改进SIFT小型无人机视频序列图像自动拼接方法

针对小型无人机视频序列图像视点离散、视角变化有一定运动规律的特点,本文结合Harris特征点和SIFT特征向量的优势,研究实现图像的自动配准;并采用光度对准的方法和加权平均的方法消除光度差异,较好地实现了视频序列图像的无缝拼接。实验证明该方法在图像拼接的准确性、效率等方面较经典的SIFT算法有较大提高。     

A six-camera digital video imaging system sensitive to visible,red edge,near-infrared,and mid-infrared wavelengths

This paper describes a six-camera multispectral digital video imaging system designed for natural resource assessment and shows its potential as a research tool. It has five visible to near-infrared light sensitive cameras, one near-infrared to mid-infrared light sensitive camera, a monitor, a computer with a multichannel digitizing board, a keyboard, a power distributor, an amplifier, and a mouse. Each camera is fitted with a narrowband interference filter, allowing the system to obtain imagery in the blue (447 – 455 nm), green (555 – 565 nm), red (625 – 635 nm), red edge (704 – 716 nm), near-infrared (814–826 nm), and mid-infrared (1631 – 1676 nm) regions of the electromagnetic spectrum. Analogue video acquired by this system is converted to digital format. Radiometric resolution of the imagery is 8-bit (pixel values range 0 – 255). Images obtained by the system can be evaluated individually and/or in combination with each other to assess natural resources.     

THE POSSIBILITY OF LOCAL AUTONOMY

Prevailing theories of local autonomy have largely precluded the possibility for effective local autonomy. Recent alternatives, however, have focused on the law and legal discourse as significant means of sustaining local power. This paper builds on the latter theoretical strain by considering the relation between power and place both within and outside the law. In this paper “autonomy” is reconceptualized with a relational rather than the traditional corporeal theory of power, emphasizing the way in which social objects are reified with power through sets of truth claims. “Local” is reconsidered as one such reification, endowed with a plethora of not merely political, but also cultural and social significations. The result is a more subtle understanding of the way in which power is exercised locally against state domination. This theory is constructed through evidence from a Massachusetts housing policy's drafting and implementation.     

Spatial video and GIS

GIS elemental unit representations of spatial data are often defined in terms of points, lines and areas. However, another type of spatial data that is becoming frequently captured, but as yet is largely ignored in GIS, is that of video. While digital video recording is a commonly encountered medium in modern society and encompasses many forms, from simple personal camcorders through to sophisticated survey and surveillance systems, its geographical representation in a GIS has not been fully examined or realised. In the majority of cases the video footage is usually captured while the device and/or the objects being viewed are in motion. What is of particular interest is when video streams can be, or have been, associated with spatial data such as location and orientation to create geographically referenced videographic data, which, for simplicity, will be defined as spatial video. Fundamentally, the nature of video is to record space, so when spatial properties can be accurately acquired and associated with this footage, an important geographical element can be considered for integration and analysis within a GIS.

Existing spatial video systems, both commercial and research, are predominantly used in survey or LBS roles and are usually bespoke and application specific. These systems do not model spatial video to any recognised standards that is generalised to be both data and platform independent. They do not support GIS integration and/or analysis from a purely spatial content perspective. A video-image/remote-sensing centric approach prevails where usage options range from simple visualisation interfaces to interactive computer vision systems. What has been largely overlooked is a spatial approach where the inherent geographical extent recorded in each video frame can be modelled and used in a geo-spatial analysis context. While this modelling approach has not been fully realised, it does exist in a GIS form based on Open Geospatial Consortium standards, where the spatial context of video is defined in a structure called a ViewCone. However, a ViewCone only defines a 2D model of the geographical extent of each frame and is restricted to a three-or-five sided polygon representation.

Thus, this article examines the potential of modelling spatial video through the use of elemental data types within GIS; gives some examples of using this approach; describes some problems in using spatial video within GIS; and then demonstrates how these problems are being solved. This is done in three stages: Firstly, a detailed overview of spatial video in its current GIS role is provided – this is achieved through a complete introduction to the distinct elements of spatial video followed by a review of its use in both commercial and academic application areas. Secondly, a brief theoretical overview of an alternative GIS-constrained ViewCone data structure is given that defines a more flexible spatial video model for both 2D and 3D GIS analysis and visualisation. Thirdly, a selective sample of results is presented based on an implementation of this approach being applied to a constrained spatial video data source in a specific study area.     

全国地震应急视频会议系统组会模式

介绍点点结构、网状结构和树结构视频会议组会模式技术特点,及在地震应急中存在的问题;结合地震应急视频会议系统发展需求及在不同应用状态(单点连接、多省连接、市县连接、现场连接及应急演练)下的实际应用效果,探讨星形结构和两级树结构在地震应急视频会议中的技术优势,指出现有地震应急视频会议系统平台技术瓶颈及可能解决途径.     

