Synergistic effects of combined Landsat-TM and SIR-B data for forest resources assessment

Abstract

Three different incidence angle data sets, obtained by the Shuttle Imaging Radar-B in October 1984 over a forested area in northern Florida, were combined with Landsat-5 Thematic Mapper data, to create a digitally registered 10 channel optical/microwave data set. The work discussed in this paper involved the analysis of the data obtained by the two sensors separately and in combination, to determine if there are synergistic effects obtained through the simultaneous use of data obtained from both the optical and microwave portion of the spectrum. The radar data were filtered with a low-pass filter to eliminate the speckle noise. Classifications of the TM, SIR-B and combined TM +SIR-B data sets were performed with both per-point and contextual classifiers. The results showed that filtered radar data can be used to classify accurately major cover types (i.e., pine forest, swamplands and radar smooth targets) and that the contextual classifier provided better classification performance. The combined TM and SIR-B data provided statistically improved classification performances compared to classifications from the three incidence angle SIR-B data, or the TM data alone. A four band subset (TM-2, TM-4, TM-5, and SIR-B 28°) of the 10 channels of the combined TM and SIR-B data set provided higher classification performances (91 per cent overall performance) than the 10 channel data set (86 per cent overall performance).     

Radar observations of basaltic lava flows,Craters of the Moon,Idaho

Abstract

Radar images were assessed to determine the backscatter characteristics of basaltic lava flows of predominantly pahoehoe textures and the ability to detect fissure vents. The images were obtained from synthetic aperture side-looking airborne radar systems—X-band HH, X-band HV, L-band HH and L-band H V. Smooth, collapsed blisters of shelly pahoehoe have weak returns in all four radar images. These returns are identical to those from pahoehoe surfaces covered with smooth mantles of windblown sediments. Hummocky pahoehoe flows have strong backscatter in all four images, most likely due to the large range in surface roughness causing multiple scattering at both radar wavelengths. Aa lava flows show the greatest variation in backscatter intensities—strong XHH, weak XHV, strong LHH and very strong LHV returns. This variation is due to an increase in multiple scattering at the L-band scale. Although smooth and rough surface textures can be differentiated in the radar images, there are constraints in tracing textural changes back to a particular fissure vent, in part because near-vent flows do not have unique radar signatures. Eruptive fissures are detectable in the radar images by virtue of associated parallel spatter ramparts which have diagnostic, strong backscatter in the X-band images that are in contrast to the weak backscatter of the surrounding shelly pahoehoe lava. However, spatter ramparts are not delineated in the L-band images. The centimetre-scale relief of the agglutinate spatter may cause scattering of the X-band energy more than the L-band energy. Although the structures are several metres high, the look directions for both imaging systems are approximately parallel to the trend of the ramparts. The rampart walls do not serve as reflectors. Such findings emphasize the importance of look direction in the use of radar images to characterize terrains.     

Application of the semivariogram textural classifier (STC) for vegetation discrimination using SIR-B data of Borneo

Abstract

Classification of Shuttle Imaging Radar-B (SIR-B) data from a rainforest-covered portion of Borneo is performed using image texture. The algorithm used is the semivariogram textural classifier (STC). This is a deterministic, supervised parallelepiped type classifier which provides the option of combining textural and radiometric information. Textural information is expressed by the semivariogram function. Radiometric information is conveyed by the mean digital number (DN) value. Results of the classificaiion cmulale a previously published map obtained by visual interpretation of the same SIR-B data set.     

雷达接收机多通道高速数据采集系统

介绍了一种用于雷达接收机的多通道高速数据采集系统。该系统以计算机为采集主控单元,兼容多种格式的数据,可以实现多通道的循环采集。系统采集单元由可编程逻辑器件实现,简化了电路结构,增强了系统设计的灵活性和可靠性,降低了体积与成本。实测结果表明该系统工作稳定、性能良好,目前已应用于多个型号的雷达接收机中。     

Simulation of L-band and HH microwave backscattering from coniferous forest stands A comparison with SIR-B data

Abstract

Shuttle Imaging Radar-B (SIR-B) images of coniferous forest stands dominated by Ponderosa pine in the Mt. Shasta region of northern California were used to evaluate a composite L-band HH backscattering model of coniferous forest stands. Eight forest stands were employed to describe the relative trend and distribution of backscattering coefficients. It was found that (1) both SIR-B and simulated backscattering coefficients for the eight stands have similar trends and relations to average tree height and average number of trees per pixel and (2) the dispersion and distribution of simulated backscattering coefficients from each stand broadly matched SIR-B data from the same stand. Although it is difficult to draw any strong conclusions from the comparisons because the experimental data arc limited in both quantity and quality and are also undersampled, the comparisons indicate that a stand-based L-band HH composite model seems promising for explaining backscattering features. The means of the backscattering coefficients are determined by the average tree height and average number of trees per pixel in the stands. The distributions of the backscattering coefficients are modelled through random assignment of tree numbers, heights and spatial distribution within a pixel.     

