波前相位差法探测器的设计

波前相位差法是利用焦面像和离焦面像通过一个相位多样性算法来拟合相位或对目标复原,这就要求采集两个图像,一个是焦面像,另一个是离焦面像。本文的设计是根据晶体的偏振原理分像,并将焦面像和离焦像同时采集到同一个CCD(Charge Coupled Device)上,这种方法保证了两个图像的同步、实时,而且光学系统简单。文中具体给出了一种新型波前相位差法探测器的设计方案、像差分析,并且模拟了波前相位差法探测器对模拟结果的影响。     

Remote Acoustic Habitat Assessment Techniques Used to Characterize the Quality and Extent of Oyster Bottom in the Chesapeake Bay

Underwater acoustic technologies may be used for remote sensing of estuarine and coastal benthic habitat in addition to more traditional methods of assessing the seabed. These systems use reflected sound energy to identify surface objects, texture, and subbottom density discontinuities, and to classify benthic habitat. We evaluated the ability of subbottom profiling systems, side scan sonar, and acoustic seabed classification systems (ASCS) to assess oyster habitat in the Chesapeake Bay. Our criteria were the systems' abilities to assess the quality and quantity of oyster shell resources and to integrate with Geographical Information Systems (GIS) technology for the charting of the seabed. Although all systems examined have previously been used for benthic habitat assessment, we found that ASCS offered the most promise as a stand alone system for mapping complex and heterogeneous habitat typical of oyster bottoms. The results from this study suggest that ASCS technology is highly suited for the identification and charting of oyster shell as well as distinguishing among different combinations of shell and fine sediments. Such systems also offer excellent linkage with GIS display and analysis capability.     

Remote Sensing of Mangrove Change Along the Tanzania Coast

This article contributes to the understanding of the changes in distribution and total area of mangrove forests along the mainland Tanzania coast over the past decade. Mangroves are recognized as critical coastal habitat requiring protection and special attention. The Tanzania coastline forms a suitable habitat for establishment of mangrove forests. Mangrove forests are distributed from Tanga in the north to Mtwara in the south covering approximately 109,593 hectares from 1988-1990 and about 108,138 hectares in 2000. The largest continuous mangrove stands are found in the districts of Rufiji, Kilwa, Tanga-Muheza, and Mtwara. Comparison of data between these two time periods shows that the geographic coverage of mangroves has no dramatic change in the past decade. The Tanzania Mangrove Management Project and other closely related programs and efforts pertaining to mangrove conservation contribute to direct restoration and natural regeneration of mangroves. This study documents the changes of mangroves and demonstrates that remote sensing and GIS offer important data and tools in the advancement of coastal resource management and ecosystem monitoring. Application of geographic information technologies is critical for improved coastal resources management and decision making for sustainable development in Tanzania.     

辅以纹理和BP神经网络的TM遥感影像分类

在提高遥感图像分类精度的方法中,将纹理信息作为扩展的特征向量加入特征空间中,是一个很有效的方法。利用地物在空间上的联系提取纹理,进而参与BP神经网络分类,实验结果表明加入纹理后明显提高了具有纹理信息的地物的分类精度。     

《遥感影像判读》课程教学的几点思考

《遥感影像判读》课程是遥感科学与技术专业的基础课,在分析了课程属性和确定了教学内容的基础上,强调应激发学生求知欲和学习兴趣,采用启发式教学,并充分发挥多媒体教学优势,挖掘现代网络教学资源,将教学与科研结合起来,以提高教学质量,达到预期的教学目标。     

遥感图像中特定目标检测的方法

随着遥感技术的发展,通过遥感手段获得的数据量越来越大,在海量的遥感数据中,如何能够快速找出有用的信息,是遥感应用重要的研究课题之一。然而,现有设备的有限处理能力和传统的图像处理方法一直是海量遥感图像数据中信息提取和分析的主要瓶颈,严重制约着数据的实际应用效率。根据人类视觉特性,提出了对于特定的遥感目标快速检测的方法,从而为目标的增强以及分类奠定了基础。     

