利用低空视频检测道路车辆

针对背景像素的移动,提出了SURF特征稳像和光流法向量相结合的新方法来解决低空视频的道路车辆检测。首先,检测两帧图像的SURF特征;再用最近邻匹配得到两幅图像的匹配点对;随后结合RANSAC和最小二乘法计算全局运动参数向量,获得稳定的帧;最后,根据稳定的帧计算光流法向量,并检测出运动车辆。实验结果表明,基于SURF算子的图像稳像算法在不损失稳像精度的前提下,能够提高图像稳像算法的速度,所提方法能够有效地检测出运动车辆。     

基于隐含语义相关性分析的视频语义检索

提出了隐含语义相关性分析的处理方法,对描述视频内容结构的视频文档矩阵进行奇异值分解和变换,可得到表达可视特征与语义间隐含相关性的关系矩阵,用于视频检索。分析和实验表明,所提出的方法能保留视频内容结构中核心的语义元素,消除冗余的相关性干扰,还能够通过矩阵降维减少计算量,改善视频语义内容检索的效果。     

无人艇载雷达视频无线传输技术研究

雷达视频数据量大,更新频率高,传输带宽占用量大.无人艇（USV）岸艇数据传输带宽有限,传输信息种类多、数量大.在无人艇使用过程中,雷达视频是岸基操作人员安全航行保障、交战对象搜索确认等不可或缺的支持信息,然而岸艇数据互通带宽资源的紧缺和雷达视频的大信息传输需求之间的矛盾必然存在.本文根据雷达探测成像原理,对雷达视频进行数字化表示,经压缩、数据传输和复原显示,实现无人艇岸基控制站对艇载雷达视频的还原显示.该技术在某型USV控制系统中的应用结果表明：视频压缩比高、处理时延低、视频还原完整、容错性好.     

Diffuse emission of CO2 from the Fossa crater,Vulcano Island (Italy)

 Numerous measurements of CO₂ degassing from the soil, carried out with the accumulation chamber method, indicate that in the period April–July 1995 the upper part of the Fossa cone released a total output of 200 t d^–1 of CO₂, which corresponds to approximately 1000 t d^–1 of steam. These large amounts of fluids are of the same order of magnitude as those released by the high temperature fumarolic field located inside the crater. The spatial distribution of soil gas fluxes shows that the main structures releasing CO₂ are the inner slopes of the crater and a NW–SE line, located NE of the crater rim, which correspond to the main direction of Vulcano Island active faults. The comparison of the φCO₂ maps with the soil temperature distribution, derived from both direct measurements and airborne infrared images, indicates the occurrence of extensive condensation of fumarolic steam within the upper part of the Fossa cone, whose total amount is comparable to the rainfall budget. Part of the condensate which originates from this process contributes to the recharge of the phreatic aquifer of Porto Plain, modifying the chemical and isotopic composition of the groundwater. Received: 1 September 1995 / Accepted: 8 January 1996     

移动视频通信快速块匹配算法分析

先提出移动视频通信对运动估计搜索算法在运算时间和准确度上的要求.在对目前运动估计快速块匹配算法研究的基础上,简述了运动估计的原理;揭示了在视频质量、搜索速度和压缩码率等方面提高算法效率的3类主要问题：初始搜索点的选择、匹配准则和搜索策略;分别阐述了目前常用的解决这3类问题的方法和相应算法,并进行了比较和分析;提出运动估计算法的发展趋势.     

H.26L参考帧选择技术研究与实现

采用了预测编码的视频数据对传输差错极为敏感,为了有效地消除网络传输错误对解码图像的影响,介绍了一种基于反馈的参考帧选择(RPS:Reference Picture Selection)技术.它利用反馈信道传回的差错信息,选择被正确解码的帧作为参考来进行编码.仿真试验给出了各种RPS模式下图像的主客观质量,结果表明该方法对抑制传输差错的扩散与差错恢复具有很好的效果.     

