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。     

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.     

监控视频动态目标的空间定位方法北大核心CSCD

针对监控视频动态目标的空间定位问题,本文在考虑相机畸变的前提下,对监控相机、目标像素坐标和地理场景之间的映射关系进行了研究,提出了基于数字表面模型(DSM)和基于平面约束的目标定位算法。首先,完成相机的标定,确定相机的成像模型;然后,提取畸变校正后的目标像素坐标,并通过目标定位算法计算目标的三维地理坐标;最后,进行了定位精度评定,并分析了两种定位算法的应用特点。本文的定位算法将以像素坐标定位的目标数据解析为以三维坐标定位的空间地理信息,为多摄像头的目标跟踪提供了统一的地理参考框架。     

广西天气视频会商系统平台建设的探讨

为了提高预报准确率,加强广西各级气象部门的沟通,更好的为社会提供气象服务,通过探讨广西天气视频会商系统现状、不足、发展需求,提出更优化的广西“区—市—县”三级网络高清视频会商系统的设计、建设方案,以期加快气象现代化建设步伐,提高全区气象预报水平和防灾减灾决策服务应急防御能力.     

近地面农情视频定位系统实现

农情监测是现代农业信息化中的核心内容。本文提出了近地面农情的视频监控系统方案,通过建立固定云台和移动云台视频系统,结合GIS和GPS软硬件平台,研发视频空间定位关键技术,实现了基于GIS和GPS的近地面农情视频监控系统的连续监测。近地面农情视频定位系统综合反映实时、准确、精细的农情,便于精准农业变量决策和作业。     

一种无人机视频帧自动拼接方法

无人机视频帧具有低对比度和色彩可读性差等缺点,为了解决这些问题并从视频中自动获取视频帧,本文提出一种无人机视频帧自动拼接方法。首先介绍相位相关理论,并推导出指定重叠度视频帧提取公式,在此基础上进行指定重叠度视频帧的自动提取;最后利用改进的SURF算法完成视频帧的匹配和拼接。实验结果表明本文采用的方法能实现视频帧的自动提取和快速拼接。     

Rapid texture mapping from image sequences for building geometry model

An effective approach, mapping the texture for building model based on the digital photogrammetric theory, is proposed. The easily-acquired image sequences from digital video camera on helicopter are used as texture resource, and the correspondence between the space edge in building geometry model and its line feature in image sequences is determined semiautomatically. The experimental results in production of three-dimensional data for car navigation show us an attractive future both in efficiency and effect.