Adaptive rerouting of data flows in distributed data Centers

In present computer structures in view of distributed data centers (DC) provides flexible management of network topology and functions in real time. This method allows to get rid of the excess costs of expensive equipment and network service. To provide resiliency of network infrastructure of DC it is necessary to use effective fast rerouting algorithms. In this work we propose adaptive rerouting algorithm of data flows in distributed DC based on the paired shifts data.     

基于气象雷达回波3D重建的Marching Cubes改进算法

根据气象雷达回波数据的三维极坐标分布特点,提出一种改进的Marching Cubes三维重建算法.该算法将Marching Cubes常规算法中的单位正立方体构建转换为直接对回波极坐标数据的拟柱体构建,生成相应的等值三角面,并对三角面的顶点数据进行地曲订正,供OpenGL显示.为进一步提高重建算法的效率,该算法避免了对高仰角远距离无回波区的重建.实验表明,该算法有效实现了雷达回波的三维重建.     

Simulation of radar with a knife-like antenna beam using precipitation radar data

The concept of radar using a knife-like antenna beam is discussed and compared with precipitation radar (PR). An example of PR data processing is given. Two approaches are used to retrieve variance of slope: point-to-point algorithms and a linear angular algorithm. The algorithm for the PR data transformation into data of radar with a knife-like antenna beam has been developed. Transformation of real satellite data into data of radar with a knife-like antenna beam enables one for the first time to simulate measurements of future space radar qualitatively. Transformed data are used to validate the retrieval algorithms developed for radar with a knife-like antenna beam. Numerical simulation is also used to test the retrieval algorithms. The noise effect on the precision of slope variance retrieval for the PR and radar with a knife-like antenna beam is considered. Data processing confirms that the precision of radar with a knife-like antenna beam is significantly higher than the precision of PR. Numerical simulation is also used to explore the possibility of sea-surface slope imaging. The obtained results confirm that only radar with a knife-like antenna beam can be employed to retrieve real images of the processes occurring on sea-surface slopes.     

雷达多目标方位测量数据的一种处理方法

多目标数据关联是雷达数据融合过程中的重要一环。针对分布式雷达组网模式 ,在目标批数未知的条件下 ,提出了一种杂波环境下的多目标点迹关联算法。该算法利用雷达对目标的方位测量数据 ,通过引入关联矩阵 ,建立多目标多雷达数据关联数学模型 ,采用模拟退火技术 ,在使似然函数最大化的意义下求取关联矩阵和监视空域中目标的批数。根据多个雷达的多个采样周期的关联矩阵 ,建立各雷达测量数据之间的相关关系 ,为目标跟踪和数据融合提供前提条件。模拟仿真结果表明了算法的有效性。     

Estimating friction errors in MOC analyses of unsteady pipe flows

Errors arising from the numerical treatment of friction in unsteady flows in small pipe networks are assessed for fixed-grid, method of characteristics analyses (MOC) with no interpolation. Although the results of the study are targeted at general unsteady flows, the underpinning analytical development is based on the behaviour of standing waves. This enables quantitative conclusions to be drawn about the sensitivity of MOC solutions to frequency. The development is undertaken first for a single pipe and then for networks, with and without a loop. The performance of MOC solutions is modelled with the aid of polynomial transfer matrices that are analogous to transfer function matrices available directly from partial differential equations of water hammer. It is found that, in a single pipe, the numerical errors tend to increase damping at all frequencies, but that, in networks, either increased or decreased damping may occur. The errors place both higher and lower limits on the frequencies that can propagate along a pipe in a numerical analysis. This contrasts with the physical case where only a lower limit exists. The work presented is part of a wider project with the long-term aim of automating the selection of numerical grid sizes in MOC analyses of unsteady flows.     

雷达状态监测系统数据传输技术的实现

雷达状态监测与诊断系统必须具有对雷达进行数据采集与特征提取、实时监测、功能检查、故障显示及故障隔离等功能,而各功能的协同合作,监测点与主控机间的信息交换均需经数据传输这一重要环节,针对此提出一种在功能模块内部采用较为成熟便捷的USB方式,而在主机与各从机之间采用无线传输方式的解决方案,进一步解决了雷达监测与诊断系统中数据吞吐量大、冗余空间小、电路改造复杂等问题,并提高了系统的可靠性及可扩展性,增强了动态环境的适应性。     

