珠线式模板在Freehand超声图像快速 标定中的应用*

为了精确标定freehand超声图像坐标系与固定于超声探头上的跟踪设备坐标系间坐标转换关系,提出一种“Z”形珠线模板,由双层“Z”形棉线与精确定位的圆珠构成。定位珠能够引导用户将探头准确定位,即将定位珠全部收入图像视野中。计算定位珠在超声图像中成像点间距的比例关系,根据其相应的模板空间间距比例制定优化算法,校准用户拾取的图像坐标。应用同源点匹配算法得到超声图像平面坐标系与磁跟踪设备坐标系间的空间转换关系,从而实现2-D超声图像向3-D空间坐标系的定位转换。标定结果显示此方法与以往的标定方法相比：加快了标定速度,且标定精度与重建精度有所提高。试验采用磁定位方式进行探头的跟踪定位,此方法同样适用于其他定位方式。     

浅析当今写意青花的题材选择

青花装饰是景德镇的传统装饰方法之一，其中的写意青花又以其简约萧疏的艺术特征获得了人们的普遍喜爱。针对时代的变化影响，研究了当今写意青花在题材选择上与传统写意青花的差异。     

Real Time Fitting of Hand-Sketched Pressure Brushstrokes

A method is described for fitting the outline of hand-sketched pressure brushstrokes with Bézier curves. It combines the brush-trajectory model, in which a stroke is generated by dragging a brush along a given trajectory, with a fast curve fitting algorithm. The method has been implemented for a vector-based drawing program in which the user draws with a cordless pressure-sensitive stylus on a digitizing tablet. From the trajectory followed by the stylus, its associated pressure data, and a specified brush, a stroke of variable width is computed and displayed in real time. First, the digitized trajectory is fitted, thus removing noise. Then, from polygonal approximations of the fitted trajectory and the brush outline, a polygonal approximation of the stroke outline is computed. Working with polygonal approximations reduces computations to simple geometric operations and greatly simplifies the treatment of dynamic, pressure-controlled brushes. Last, the polygonal approximation of the stroke outline is fitted. The result is a closed piecewise Bézier curve approximating the brushstroke outline to within an arbitrary error tolerance. Several examples of hand-sketched drawings realized with this method are presented.     

手绘草图实时处理方法研究

徒手草绘作为一种简便、自然、高效的人机交互方式，在计算机辅助设计领域越来越受到人们的重视。本文主要针对草绘设计与图形识别的行为过程进行了一系列较为广泛的研究，以便将用户的草绘习惯、识别能力与现有的CAD技术紧密结合起来，开发出新一代的智能CAD产品。具体包括草图前处理、特征点的检测、笔划分段、图元识别、图元重构、图元规整、端点校正等内容。实验表明所提出的方法能得到较好的识别结果。     

手绘草图实时处理方法研究

徒手草绘作为一种简便、自然、高效的人机交互方式,在计算机辅助设计领域越来越受到人们的重视。本文主要针对草绘设计与图形识别的行为过程进行了一系列较为广泛的研究,以便将用户的草绘习惯、识别能力与现有的CAD技术紧密结合起来,开发出新一代的智能CAD产品。具体包括草图前处理、特征点的检测、笔划分段、图元识别、图元重构、图元规整、端点校正等内容。实验表明所提出的方法能得到较好的识别结果。     

概念图形草绘设计技术研究

针对概念草图的输入输出问题,采用了基于草绘输入的交互式图形设计方法,实现了单笔划草绘轨迹主动分段识别与规整方法;运用了基于笔式手势的草图编辑方法,并将概念草图以DXF的格式输出,实现与现有CAD系统之间的集成.根据手势设计原则以及草图编辑的需要,定义并实现了选择、删除、移动等10种手势,同时采用感知器线性分类方法对手势进行识别.实例表明:手势编辑模式能够改善传统编辑方式在自然性与智能性方面的不足.     

北方艺术一体化运用研究--写意花鸟画与印章

在当前国画创作趋于写实甚至超写实的状态下。北方写意花鸟画从其正大气象绝能独立,给画坛带来了强劲的“东北风”和浓郁的时代气息。北方写意花鸟之作无不凌射着北方的粗犷奔流之气以及旺盛难抑的生命之气,小中见大．将人引入高处不胜寒的祟高美学境界之中。然当欣赏者或学术研究者都侧重于画作的孤枣以及独到的笔墨关系的时候,都极容易忽略印章一一篆刻艺术在其画作中所起到的无可替代的重要作用。     

Surgical tool motion during conventional freehand and robot-assisted microsurgery conducted using neuroArm

Surgical tool motion during microsurgery could arguably reflect surgical performance. This paper reports on how the motion of a surgical tool correlates or differs between conventional freehand surgery and robot-assisted surgery. In this pilot study, components of the position and orientation as well as the linear and angular velocities of a surgical tool, over the same period of operation, are compared during the two scenarios. For freehand surgery, a bipolar forceps is retrofitted with a tracking system to measure translational and rotational components of the tool motion. In robot-assisted surgery, the position and orientation components are obtained using kinematics of the neuroArm image-guided robotic system. A cross correlation analysis was used to investigate correlation between each pair of displacement or velocity components from freehand and robot-assisted scenarios to indicate how strongly or weakly two sets of data are linked together. The absolute maximum value of the cross correlation coefficient is calculated for each pair of components to quantitatively investigate the correlation between two sets of data. Results showed that the positional and rotational components, reflecting the surgical workspace, in both scenarios are correlated. However, for the cases studied, surgical tool rate of motion differs between the two scenarios. Results are important as they can be utilized to design robot-assisted neurosurgical systems that reflect characteristics of freehand surgery gained by surgeons through years of training, knowledge, and experience.     

浅议建筑美术教学实习的体会

该文通过介绍作者带建筑学专业学生到山西平遥教学实习,以13幅建筑徒手画和建筑写生为示范,提出了建筑徒手画和写生要注意的建筑准确性,建立较好的画面感,表现建筑与环境的关系,提高建筑修养和艺术素养等三个层次目标,并强调应用"简宜繁之,繁宜简之"的处理画面的技法。     

建筑师的徒手绘画基本功

阐述了徒手草图、速写等基本功对建筑师来说是非常重要和必须的，指出通过大量的徒手训练,厅以提高绘画技巧、积累大量经验，提高思维想象能力的工作效率。