微空间场景与视频分析相结合的审讯室异常行为检测

行为检测是智能视频分析的研究热点。目前,行为分析主要是基于视频图像空间,而丰富的空间场景信息并未得到有效利用。事实上,个体行为与空间场景紧密关联,不同场景可能具有不同的行为表征。本文以审讯室的典型微空间场景为例,以刑讯逼供行为检测为研究内容,探究空间场景约束下的个体异常行为检测方法。首先,从行为变量的概念出发,解析了刑讯逼供的行为变量和行为类型;其次,分析了刑讯逼供行为变量的视频特征,并设计了相应的行为变量检测模型;再次,通过灭点计算实现了空间场景和视频图像的双向映射关系的解算,并在此基础上设计了顾及空间场景的刑讯逼供行为分级分类检测策略;最后,通过模拟实验对本文方法的可行性进行了分析验证。     

高建筑物上闪电普通摄像观测与分析

2009-2010年夏季,在广东省气象局对东南方向的高建筑物上的闪电进行了观测.对获得的普通摄像资料进行了处理和分析,基于对闪电事件引起普通摄像中像素亮度变化的分布特征的分析结果,编写了视频资料处理程序,实现了普通摄像资料中闪电图片的自动提取.在此基础上,统计分析了观测到的广州高建筑物上87次自然闪电的特征,结果表明:这些闪电的持续时间平均为348 ms;对于高度超过500m的建筑物,其上发生闪电的次数明显多于高度低于500 m的建筑物,且闪电的平均持续时间也更长.给出了拍摄到的几幅云下闪电通道呈现蛛状和长距离特征的闪电图片.     

The exceptional activity and growth of the Southeast Crater, Mount Etna (Italy), between 1996 and 2001

Between 1971 and 2001, the Southeast Crater was the most productive of the four summit craters of Mount Etna, with activity that can be compared, on a global scale, to the opening phases of the Pu‘u ‘Ō‘ō-Kūpaianaha eruption of Kīlauea volcano, Hawai‘i. The period of highest eruptive rate was between 1996 and 2001, when near-continuous activity occurred in five phases. These were characterized by a wide range of eruptive styles and intensities from quiet, non-explosive lava emission to brief, violent lava-fountaining episodes. Much of the cone growth occurred during these fountaining episodes, totaling 105 events. Many showed complex dynamics such as different eruptive styles at multiple vents, and resulted in the growth of minor edifices on the flanks of the Southeast Crater cone. Small pyroclastic flows were produced during some of the eruptive episodes, when oblique tephra jets showered the steep flanks of the cone with hot bombs and scoriae. Fluctuations in the eruptive style and eruption rates were controlled by a complex interplay between changes in the conduit geometry (including the growth of a shallow magma reservoir under the Southeast Crater), magma supply rates, and flank instability. During this period, volume calculations were made with the aid of GIS and image analysis of video footage obtained by a monitoring telecamera. Between 1996 and 2001, the bulk volume of the cone increased by ~36×10⁶ m³, giving a total (1971–2001) volume of ~72×10⁶ m³. At the same time, the cone gained ~105 m in height, reaching an elevation of about 3,300 m. The total DRE volume of the 1996–2001 products was ~90×10⁶m³. This mostly comprised lava flows (72×10⁶ m³) erupted at the summit and onto the flanks of the cone. These values indicate that the productivity of the Southeast Crater increased fourfold during 1996–2001 with respect to the previous 25 years, coinciding with a general increase in the eruptive output rates and eruption intensity at Etna. This phase of intense summit activity has been followed, since the summer of 2001, by a period of increased structural instability of the volcano, marked by a series of important flank eruptions.     

CONSTRUCTING,VISUALIZING, AND ANALYZING A DIGITAL FOOTPRINT*

ABSTRACT. Herein, we discuss the desire for new technology, the need for security, and the right to privacy; in doing so, we argue that each of these concerns comprises an important, tripartite debate. To highlight the complexities in this problem, we define our notion of a “digital footprint” and introduce Big Foot—specialized software created for the research described here to facilitate visualization and exploration of the data that comprise Stephen Weaver's personal digital footprint. Using Big Foot we demonstrate how multiple digital personae can be created from the data that constitute one unique digital footprint and provide a methodology for understanding the good and bad impacts that new technologies may have on future societies. One of the primary arguments of this work is that the debate—though not formally recognized—is currently before contemporary society and must receive sufficient attention.     

机载视频影像运动目标检测与跟踪技术

运动目标检测跟踪是一项新兴热点技术,其处理的主要对象是视频影像数据,核心是实现对视频影像数据中运动物体的检测及跟踪。以机载视频数据为研究对象,对这项技术进行了较为深入的分析。将运动目标检测跟踪技术划分为视频影像预处理、目标检测及运动跟踪3个功能部分,并分别分析与之相关的技术方法,阐明该类问题的解决思路和探索方向。