数据流上最近频繁项集挖掘算法

数据流频繁项集挖掘是指在数据流中找出出现频数大于给定的最小支持度的项集过程。随着一些新兴应用如传感器网络、网络监控等的出现,数据流中频繁项集挖掘引起了很大的重视。提出了一种新颖的数据流频繁项集挖掘算法RFIF。不同于现有算法,RFIF算法针对现实中的一些实际应用,更多的考虑最近时间发生的事件,但也不完全抛弃历史数据,通过引入GIMT函数,逐渐加大项集支持度的阈值,减少对历史数据中频繁项集的维护。实验验证了算法的有效性。     

Forward Observer system for radar data workflows: Big data management in the field

There are unique challenges in managing data collection and management from instruments in the field in general. These issues become extreme when “in the field” means “in a plane over the Antarctic”. In this paper we present the design and function of the Forward Observer a computer cluster and data analysis system that flies in a plane in the Arctic and Antarctic to collect, analyze in real time, and store Synthetic Aperture Radar (SAR) data. SAR is used to analyze the thickness and structure of polar ice sheets. We also discuss the processing of data once it is returned to the continental US and made available via data grids. The needs for in-flight data analysis and storage in the Antarctic and Arctic are highly unusual, and we have developed a novel system to meet those needs.We describe the constraints and requirements that led to the creation of this system and the general functionality which it applies to any instrument. We discuss the main means for handling replication and creating checksum information to ensure that data collected in polar regions are returned safely to mainland US for analysis. So far, not a single byte of data collected in the field has failed to make it home to the US for analysis (although many particular data storage devices have failed or been damaged due to the challenges of the extreme environments in which this system is used).While the Forward Observer system is developed for the extreme situation of data management in the field in the Antarctic, the technology and solutions we have developed are applicable and potentially usable in many situations where researchers wish to do real time data management in the field in areas that are constrained in terms of electrical supply.     

雷达状态监测系统数据传输技术的实现

雷达状态监测与诊断系统必须具有对雷达进行数据采集与特征提取、实时监测、功能检查、故障显示及故障隔离等功能,而各功能的协同合作,监测点与主控机间的信息交换均需经数据传输这一重要环节,针对此提出一种在功能模块内部采用较为成熟便捷的USB方式,而在主机与各从机之间采用无线传输方式的解决方案,进一步解决了雷达监测与诊断系统中数据吞吐量大、冗余空间小、电路改造复杂等问题,并提高了系统的可靠性及可扩展性,增强了动态环境的适应性.     

扫描昆虫雷达数据分析系统的设计和研究

利用自行设计,制作的扫描昆虫雷达数据分析系统,对雷达数据进行图像绘制,通过参数设置统计指定空间范围内昆虫回波点的方位、高度、距离、密度等关键生物学参数,以实现昆虫活动的准确预测和预报.通过利用R统计平台与生物学辅助方法相结合开发建立分析平台.系统在实现雷达数据读取、信号格式转换、回波数据统计等功能的同时,在技术上实现了对重建迁飞害虫空间飞行动态的支持,将填补原有程序中没有数据分析功能的空白.     

The use of optic and radar satellite data for coastal environments

The pressure of population and its demands for fuel, for heating or industrial usage, causes destruction of the natural environment. One of the clearest examples for the accelerated degradation of changes in the forest area and coastline is in the Kilyos–Karaburun coastline located in the northern part of Istanbul metropolitan city. The open‐pit mining activities in the region are threatening the balances of both sea and land ecosystems, and cause degradation of forest areas and changes along the coastline. In this paper, the changes are examined with multisensor satellite data such as Landsat Thematic Mapper (TM), SPOT Panchromatic (P), and RADARSAT images by using different image‐processing techniques. The degrees of changes in coastline length and coastal region area were calculated, and the effectiveness of the use of different image data sets was outlined for coastal environments.     

SOFA: An extensible logical optimizer for UDF-heavy data flows

Recent years have seen an increased interest in large-scale analytical data flows on non-relational data. These data flows are compiled into execution graphs scheduled on large compute clusters. In many novel application areas the predominant building blocks of such data flows are user-defined predicates or functions (Udfs). However, the heavy use of Udfs is not well taken into account for data flow optimization in current systems.Sofa is a novel and extensible optimizer for Udf-heavy data flows. It builds on a concise set of properties for describing the semantics of Map/Reduce-style Udfs and a small set of rewrite rules, which use these properties to find a much larger number of semantically equivalent plan rewrites than possible with traditional techniques. A salient feature of our approach is extensibility: we arrange user-defined operators and their properties into a subsumption hierarchy, which considerably eases integration and optimization of new operators. We evaluate Sofa on a selection of Udf-heavy data flows from different domains and compare its performance to three other algorithms for data flow optimization. Our experiments reveal that Sofa finds efficient plans, outperforming the best plans found by its competitors by a factor of up to six.