基于视觉特性的影像增强算法研究

遥感影像对比度调整是影像预处理中的关键部分。分析人的视觉特性发现：影像中不同区域特征变化被感知度有所差异。相对于高频区域及对角线方向,人眼更容易感觉到平缓部分的特征变化。以往的对比度增强算法并没有考虑这一视觉特性,提出了一种基于视觉特性的影像增强算法。实验表明,该算法在较好的保持影像细节特征的同时,改善了影像的对比度,得到了较好的视觉效果。     

遥感影像变化检测在地形图快速修测中的应用

首先介绍地形网修测中常规判读地物地貌发生变化的方法,以及将变化检测技术应用于地形图修测中的必要性;其次介绍变化检测的基本原理、发展历史、国内外对变化检测概念的不同定义以及变化检测技术的特点和应用范围;紧接着从地形图快速修测这一客观需要出发,简明扼要地叙述变化检测方法的选择、变化检测的一般过程、变化检测结果在地形图修测中的应用,并结合变化检测的精度评估公式分析将变化检测技术应用于地形图修测工作中的实际效率;最后展望变化检测技术在地形图快速修测中的应用前景。     

基础电子地图符号尺寸设计的研究与实践

在调查实验结果的基础上,分析了对基于基础地理数据的电子地图（基础电子地图）符号尺寸设计的影响因素和设计原则,对电子地图符号尺寸设计、提高符号表现力进行了一些理论探讨和实践尝试。     

Occurrence and distribution pattern of Palaemon spp. shrimps in a shallow submarine cave environment: a study case in South‐eastern Italy

The common shrimps of the genus Palaemon are often reported as living in Mediterranean submarine caves. The present study quantifies the distribution pattern of a Palaemon spp. populations throughout 1 year of observations in a shallow submarine cave in South‐eastern Italy, Ionian Sea. The cave was subdivided into six sectors from the entrance towards the inner portion of the ‘blind cave’ and 16 dives (four per season, during both day and night) were performed with SCUBA equipment. The population was estimated in situ using visual census. Four different species of Palaemon were identified. This study has shown that Palaemon spp. assemblages live throughout the year in submarine caves. Moreover, the results suggest submarine caves play an important role in the biology of Palaemon spp. populations, by providing refuge, juvenile recruitment and food resources.     

林业数据挖掘与可视化的应用分析

面对海量的林业空间与非空间数据,提取隐含的信息是"数字林业"急需解决的关键问题之一。数据挖掘和可视化是处理和分析海量空间数据的有力工具,利用它们可以有效地剖析隐藏在数据背后的信息与知识,为我林业规划与决策提供服务。本文将空间数据挖掘和可视化技术整合为一个有机的整体,集成两者的优势,阐述了可视化技术在空间数据挖掘研究中的意义。并讨论了空间数据可视化表达模式和可视化与空间数据挖掘的整合。针对林业资源数据的特点,提出在可视化表达空间数据的基础上对林业数据的多维信息进行综合分析。最后,开发了原型系统,初步实现了林业数据可视化挖掘。     

基于描述方法的地图符号表达及实现

论文以图形视觉变量以及BNF为理论,采用纯文本方式对点、线、面符号进行描述、组织,提出了一套地图符号库描述规则,该规则应用与软件平台无关,可以跨平台共享地图符号资源,提高系统的建设效率,并以1:50000地形图图式为例进行了符号的绘制与使用。     

高分辨率影像农田信息提取方法

选取河南省安阳市某地冬小麦长势良好的Quick Bird影像,首先应用数学形态学的开运算对高分辨率遥感影像进行分割,将种植冬小麦的农田与反射率较高的空地、道路、农村居民地进行区分,人工选择并提取需要分析的农田区域,计算其边界并进行细化,最终提取农田边界信息。整体处理流程基于VC++6.0编程实现。     

基于射线追踪的视场范围算法

在海量地形数据可视化技术中，视场范围计算方法直接影响显示效率。本文提出了基于射线追踪法的视景体投影算法，投影后在二维平面上进行二次裁减。试验表明，该算法具有较高的效率。     

Combining Gaia Windows: The Method and Simulations

During the 5-year-observational phase of Gaia several one-dimensional observations will be obtained from the same objects at different epochs and transit angles. Combining the information from all the transits to produce a single two-dimensional image is scientifically important as this will allow to detect much fainter stars in the vicinity of the main source than otherwise possible from single observations on-board the satellite or from individual transmitted patches. Most of the emerging objects will be physical companions, but some background/foreground objects will also be found. The combination procedure further increases the image resolution in the across scan-direction. The procedure consists of combining patches that are stretched back to 2-D windows, only possible since the centroid positions of the windows are known. The initial image window from which the patches originate is not square, but elongated along the scan-direction if the Astro AF11 field of view is used in the current calculations. Transit angles can take any value between 0^∘ and 360^∘. The window combining method is a simple mapping procedure that is fast and should handle all realistic complexities occurring during the Gaia data reduction. The method is not intended to be a perfect image restoration technique, but its purpose is to fulfill the scientific requirement of detecting faint neighboring sources existing in the close vicinity of the main targets. In this study we show examples of the combined windows and illustrate how faint companions around primary targets could be detected. We investigate the performances and limitations of the method and discuss possible complexities that might occur during the final data analysis.     

回采工作面采空区瓦斯涌出规律的数值模拟研究

从分析采空区内部的瓦斯源出发，用负指数函数描述各煤层瓦斯涌出强度的衰减过程。用迎风格式的有限元方法求解了非均质回采采空区流场的瓦斯-大气两相混溶渗流-扩散方程，以可视化技术描绘了采空区瓦斯涌出与风流交换和瓦斯分布变化规律的流体力学原理。模拟表明，采空区绝对瓦斯涌出量随工作面风量呈衰减变化。而与采空区瓦斯涌出强度呈显著地线性增加，与工作面推进度呈线性递减（但递减幅度不大）；工作面风量的突然增大会对瓦斯涌出量在短时间内（8min）产生剧烈的高峰影响，用逐渐增风方法可以避免瓦斯高峰涌出的影响。提出了采空区瓦斯涌出强度的概念，论证了用瓦斯涌出强度衡量采空区瓦斯涌出的科学意义。