外热源分布是其重要特征。