Analyzing the agricultural transition in Mato Grosso, Brazil, using satellite-derived indices

The Amazonian state of Mato Grosso is the main production area for soybeans in Brazil and contains 31.3% of the national production as of 2009. The rapid evolution of the agricultural systems in this area shows that the region is experiencing a rapid agricultural transition. In this paper, we broke down this transition process into three steps: crop expansion, agricultural intensification and ecological intensification. We used remote sensing products to develop and compute satellite-derived indices describing the main agricultural dynamics during the cropping years from 2000-2001 to 2006-2007. Our results indicated that Mato Grosso is continuing to expand its agricultural sector, with a 43% increase in the net cropped area during the study period. Although this expansion mainly occurred in the cerrado ecoregion until the early 2000s, the forest ecoregion is experiencing expansion at this time. We observed that 65% of the crop expansion in Mato Grosso from 2000 to 2006 occurred in this ecoregion. However, we did not identify this crop expansion as the major driver of deforestation in Mato Grosso because only 12.6% of the cleared areas were directly converted into croplands. Agricultural intensification also evolved rapidly, as the proportion of the net cropped area cultivated with double cropping systems harvesting two successive commercial crops (i.e., soybean and corn or soybean and cotton) increased from 6% to 30% during the study period. Finally, we found that ecological intensification occurred because the region’s farmers planted a non-commercial crop (i.e., millet or sorghum) after the soybean harvest to prevent soil erosion, improve soil quality, break pest cycles, maintain soil moisture and set the conditions for high-quality no-tillage operations. In 2006-2007, 62% of the net cropped area was permanently covered by crops during the entire rainy season. This practice allowed the farmers to diversify their production, as shown by the positive evolution of the Area Diversity Index. Future scholars can use the method proposed in this paper to improve their understanding of the forces driving the agricultural dynamics in Mato Grosso.     

The application of remote sensing techniques to landscape level environmental research: A hybrid approach combining visual and digital interpretation

The development of new technology for use in environmental research provides us with numerous sophisticated tools such as remote sensing and Geographical Information Systems (GIS). However, throughout recent decades there have been debates regarding the appropriate use of these tools. The question still remains as to whether they can strengthen environmental research, or whether perhaps more conventional methods are better suited? This paper focuses on the use of remote sensing in environmental applications, such as strategic or regional environmental assessments. By providing a case study from Sri Lanka, it is shown how the benefits from a visual interpretation of satellite imagery can be combined with a digital supervised classification in a hybrid approach. The use of these techniques in environmental assessments is further discussed in the light of 'best practicable science' as proposed by the International Association of Impact Assessment (IAIA). The intention is not to discourage the use of digital techniques, but to discuss how they should be utilized to their fullest extent. The approach argued for here provides data of a more general and possibly integrative nature. It may therefore be well suited for the early screening and scoping stages of environmental assessments at a landscape level.     

一种高分辨率遥感影像的数学形态学滤波算法

应用数学形态学理论,结合高空间分辨率遥感影像的特点,选择包含全部方向的结构元素,设计一种基于全方位结构元素的加权多级滤波算法,用于高空间分辨率遥感影像的处理。算法中使用峰值信噪比方法自适应地确定各个方向结构元素的权重。实验结果表明：与结构元素尺度形状单一的形态学滤波算法相比,全方位结构元素的加权多级滤波算法在噪声抑制和细节保持上均有较好的性能,峰值信噪比有了更大的提高,而且更适合于对高空间分辨率遥感影像的噪声去除。     

土地利用基础图件更新软件系统的设计与开发

土地利用基础图件是新一轮国土资源大调查中系列土地调查的基础。随着我国经济建设飞速发展,土地利用状况发生了巨大变化,如何快速、准确地更新土地利用基础图件已成为亟待解决的重要问题。本文阐述了土地利用基础图件更新软件系统的需求、特点、系统功能和实现方法。该软件系统将整个图件更新作业流程一体化,实现了GPS、RS、GIS技术集成支持下的土地利用基础图件的快速更新。