准确掌握积雪覆盖信息对于气象、水文和全球气候变化研究都具有重要的意义.遥感技术在进行大范围、高频率的积雪覆盖监测中发挥着重要的作用.目前,SNOMAP算法是用于积雪遥感监测最普遍的技术手段,其核心是利用固定阈值的归一化差分积雪指数(Normalized Difference Snow Index,NDSI)进行积雪识别,但这种方法忽略了积雪光谱信息的时相变化,会产生积雪监测的误差.本文提出了一种动态NDSI阈值方法,以纯永久积雪像元的平均NDSI值作为参照系调整固定的NDSI阈值,从而削减影像光谱值波动对积雪识别的影响.以三江源地区作为研究区域,将基于每日MODIS数据进行积雪监测最佳的NDSI阈值与同日纯永久积雪像元的平均NDSI值作线性回归,通过每日纯永久积雪像元平均NDSI值的变化来调整用于积雪识别的NDSI阈值.结果 表明:①基于每日MODIS数据进行积雪覆盖监测最佳的NDSI阈值与同日纯永久积雪像元的平均NDSI值之间存在较好的线性关系,决定系数R2达到0.86;②三江源地区动态NDSI阈值的范围为0.29～0.37,其平均值在0.33左右,说明MODIS全球积雪面积产品中将NDSI阈值取为0.40会低估三江源地区的积雪面积;③与采用固定NDSI阈值0.33的监测方法相比,动态NDSI阈值法近似率、总体分类精度和F值的平均值分别提高了5.17％、0.70％、1.14％.
生态环境是人类社会生存与发展的基础.快速发展的遥感技术显著推动着生态环境遥感监测能力的提升,有效支撑了国家生态文明建设.从1980年天津一渤海湾环境遥感试验开始,经历了近40年的发展,遥感监测技术已经广泛应用于生态、大气、水、土壤等生态环境保护各个方面,取得显著成效.本文回顾了我国生态环境遥感技术近40年的发展,通过典型或重要应用案例,系统梳理了遥感技术在生态环境监测、对地观测能力、支撑生态文明建设等方面应用的发展历程.生态环境遥感监测能力发展主要表现在应用领域逐步扩大、监测精度明显提升、监测时效大幅增强;对地观测能力发展主要分为国外卫星为主期、环境卫星发展期、高分卫星应用期3个阶段;支撑生态文明建设的重大事件主要包括全国生态状况定期调查评估、污染防治攻坚战、应急与监督执法等方面.本文结合国家战略和技术发展,对今后生态环境遥感的发展提出了一些思考.
针对目前国产卫星对气溶胶遥感监测应用较少的情况,本研究综合暗象元和SARA算法优势,基于FY-3D MERSI2数据构建了一套气溶胶光学厚度（Aerial Optical Depth, AOD）快速遥感反演方法。首先,引入了传统暗象元算法中的地表反射率经验关系,然后利用AERONET长时间序列的地基观测数据,构建了红波段和蓝波段气溶胶光学厚度、不对称因子和单次散射率之间的关系,最后利用MOD04和AERONET的AOD产品对研究反演结果进行了验证和评估分析。结果发现:①本研究反演的AOD不仅保持了与MODIS的气溶胶产品空间分布的一致性,而且合理地呈现了AOD的高值分布,改进了MOD04气溶胶产品在云和亮目标方面反演缺失问题;②利用AERONET地基观测结果对本研究获取的MERSI2的AOD反演结果进行了对比分析,发现二者具有较高的线性相关性,蓝波段AOD线性相关系数超过0.85;③利用MERSI2数据完整地捕捉到了2018年3月9—14日京津冀及周边区域的一次重污染过程中气溶胶时空分布变化情况,这也说明了FY3D卫星具备良好的气溶胶遥感监测能力,为我国灰霾监测和预警提供参考依据。本研究对大力发展国产卫星在大气环境遥感的应用有重要参考意义。
探索艾滋病疫情的空间格局和时空演化特征,发现其分布和流行规律,对促进艾滋病防控工作具有重要意义.本文基于1997-2016年中国艾滋病省级发病率资料,利用空间自相关技术探测艾滋病疫情的空间格局,并使用重心轨迹迁移算法进行时空演化分析.结果 表明:中国艾滋病疫情在省级尺度上具有较强的空间依赖性.1997-2016年,中国艾滋病疫情的全局空间关联程度从弱变强,而且存在进一步强化的趋势;疫情总体呈现“南重北轻,中部过渡”的空间格局,可将中国艾滋病发病率在局部发生空间自相关的区域划分为以内蒙为代表的北方疫情冷点片区和以广西为代表的南方疫情热点片区;中国艾滋病疫情的总体流行程度不断加深,且具有明显的地域差异性,在空间上表现为非均衡增长.因此,今后的艾滋防控工作必须在传统预防手段的基础上注重疫情扩散的时空规律,重点加强对疫情热点区域和高风险传播方向的管控,以达到区域协同、精准防控的目的.
