基于红外光源的驾驶员眼睛实时监测

眼睛检测是驾驶员疲劳监测系统的关键技术，人眼包含了驾驶员的很多信息，如视线、注意程度、疲劳程度。该文提出了一种不同光照情况下新的实时检测眼睛的方法。通过使用红外光源和基于外观的物体识别技术简化了对眼睛的检测，在不同天气环境下图像特性比较一致，保证了不同气候状况下的亮瞳效应。     

三维烟雾的实时模拟

提出了一种基于流体力学方程并采取欧拉法实时模拟三维真实感烟雾的算法。通过Navier-Stokes方程建立烟雾流场的物理模型,以保证视觉的真实感。为了保证运算的实时性,烟雾流场划分为三维网格空间,并将烟雾速度场的分布定义于每个立方网格单元的中心点;通过线性插值获取整幅图像中每个像素的烟雾浓度。将烟雾模拟技术用于图像的显示特技中,以产生图像消散成烟雾的视觉效果,得到了比较满意的模拟效果。     

An Efficient Radiosity Approach for Realistic Image Synthesis

The radiosity method models the interaction of light between diffusely reflecting surfaces and accurately predicts the global illumination effects. Procedures are now available to simulate complex environments including occluded and textured surfaces. For accurate rendering, the environment must be discretized into a fine mesh, particularly in areas of high intensity gradients. The interdependence between surfaces implies solution techniques which are computationally intractable. This article describes new procedures to predict the global illumination function without excessive computational expense. Statistics indicate the enormous potential of this approach for realistic image synthesis, particularly for dynamic images of static environments.     

主动队列管理中PI与PID算法的仿真研究

主动队列管理机制是一个非常活跃的研究领域.在Hollot论文里用线性控制理论模型化TCP的基础上,采用NS仿真平台设置网络仿真场景,对主动队列管理机制中的PI和PID这两种典型算法进行了仿真研究.还介绍了NS模拟器的结构和利用模拟器进行网络仿真的一般步骤.文中的仿真实验设置了不同的实验条件,采用了异质流来模拟真实的网络场景,验证和比较了PI及PID控制算法在主动队列管理机制中的性能.通过NS-2模拟器模拟表明,PID算法的快速性优于PI算法,而PI算法的鲁棒性则比PID更好.     

一种基于颜色拮抗感受野的轮廓检测模型

轮廓检测在目标识别、图像分割和模式识别等图像分析领域有着非常重要的意义。根据视觉的生物学原理,研究人员已提出了针对灰度图像的轮廓检测方法,并取得了较好的检测结果。但是,颜色信息可以表示出图像的大部分信息,在轮廓检测中发挥的作用不可忽视。杨开富等人提出的CO模型可以较好地提取图像中的目标轮廓,但该模型的计算效率还有待提高。文中提出一种轮廓检测模型CRFM(Color-opponent Receptive Field Model),该模型依据视觉信息处理机制,分别模拟视网膜神经节细胞和外侧膝状体细胞感受野的响应。此外,CRFM采用两个不同尺度的高斯偏导函数之差来模拟初级视皮层细胞的颜色双拮抗感受野响应,拟合视觉特征,且由于模拟双拮抗感受野的滤波器通常产生较小的数值,因此加快了其与图像信息卷积的计算速度,降低了运行开销。利用BSDS300数据库的图像进行实验,结果表明,CRFM模型能够获得较好的轮廓检测效果,且具有较CO模型更高的执行效率,具有较好的实用性。     

Guided Image Filtering for Interactive High‐quality Global Illumination

Interactive computation of global illumination is a major challenge in current computer graphics research. Global illumination heavily affects the visual quality of generated images. It is therefore a key attribute for the perception of photo‐realistic images. Path tracing is able to simulate the physical behaviour of light using Monte Carlo techniques. However, the computational burden of this technique prohibits interactive rendering times on standard commodity hardware in high‐quality. Trying to solve the Monte Carlo integration with fewer samples results in characteristic noisy images. Global illumination filtering methods take advantage of the fact that the integral for neighbouring pixels may be very similar. Averaging samples of similar characteristics in screen‐space may approximate the correct integral, but may result in visible outliers. In this paper, we present a novel path tracing pipeline based on an edge‐aware filtering method for the indirect illumination which produces visually more pleasing results without noticeable outliers. The key idea is not to filter the noisy path traced images but to use it as a guidance to filter a second image composed from characteristic scene attributes that do not contain noise by default. We show that our approach better approximates the Monte Carlo integral compared to previous methods. Since the computation is carried out completely in screen‐space it is therefore applicable to fully dynamic scenes, arbitrary lighting and allows for high‐quality path tracing at interactive frame rates on commodity hardware.     

