利用ADS40相机快速生成正射影像图的方法研究

介绍了ADS40相机快速生成正射影像图的方法,即利用高精度POS设备能直接定向测图的特点,省去空三T序,利用POS解算出的外方位元素和自动提取的DEM进行正射影像纠正,结合实际生产项目对成图精度进行了分析。试验结果表明,ADS40相机应用于航测生产可大幅度缩短成图周期,利用本文的生产方法可以满足正射影像图精度要求,并节省大量时问,适用于应急测绘保障。     

1989 Exclusive economic zone symposium: Summary and recommendations

Abstract

The fourth in a series of biennial national Exclusive Economic Zone symposia was held on November 14–16, 1989. The purpose of the meeting was to examine ongoing and planned mapping and research activities in the ocean waters of the United States. Approximately 220 individuals attended the meeting. Issues discussed related to digital seafloor mapping projects, cooperative federal‐state programs, and requirements for additional data and information. Symposium recommendations included the need for increased surveying in coastal waters, development of standards for digital data dissemination, increased coordination with coastal states and federal agencies, and additional geophysical measurement systems abroad all mapping ships.     

数字海图三维可视化应用技术研究

结合目前数字海图的三维可视化应用需求,对不同类型的数字海图从数据获取、处理、三维表达、可视化管理和应用等方面进行了分析。主要介绍了栅格海图的可视化显示,shp矢量海图图层的自动加载和三维符号化显示,基于海图控件的S-57的SENC海图的动态、多要素海图信息影像化三维表达和管理等方面的内容,为海洋测绘成果应用、测绘信息保障提供新的技术手段和应用平台。     

Digital signal processing for precision wide-swath bathymetry

A mathematical model is formulated which accurately represents the envelope function of bottom return signals received from a number of spatial directions comprising a wide swath. The bottom return signals are processed utilizing a digital nonrecursive matched filter whose coefficients are tapered using a Tukey window. High-speed convolution employing the fast Fourier transform is examined for implementation of the digital matched filtering operation. Computer simulation of the signal processing system indicates that, even in the presence of considerable background and fluctuation noises, the processor provides an output signal having a well-defined peak. The error in time of arrival is found to be less than 3 ms, corresponding to an error in depth of less than 0.1 percent, for an average signal-to-noise ratio of 15 dB and a vertical ocean depth of 12 000 ft (3.7 km). These performance figures apply to the most difficult case of mapping at angles ofpm 45degoff vertical.     

临时验潮站深度基准面确定技术的改进

在临时验潮站深度基准面的传递推估中加入时间性的要求,再将潮差比法确定的深度基准面经同步改正,有效地提高了深度基准面的传递精度,并给出了评定其精度的可行方法。     

模板化数字地图编绘技术的研究与应用

通过研究基于模板的数字地图编绘技术,建立了各类数据处理模型,将制图者的编绘经验融入到模板中,从技术上保证了数字地图编绘的实用性,满足了地理信息获取和地图制图出版的双重要求,实现了数字地图和纸质地图的一体化生产。     

基于经纬仪的数字化测图实习教学尝试

针对一些高校电子全站仪较少的状况,提出了利用经纬仪进行数字化测图教学实习的思想,在实践的基础上摸索出了用经纬仪进行数字化测图教学实习的成功经验,给出了具体的作业方法。     

无人机的海岸地形航测技术探讨

根据海岸带的定义,说明其地形图测绘的内容及要求。分析了无人机航测系统中数码相机的检校内容,参照航空摄影测量规范和无人机航测外业实践,探讨了无人机进行海岸带地形测量的方法和步骤,对海岸带区域开展无人机航测作业具有一定的参考意义。     

A distributed microprocessor architecture for fixed and mobile acoustic array adaptive beam forming

This paper presents a state-of-the-art approach to an important sonar signal-processing problem, A theoretical foundation for source oriented beam forming (SOBF) is presented. A distributed processing element is introduced, discussed, and offered as one solution to the at-sea platform implementation of high-powered digital signal processing such as SOBF. While many of the details of the implementation are beyond the scope or intent of this paper, they may be found in the references (those references not in the open literature are obtainable from the authors).     

