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WU Lu-shen PENG Qing-jin 《浙江大学学报(A卷英文版)》2006,7(6):1026-1036
INTRODUCTION Geometric modelling is essential processing in computer-aided engineering (CAE) systems. Usually, the modelling of three-dimensional (3D) objects is embedded in a computer-aided design (CAD) system, which may take a huge amount of time to build entire models for CAE application. One option is the use of techniques of reverse engineering (RE) to build models from existing objects. Coordinate measuring machines (CMMs) are traditional RE tools used in the manufacturing i… 相似文献
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针对雾气分布不均匀的交通监控图像去雾,提出了一种基于近似点扩展函数估计-APEX的去雾算法。算法采用APEX的基本原理,利用暗原色先验求出的有雾图像透射图对APEX参数进行估计,且估计值按整幅图像的雾气浓度分布自适应调整,再计算出点扩展函数并逆运算得出复原的清晰图像。实验结果证明,该算法实时性高且去雾效果好,特别是对雾气分布不均匀的交通图像也有去雾效果,能满足智能交通监控系统的需求。 相似文献
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陈曼华 《金陵科技学院学报(社会科学版)》2002,(1)
提出了一种逆时针追踪轮廓线的彩色图像区域分割算法 ,其思想是按逆时针顺序追踪轮廓线 ,在追踪过程中避免了象素点的重复判断 ,采用回溯搜索解决奇点问题 ,从而保证了追踪过程的连续性和正确性。在此基础上 ,运用递归方法分割出图像的所有不同色彩区域。直接提取出具有一定色彩特征的区域 ,具有较高的实用性 ,也是此算法的优点之一 相似文献
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高精度在线计算轮廓误差可有效降低数控加工中的控制轮廓误差。因此,提出一种基于三点弧线理论的方法,在补偿轮廓误差之前对轮廓误差进行精确计算。首先根据插值参考位点与加工过程中的实际位置,计算距离实际位置最近的参考位点;然后根据最近参考位置及其相邻两点形成的近似外接圆弧,计算实际位置到该圆弧的距离,即求得刀尖位点轮廓误差,采用同样方法计算刀具方向轮廓误差。实验结果表明,该算法比原有算法刀尖位点轮廓误差均值减小了 0.056um,刀具方向均值比原有算法减少 7.166um。基于三点弧线理论的算法仅需考虑实际位置与距离实际位置最近的参考位点坐标,可精确计算较大的曲率处,且无需考虑传统计算方法中刀具干涉问题,简化计算过程的同时还可保证计算精度。 相似文献
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图像风格迁移技术是指给定内容图和风格图,利用机器学习算法将内容图渲染成具有艺术风格的画作。针对传统图像风格迁移算法无法兼顾速度与生成图像质量等问题,基于 AdaIN 算法,提出 AdaIN 改进算法。在原始 AdaIN 网络中加入内容图像的深度信息计算模块,提取内容图像的深度图,通过将迁移图像数据与深度图归一化处理后的数据按元素相乘的方法,突出内容图的深度信息,使得输出的风格迁移图像各深度下具有不同的风格化程度。实验表明,相较于 Gatys 等种传统风格迁移算法,AdaIN 改进算法在运行时间上可降低约 11%;不需要针对每种风格单独训练网络,避免了模型重复训练;内容图像深度信息得以保存,提高了图像渲染质量。 相似文献
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吴霆 《广东轻工职业技术学院学报》2011,10(2):18-21
研究了基于图像处理的工件轮廓检测技术的流程及算法,通过图像滤波、图像增强、阈值分割、边缘检测、边缘定位和参数测量及拟合等一系列算法,可以测出被检测工件是否符合要求及其误差范围。 相似文献
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Autofocus method based on the analysis of image content information is investigated to reduce the alignment error resulting from mark positioning uncertainty due to defocus in microstructure layered fabrication process based on multilevel imprint lithography, The applicability of several autofocus functions to the alignment mark images is evaluated concerning their uniformity, sharpness near peak, reliability and measure computation efficiency and the most suitable one based on power spectrum in frequency domain (PSFD) is adopted. To solve the problem of too much computation amount needed in PSFD algorithm, the strategy of interested region detection and effective image reconstruction is proposed and the algorithm efficiency is improved. The test results show that the computation time is reduced from 0.316 s to 0.023 s under the same conditions while the other merits of the function are preserved, which indicates that the modified algorithm can meet the mark image autofocusing require-ments in response time, accuracy and robustness. The alignment error due to defocus which is about 0.5 μm indi-cated by experimental results can be reduced or eliminated by the autofocusing implementation. 相似文献