基于H．264编码标准的远程视频采集系统的设计与实现

通过对如何构建远程视频采集（监控）系统的关键技术进行了较深入的研究，解决了非宽带环境下视频数据连续性和视频数据丢包等问题，视频编解码使用H．264压缩卡完成。     

顾及视频地理映射的人群密度估计方法

针对复杂场景下人群计数及地图可视化问题,提出了一种顾及视频地理映射的人群密度估计方法。首先,通过迁移学习的方式,构建了适合于复杂场景的人群语义分割模型;将视频与GIS相结合,求解摄像机和人群场景的单应矩阵;基于人群语义分割结果及单应矩阵,可将人群多边形映射至二维地图。然后,设计等距分区和格网分区2种分区方案;根据人群语义分割结果,统计不同分区方案下各子区人群密度。最后,基于训练的各子区人群密度值,计算视域内人口总数;通过人群目标点符号均匀填充人群多边形,进行地图可视化。实验结果表明：① 本文构建的人群语义分割模型,可实现大场景下人群的高精度分割,精度为94.11%;② 将视频与GIS相结合,实现了人群的地图映射和地图可视化表达,达到了人群可定位、可量测和可空间分析的目标;③ 实现了监控视频人群的精准计数,将视域划分更多子区有利于提高计数精度。与基于密度图的人群密度估计方法相比,本文方法在高空、高密集度的大场景中具有优势,能有效解决人群难以精准计数及地图可视化的问题,可用于大型活动、车站、商场、运动场馆的人群监管。     

Video monitoring of in-channel wood: From flux characterization and prediction to recommendations to equip stations

Wood flux (piece number per time interval) is a key parameter for understanding wood budgeting, determining the controlling factors, and managing flood risk in a river basin. Quantitative wood flux data is critically needed to improve the understanding of wood dynamics and estimate wood discharge in rivers. In this study, the streamside videography technique was applied to detect wood passage and measure instantaneous rates of wood transport. The goal was to better understand how wood flux responds to flood and wind events and then predict wood flux. In total, one exceptional wind and seven flood events were monitored on the Ain River, France, and around 24,000 wood pieces were detected visually. It is confirmed that, in general, there is a threshold of wood motion in the river equal to 60% of bankfull discharge. However, in a flood following a windy day, no obvious threshold for wood motion was observed, which confirms that wind is important for the preparation of wood for transport between floods. In two multi-peak floods, around two-thirds of the total amount of wood was delivered on the first peak, which confirms the importance of the time between floods for predicting wood fluxes. Moreover, we found an empirical relation between wood frequency and wood discharge, which is used to estimate the total wood amount produced by each of the floods. The data set is then used to develop a random forest regression model to predict wood frequency as a function of three input variables that are derived from the flow hydrograph. The model calculates the total wood volume either during day or night based on the video monitoring technique for the first time, which expands its utility for wood budgeting in a watershed. A one-to-one link is then established between the fraction of detected pieces of wood and the dimensionless parameter “passing time × frame rate ”, which provides a general guideline for the design of monitoring stations.     

Observations and conceptual modelling of morphological coupling in a double sandbar system

Nearshore sandbars, located in <10 m water depth, can contain remarkably periodic alongshore undulations in both cross‐shore position and depth. In a double sandbar system, the alongshore spacing of these morphological patterns in the inner sandbar may be identical to those in the outer sandbar. Although this morphological coupling has been observed previously, its frequency and predominance remain unclear. In this paper, we use a 9.3‐year dataset of daily low‐tide time exposure images from the double‐barred beach at Surfers Paradise (Gold Coast, Australia) to analyse the temporal and spatial characteristics of morphological coupling within a double sandbar system. We distinguish five types of morphological coupling between the inner and outer sandbars, of which four coincide with a downstate progression of the outer bar. Coupling is either in‐phase (with a landward perturbation of the inner bar facing an outer‐bar horn) or out‐of‐phase (with a seaward perturbation of the inner bar facing an outer‐bar horn), where the coupled inner‐bar features either consist of rip channels or, predominantly, perturbations of the low‐tide terrace. Cross‐correlation of the image‐derived inner‐ and outer‐bar patterns shows coupling to be a common phenomenon in the double sandbar system studied here, with coupling in 40% of the observations. In contrast to previous observations of sandbar–shoreline coupling at single‐barred beaches, in‐phase coupling (85% of all coupled bar patterns) predominates over out‐of‐phase coupling (15%). Based on our observations and bathymetries assimilated from the images for a restricted set of coupling events, we hypothesize that the angle of offshore wave incidence, wave height and depth variations along the outer sandbar determine the type of flow pattern (cell circulations versus meandering currents) above the inner bar and hence steer the type of coupling. Copyright © 2012 John Wiley & Sons, Ltd.