Lightness Recovery for Pictorial Surfaces

An important technique in cultural heritage preservation is multispectral acquisition, where one recovers a detailed spectral record of a painting using carefully calibrated lighting. This is difficult to do with frescoes, because it is hard to recover the spatial variation in light intensity that results from factors like the imaging setup and the curvature of the fresco. We introduce a new formulation of the lightness problem applied to images of pictorial artworks. The problem is different from the conventional lightness problem, because artists often paint the effects of light, so the albedo field contains a component that mimics an illumination field. Our method distinguishes between physical illumination and painted shading through spatial frequency effects and dynamic range considerations. We evaluate our method using multispectral images of paintings, where the physical illumination field is known. Our method produces estimates of the illumination intensity field that compare very well with the known ground truth, and outperforms other state-of-the art lightness recovery algorithms. For frescoes, ground truth is not available, but we show that our method produces consistent results, in the sense that the illumination functions estimated on the image and on (some of) its subimages are very similar on the overlap. We show our method produces qualitatively good color corrections for images of frescoes found on the web.     

基于类比推理的物体明暗描绘方法

通过源图像与目标图像的类比关系，提取源图像中的物体在不同光照条件下生成的图像中的明暗知识，并将其作用于目标图像以完成明暗描绘．在目标图像与源图像上的绘制对象是理想漫反射物体且具有可类比性的情况下，绘制结果是合理的．该方法具有原始数据量小、计算速度快、便于显示效果的控制和交互等特点．     

Virtual Dunhuang Art Cave: A Cave within a CAVE

Virtual Reality can present historical places in a three-dimensional and interactive way, giving visitors a photorealistic impression of objects. Not only existing scenarios can be shown, but VR can also be used to rebuild scenarios that were damaged or destroyed a long time ago, giving new life to the cultural heritage. We used Virtual Reality to present the Mogao Grottos in Dunhuang. This cave site is one of the most important cultural and religious places by the ancient Silk Road. The presentation is to give visitors the impression of visiting the cave site and provide information about the caves, paintings and statues in an interesting way. To achieve this, we developed a new, intuitive interaction paradigm, which enables the user to explore the caves. To give observers a photorealistic impression of the caves and to create a feeling of immersion, innovative rendering techniques were integrated.
The resulting presentation combines Virtual Reality and archaeology to give tourists a realistic experience of this cave site and to support scientists in their research work.     

基于GPU的动态头发渲染

运用模拟头发运动的系统计算头发阴影的阴影生成算法和一个通过每一串头发来模拟光线散射的发射模型,就可以创建出极其真实的头发影像。渲染结果表明,利用以上方法可以渲染出极其逼真的头发。     

Computerised approaches for the detection of diabetic retinopathy using retinal fundus images: a survey

Eye-related disease such as diabetic retinopathy (DR) is a medical ailment in which the retina of the human eye is smashed because of damage to the tiny retinal blood vessels in the retina. Ophthalmologists identify DR based on various features such as the blood vessels, textures and pathologies. With the rapid development of methods of analysis of biomedical images and advanced computing techniques, image processing-based software for the detection of eye disease has been widely used as an important tool by ophthalmologists. In particular, computer vision-based methods are growing rapidly in the field of medical images analysis and are appropriate to advance ophthalmology. These tools depend entirely on visual analysis to identify abnormalities in Retinal Fundus images. During the past two decades, exciting improvement in the development of DR detection computerised systems has been observed. This paper reviews the development of analysing retinal images for the detection of DR in three aspects: automatic algorithms (classification or pixel to pixel methods), detection methods of pathologies from retinal fundus images, and extraction of blood vessels of retinal fundus image algorithms for the detection of DR. The paper presents a detailed explanation of each problem with respect to retinal images. The current techniques that are used to analyse retinal images and DR detection issues are also discussed in detail and recommendations are made for some future directions.     