3D空间航片纹理源的纹理映射问题

随着数字三维城市建设的快速推进,传统的纹理获取方法已不能满足快速建模的要求。提出了一种基于航片纹理源的3D空间纹理映射方法,基于摄影测量学相关理论,通过设计算法,实现了建筑物侧面纹理的自动匹配。实验证明,这种方法简单、高效,适用于大面积建筑物3D建模。     

Spatial diversity equalization applied to underwater communications

Underwater acoustic digital communication is difficult because of the nature of the fading multipath channels. Digital signal processing, such as adaptive equalization, is known to greatly improve the communication data rate by limiting intersymbol interference (ISI). However, existing underwater acoustic equalization studies are limited to single-channel techniques, and spatial diversity processing is limited to selection or combining. In this paper, we design minimum mean-square error (MMSE) equalizers jointly among all spatial diversity channels. We call this spatial diversity equalization (SDE). Results are based on a very sparse vertical array in a midrange underwater acoustic channel. We study the effect of element number and placement, the length of the equalization filters, and linear feedforward versus nonlinear decision feedback algorithms. A suboptimum equalizer combiner (EC) is studied to alleviate the computational intensity of JCE. We first design the system for a known acoustic channel; later, some results are verified using adaptive algorithms. Results are presented both in terms of the mean-square error (MSE) and the probability of a symbol error. The latter is important as it is the ultimate interest for a digital communication system. We found that system performance improves rapidly with an increase in the number of spatial channels     

Stereovision imaging on submersible platforms for 3-D mapping of benthic habitats and sea-floor structures

We investigate the deployment of a submersible platform with stereovision imaging capability for three-dimensional (3D) mapping of benthic habitats and other sea-floor structures over local areas. A complete framework is studied, comprising: 1) suitable trajectories to be executed for data collection; 2) data processing for positioning and trajectory followed by online frame-to-frame and frame-to-mosaic registration of images, as well as recursive global realignment of positions along the path; and 3) 3D mapping by the fusion of various visual cues, including motion and stereo within a Kalman filter. The computational requirements of the system are evaluated, formalizing how processing may be achieved in real time. The proposed scenario is simulated for testing with known ground truth to assess the system performance, to quantify various errors, and to identify how performance may be improved. Experiments with underwater images are also presented to verify the performance of various components and the overall scheme.     

数字测图中的坐标变换方法

针对数字地图的特点,探讨数字测图中的坐标变换方法,总结了一套作业思路和方法,使外业测图不需提前单独进行控制测量,且设站灵活,内业能够充分利用各种满足精度要求的测量数据和数字图进行数字化成图。配以少量控制点,该模式也可在大面积数字测图中使用。从而可减少外业工作量,显著提高工效。     

User expectations for multibeam echo sounders backscatter strength data-looking back into the future

With the ability of multibeam echo sounders (MBES) to measure backscatter strength (BS) as a function of true angle of insonification across the seafloor, came a new recognition of the potential of backscatter measurements to remotely characterize the properties of the seafloor. Advances in transducer design, digital electronics, signal processing capabilities, navigation, and graphic display devices, have improved the resolution and particularly the dynamic range available to sonar and processing software manufacturers. Alongside these improvements the expectations of what the data can deliver has also grown. In this paper, we identify these user-expectations and explore how MBES backscatter is utilized by different communities involved in marine seabed research at present, and the aspirations that these communities have for the data in the future. The results presented here are based on a user survey conducted by the GeoHab (Marine Geological and Biological Habitat Mapping) association. This paper summarises the different processing procedures employed to extract useful information from MBES backscatter data and the various intentions for which the user community collect the data. We show how a range of backscatter output products are generated from the different processing procedures, and how these results are taken up by different scientific disciplines, and also identify common constraints in handling MBES BS data. Finally, we outline our expectations for the future of this unique and important data source for seafloor mapping and characterisation.     