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在缺陷检测过程中,由于光照角度和亮度等因素导致采集的图像亮度较小,对比度不明显,使用一般相机采集某些材料表面图像时不能取得较好的效果。工业相机成像质量通常高于普通相机,因此利用Basler工业相机获取丝绸材料表面缺陷,基于图像处理缺陷检测技术提取丝绸表面缺陷图像。首先对图像进行灰度转换,得到单通道灰度图像,以便进行图像二值化处理。由于二值化图像有噪声点,用简单的模糊处理无法有效消除,需对图像进行开运算。将图像腐蚀后再进行膨胀,基本上可解决图像噪声问题,根据最后提取的图像轮廓进行筛选,提取出轮廓缺陷。经过检测发现,该算法对工业工件表面缺陷提取更准确,效果更好,可高效检测丝绸表面缺陷,提高生产效率。 相似文献
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为了解决低对比度成像条件下传统三维轮廓重建算法精度偏低的问题,提出一种基于邻域距离最小化准则、由粗到细的高精度轮廓三维重建算法。首先使用 Canny 算子对目标图像进行边缘检测,再利用目标形状、尺寸等先验信息剔除分割出的虚假目标边缘。随后,计算边缘点法线方向上的梯度加权值作为工件初始化轮廓,根据左右一致性原则筛选出粗匹配点对,在匹配点对邻域附近使用亚像素进行精细搜索,利用邻域距离最小化准则估算出当前最佳亚像素匹配点对,并将其用于激光刻形工件的尺寸测量,总体精度可达 0.1mm。该方法有效降低了轮廓重建算法对边缘定位精度的依赖,同时提高了轮廓重建精度。 相似文献
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为了解决传统算法QR码定位中出现QR码失真,或旋转时出现较弱鲁棒性的现象,提出一种新型QR码自适应定位算法。在算法研究过程中,首先使用自适应阈值算法解决不均匀照明的影响,在此基础上提出一种基于轮廓跟踪与轮廓筛选的定位方法。实验结果表明,与传统QR码定位算法相比,该算法定位准确率提高了30%,且定位速度提升了17%,可见该定位算法能够很好地应用于QR码定位。 相似文献
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INTRODUCTION Image segmentation plays an essential role in jacquard image analysis. A jacquard image consists of many complex patterns which contain detailed, in- tricate topological curves. An accurate extraction of pattern features from jacquard images promises reli- ability for jacquard fabric CAD. Although, many algorithms have been proposed for the segmentation problem, they have difficulty in capturing the com- plex structure of the visual features, such as complex contours of a ja… 相似文献
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Automatic segmentation of bladder in CT images 总被引：1，自引：0，他引：1
Segmentation of the bladder in computerized tomography （CT） images is an important step in radiation therapy planning of prostate cancer. We present a new segmentation scheme to automatically delineate the bladder contour in CT images with three major steps. First, we use the mean shift algorithm to obtain a clustered image containing the rough contour of the bladder, which is then extracted in the second step by applying a region-growing algorithm with the initial seed point selected from a line-by-line scanning process. The third step is to refine the bladder contour more accurately using the rolling-ball algorithm. These steps are then extended to segment the bladder volume in a slice-by-slice manner. The obtained results were compared to manual segmentation by radiation oncologists. The average values of sensitivity, specificity, positive predictive value, negative predictive value, and Hausdorffdistance are 86.5%, 96.3%, 90.5%, 96.5%, and 2.8 pixels, respectively. The results show that the bladder can be accurately segmented. 相似文献
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阐述现阶段品牌服装防伪现状及应用二维条码在服装吊牌上的可行性。针对商标图像以色块图为主、颜色少的特点,在对商标图像进行边缘检测、轮廓跟踪及轮廓特征信息提取的基础上,提出了一种商标图像大比例压缩算法,实现将服装吊牌中商标和服装其他特征信息制成一种带PDF417二维条形码的服装吊牌。通过识读出二维条码中的服装文字信息及商标图案和服装吊牌上信息相对比,实现服装吊牌的防伪。 相似文献
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为避免相邻图像非重叠区域特征点被检测和提取,加速图像配准,提出一种基于相位相关法与改进SURF算法的快速图像拼接方法。该方法采用相位相关算法确定待拼接图像的重叠区域,限定SURF特征点检测、提取范围,用改进的SURF算法进行特征点匹配|然后根据MSAC算法剔除误配后的特征点匹配对,求取单应性矩阵,实现图像之间的快速配准|最后采用多波段融合算法对配准后的图像进行处理以消除拼接缝。实验结果表明,与传统算法相比,该方法可提高特征点匹配正确率,加速图像配准过程,完成拼接图像间的平滑过渡。 相似文献