源自样图的树皮纹理合成技术研究

树皮的真实感表达是树木可视化中的一个重要问题。树皮表面纹理具有丰富的细节,并且树干不同部位的纹理质地可能会发生渐变,要真实模拟树皮纹理的这些效果并不简单。提出一种真实感树皮纹理的合成方法。该方法基于块纹理合成的思想,可以根据几块树皮样图纹理,实现树干部分整张树皮纹理的合成。采用这种合成方法,有效避免了采用一般纹理拼接方法所造成的纹理接缝问题。并且,该方法采用一种控制合成概率的策略有效实现了不同质地的树皮纹理之间的渐变,从而能够真实表现出树皮由老到嫩逐渐变化的效果。基于样本及边缘融合的方式实现了树皮疤痕效果的生成。实验表明,该方法可以有效生成带有生长变化特征的真实感树皮纹理,满足真实感绘制的需求。     

A communication system for distributed computations on a network of personal computers

This paper deals with a software system PCCOM which makes it possible to simulate a distributed memory environment for parallel computations by using a local area network of personal computers. This system consists of FORTRAN subroutines that can be used from application programs. Parallel computations may be performed on a network of personal computers under DOS or any other operating system. This software package simulates, partially, the widespread PVM (Parallel Virtual Machine) package which runs under UNIX. A simple example of an application is given here.     

Collaborative Virtual Simulation Environment for Radiotherapy Treatment Planning

The simulation of Radiotherapy Treatment Planning (RTP) is a normal procedure in oncology clinics carried out on a Simulator machine. The Virtual Simulation of RTP replaces the real Simulator machine with a virtual one by using the CT data sets of a patient instead of the real patient. In this paper, we present a collaborative virtual simulation environment of RTP, named EU-VIRTUOSO, which is based on volume rendering and telecommunication techniques. The RTP procedure is visualised on a virtual patient, which is created by using the CT data of the patient. Different volume rendering and volume interaction techniques, such as DRR, MIP, gradient surface, and iso-surface, supply physicians with high quality rendering images to simulate the real working environment of the Simulator machine. In the collaborative environment, physicians distributed at different locations can work together via network to plan the treatment or to validate the treatment plan on-line by a collaborative application sharing approach. Both concepts virtualised planning and collaborative planning improve the efficiency and accuracy of a radiotherapy treatment while reducing the effort for an individual patient.     

The effects of three blue light filter conditions for smartphones on visual fatigue and visual performance

Although blue light filters have been developed to decrease visual fatigue, the decreased screen brightness and contrast ratios inherent in current filtering techniques should be resolved. To address these issues, we developed a blue light filter, named the Eye Care blue light filter. This study investigated the effects of three blue light filtering techniques (the Eye Care blue light filter, an 80% blue light filter application [app], and a 60% blue light filter app) on visual fatigue and task performance. Thirty‐six healthy adults were recruited. Critical fusion frequency, task performance, and subjective visual fatigue scale were used to assess visual perception and task performance. All subjects played a smartphone game for 40 min in each experimental condition. Task performance was better with the Eye Care blue light filter than with the two filter apps. The value of the Eye Care blue light filter is that it immerses the user in a good task performance environment while reducing blue light exposure per unit of time more than is possible with filter apps.     

Toward the light field display: autostereoscopic rendering via a cluster of projectors

Ultimately, a display device should be capable of reproducing the visual effects observed in reality. In this paper we introduce an autostereoscopic display that uses a scalable array of digital light projectors and a projection screen augmented with microlenses to simulate a light field for a given three-dimensional scene. Physical objects emit or reflect light in all directions to create a light field that can be approximated by the light field display. The display can simultaneously provide many viewers from different viewpoints a stereoscopic effect without head tracking or special viewing glasses. This work focuses on two important technical problems related to the light field display; calibration and rendering. We present a solution to automatically calibrate the light field display using a camera and introduce two efficient algorithms to render the special multi-view images by exploiting their spatial coherence. The effectiveness of our approach is demonstrated with a four-projector prototype that can display dynamic imagery with full parallax.     

Measuring color breakup of stationary images in field‐sequential‐color displays

Abstract— Color breakup is an artifact perceivable on field‐sequential‐color (FSC) displays, both in stationary and in moving images. In this work, a unique device and a method for measuring color breakup on stationary images is proposed. Rotating the field of view of a high‐speed measurement camera in milliseconds simulates saccadic behavior. The target can be a virtual display, a direct‐view display or a projector image. Captured images can be used for quantifying the color breakup of a target display. The results along with an exploration of their application to breakup characterization will be presented.     

A VR-based volumetric medical image segmentation and visualization system with natural human interaction

Virtual Reality - Volume rendering produces informative two-dimensional (2D) images from a 3-dimensional (3D) volume. It highlights the region of interest and facilitates a good comprehension of...