Fifth generation digital sonar signal processing

This paper discusses the evolutionary development, which has taken place over the last decade, in digital sonar systems architecture with the application of first, second, and third generation computers as system controllers for sonar systems. It is the opinion of the authors that, with the arrival of microprocessors, the system controller tasks in real time digital sonars will diminish. We present, as the "fourth generation," the present systems which still have a relatively large CPU, assisted by an array of microprocessors under their control for several subtasks which can be handled, more efficiently, locally in the systems. The "fifth generation" concept is postulated as a further development of this concept. A distributed processing scheme is presented in which the processing elements are actually highly functionally distributed themselves at the lowest level of architecture; consequently, the user views them as uniprocessors within the tightly coupled network. This approach should result in relatively high throughput utilizing a fairly small repertoire of modular hardware components and requiring minimal software effort by implementing, via firmware, very high level macros. This concept allows adaptive system architecture for the various advanced sonar data processing requirements for multielement linear, spatial, or blanket type array systems postulated for the future.     

一种基于GPU和内存映射文件的高分辨率遥感图像快速处理方法

高分辨率遥感图像处理经常面临程序执行时间过长和内存空间不足的问题,虽然并行计算技术可以提高遥感图像的处理速度,但是无法降低算法占用的巨大内存空间。为了解决这一问题,本文提出了一种利用CUDA和内存映射文件的高分辨率遥感图像快速处理方法,并以K-Means算法为例进行了实现。其中,CUDA技术可以有效利用GPU强大的并行计算能力,而内存映射文件技术降低了磁盘I/O速度较慢对算法性能的影响。实验结果表明,本文方法比传统K-Means聚类算法计算速度提高了30倍左右,内存使用量降低了90%以上。     

海岸地形无人机测绘系统选型分析

根据海洋测绘的技术要求和特点,论述无人机测绘技术的发展及其性能指标,分析无人机航摄作业的主要难点和要求,提出海岸地形无人机测绘系统选型条件,并针对国内典型的无人机测绘系统进行选型分析,得出明确结论,为海洋测绘无人机测绘系统建设提供支撑。     

利用高程基准模型实时获取海拔高技术研究

高程信息是时空位置的重要组成部分,实时获取高精度海拔高是测绘导航信息化的关键步骤之一。北斗导航终端能快速高效地测定大地高,结合高精度的数字高程基准模型,可实时获取精密海拔高程。在顾及1985国家高程基准与全球高程基准之间垂直偏差的基础上,基于GOCE+EGM08重力场模型构建了统一到CGCS 2000椭球的区域数字高程基准模型,该模型范围对应北斗区域导航的覆盖范围,即55°S~55°N,55°E~180°E,模型精度优于米级,满足北斗导航终端对海拔高的应用需求;利用实时SQLITE数据库技术,基于该数字高程基准模型构建了北斗导航终端的海拔实时获取系统,实现了任意测点精密海拔高程的实时获取。     

基于对数比转换方法的沉积物粒级组分空间预测与底质类型制图

以废黄河三角洲表层粒度分析数据为基础,探讨了对数比转换和kriging插值相结合方法在沉积物粒级组分空间预测和底质类型制图中的应用。结果表明,基于沉积物粒级组分原始数据的kriging预测方法难以保证各组分预测结果的非负和定和要求,因而预测结果的可信度低;而对数比转换kriging方法不但满足非负和定和要求,而且还有着更优的组分预测结果和较高的底质类型制图精度。新方法对于开展定量化的沉积物粒级组分预测和底质类型制图具有参考价值。     

Target Classification and Remote Sensing of Ocean Current Shear Using a Dual-Use Multifrequency HF Radar

In this paper, we describe a high-frequency (HF) radar capable of multifrequency operation over the HF band for dual-use application to ship classification and mapping ocean current shear and vector winds. The radar is based on a digital transceiver peripheral component interconnect (PCI) card family that supports antenna arrays of four to 32 elements with a single computer, with larger arrays possible using multiple computers and receiver cards. The radar makes use of broadband loop antennas for receive elements, and a number of different possibilities for transmit antennas, depending on the operating bandwidth desired. An option exists in the choice of monostatic or multistatic operation, the latter providing the ability to use several transmit sites, with all radar echo signal reception and processing conducted at a single master receiver site. As applications for such a multifrequency radar capability, we show measurement and modeling examples of multiple frequency HF radar cross section (RCS) of ships as an approach to ship target classification. Results of using 32 radar frequencies to measure the fine structure in ocean current vertical shear are also shown, providing evidence of one edge of a 1-3-m deep uniform flow masked at the surface by wind-driven current shear in a different direction. Other applications of current-shear measurements, such as vector wind mapping and volumetric current estimation in coastal waters, are also discussed