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分析地理信息系统(GIS)、北斗卫星导航、GPS、位置信息服务、移动互联网传输等技术在交通物流中的应用,提出基于移动互联网与GIS的预警图像传输优化方法。物流运输监测预警图像适配视频传感器在动态检测图像上结合Exif信息匹配地理信息坐标位置网点,采用哈夫曼编码进行图像压缩、运动检测算法处理图像冗余,并采用纹理合成的匹配块图像修复失真等方法还原图像数据,最终实现不同空间地理位置的地图查询、路径搜索、位置检索、地图匹配等交通物流过程动态控制,并通过Matlab仿真实验证明了传输优化的可行性。 相似文献
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《Contemporary educational psychology》1998,23(1):22-41
Contour map learning may require three-dimensional representation of the area depicted by a contour map. The purpose of the study was to test the hypothesis that participants created three-dimensional mental representations of contour maps when asked to generate a cross-section profile of the map terrain from one point on the contour map to another. Gender differences in cross-section performance were also investigated, and it was hypothesized that males would perform better than females in a contour map cross-section test. Participants studied a series of contour maps or landsurface maps (three-dimensional drawings of an area), and answered two cross-section questions per map. Following the cross-section test, participants were given an incidental recognition test for the previously studied maps, either in a contour map format or a landsurface map format. Males recognized the landsurface maps corresponding to the contour map cross-section questions answered correctly better than contour map cross-section questions answered incorrectly, whereas females did not. This finding suggested that males, but not females, formed three-dimensional representations of the contour maps. There were no gender differences in performance on the contour map cross-section test, but males achieved higher recognition scores than females when the cross-section stimuli were contour maps. It was concluded that multiple spatial and verbal processing strategies can be used successfully to solve a contour map cross-section test, but that three-dimensional spatial processing may be more efficient than other forms of processing for long-term memory of contour maps. 相似文献
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SLAM is one of the most important components in robot navigation. A SLAM algorithm based on image sequences captured by a single digital camera is proposed in this paper. By this algorithm, SIFT feature points are selected and matched between image pairs sequentially. After three images have been captured, the environment＇s 3D map and the camera＇s positions are initialized based on matched feature points and intrinsic parameters of the camera. A robust method is applied to estimate the position and orientation of the camera in the forthcoming images. Finally, a robust adaptive bundle adjustment algorithm is adopted to optimize the environment＇s 3D map and the camera＇s positions simultaneously. Results of quantitative and qualitative experiments show that our algorithm can reconstruct the environment and localize the camera accurately and efficiently. 相似文献
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陈铁冰 《深圳职业技术学院学报》2009,8(3):38-41
文章提出基于神经网络重要抽样法的结构可靠度评估方法,该方法通过训练神经网络,建立随机变量与结构响应之间的非线性映射关系,模拟结构极限状态方程,采用优化算法计算设计点．在重要抽样法中利用训练好的神经网络代替有限元求解器进行数值计算．结果表明,所训练的神经网络能够有效地模拟真实的结构极限状态方程,结构失效概率计算结果具有很高的精度,调用有限元分析的次数显著减少,有效地提高了计算效率． 相似文献