在国家大力推进新型城镇化和落实城市群空间规划的背景下,评价城市群土地生态安全水平,并以此为限制条件预测城市群未来土地利用格局,对城市群可持续发展具有重要意义。本文以环鄱阳湖城市群为研究对象,对城市群土地生态安全格局和变化进行分析,根据土地生态安全评价结果设置自然发展情景和生态保护情景,结合多分类Logistic回归和多标准评价方法（MCE）,构建CA-Markov模型,预测2种情景下2030年土地利用格局并进行对比分析。研究结果表明:①2005、2010和2015年,环鄱阳湖城市群网格平均生态安全值分别为0.574、0.573和0.571,空间布局上呈现"中部低、东西高"的特征;②预测2030年,自然发展情景下新增城镇用地主要位于九江市、上饶市和南昌市,生态保护情景下限制城镇用地和其他建设用地向土地生态安全高值区扩展,使得城镇用地和其他建设用地扩展更加集中;③预测生态保护情景下,高生态安全区面积比自然发展情景下多39.39%且分布更加均匀,包括鄱阳湖周边区域、九江市中部以及新余市和吉安市,城市群生态安全得到有效保护。该研究可为环鄱阳湖城市群土地利用规划及生态保护提供参考。
城市的快速扩张不断改变着土地资源的转化,带来了诸多生态环境问题。分析和模拟城市扩张的机制,并对城市未来土地利用变化的风险进行预警,利于合理调控城市的发展。本文提出了一种基于地理分区和未来用地模拟（Future Land Use Simulation, FLUS）模型的城市扩张模拟模型,用于模拟和预测复杂的土地利用变化。该模型利用多指标数据进行空间聚类,耦合地理分区结果进行城市扩张模拟。珠江三角洲2005—2015年的城市扩张模拟结果显示,分区下的模拟精度（FoM=0.2329,提高了9%）明显高于未分区,说明不同分区在土地利用转化上存在空间差异,该模型能更有效地模拟城市土地利用变化。另外,本文构建了一种城市扩张预警指标评价体系,用于评估城市扩张的警情。根据在2005—2015基础上预测的2025—2045年土地利用变化结果,对珠江三角洲城市扩张进行多尺度预警分析。综合预警结果显示该区域大部分城市至2045年城市扩张警情将达到中警和重警,其中东莞警情一直维持在重警。由此,未来需要加强对珠三角城市扩张的宏观调控,以此来缓解未来城市扩张的警情。
Since the Enlarged Terrestrial Atlas(1541) compiled by the outstanding cartographer Luo Hongxian(1504-1564) in the Ming Dynasty and the incoming western precise mapping technology brought by Matteo Ricci, China's cartographic technology had entered the academy of modern cartography, and then gradually matured during Ming, Qing and Republic of China periods. With the constant development and application of today's cartography, the summarized map symbols and ordinary two- dimensional maps can no longer meet the needs of readers. Cartographers began to explore new types of expressions, such as Visual Reality and3 D maps, which resembles the traditional meticulous methods appeared in old Chinese maps. Therefore, it's necessary to study the cartography technology and expression method in Chinese Modern Cartography period. Basing on plenty old maps produced in Chinese Modern Cartography period and related academic materials, this paper overviewed the cartography technology in these periods, summarized the map elements and expression methods adopted, in order to provide some inspirations to the development of today's Chinese cartography.
Map drawing in near modern China(Ming Dynasty, Qing Dynasty and Republic of China) is the best representation of Chinese ancient cartography. The later stage of Chinese feudal society was the transition period that ancient cartography was changing to modern cartography. It's necessary to research the maps made in the near modern period. Provincial and regional maps of near modern China reveal more characteristics than other types of maps in that period. Through collecting the maps of near modern China, the characteristics of provincial and regional maps of near modern China were discussed from two aspects,including the arrangement systems and expression methods. The arrangement systems of provincial and regional maps in near modern China were further divided into two parts, one is the different publication formats during the same period, such as single pieces of maps from historical records and maps included in atlas and encyclopaedia, the other is the arrangement system classification and subdivision based on administrative divisions. The expression methods of provincial and regional maps in near modern China were divided into three parts, including the expression method characteristics of single provincial and regional map,provincial and regional maps in encyclopaedia, and provincial and regional atlas. It is of significant value to research the provincial and regional maps of near modern China. Through these studies and comparisons of modern atlas within various periods, we can further study the peculiarities of provincial administrative division, inner structure of provincial physical geography unit and strengthening management of province and region. This paper lays a foundation to the further study of the provincial and regional maps of near modern China, and also provided a reference for the drawing of provincial and regional maps and the compiling of atlas in modern China.
The kilometer grid style and landscape painting style are two features of Chinese ancient maps. However, the positioning accuracy of ancient maps is very low due to the lack of a clear mathematical basis. It is difficult to apply map processing, map correction and geo-referencing on these ancient maps. This paper divides the current positioning datum of ancient maps into three types: one with no geo- reference, one with partial geo- reference, and one with definite geo- reference, and explores the map repairing methods from the following aspects: data selection, pre-processing, radiometric correction, and geographical information recovery. Besides, this paper takes some Chinese near modern maps as examples in several map matching experiments, adapts different spatial positioning methods, such as feature point correction, matching by grid, and relative position shift, to complete corrections between Chinese ancient maps and modern maps, and focuses on the mathematical relationship in the square grid maps and different geo-reference systems and projection systems. Finally, we try to establish the mathematical relationships between the corrected ancient maps and the accurate maps, and study the relationship between"six key points of mapping"and the modern coordinates system.
Maps of scenic spots in ancient China were originated from Chinese landscape painting and thus associated with it closely. At the same time, the ancients paid more attention to the artistic features of maps due to time limitations as well as the lack of ancient scientific requirements for mapping. Ancient map of scenic spot is products of China's unique art and culture. It is the combination of Chinese traditional ideology and culture, calligraphy, painting and the other types of arts and it has important cultural and artistic value. This paper discusses the artistic characteristics of ancient scenic spot maps in terms of cartography,generalization, scaling, orientation, color, annotation and traditional ideology. Also, the corresponding artistic characteristics are presented by the attached maps to show the beauty of ancient art. Chinese culture is extensive and profound, and it contains a variety of ideas, such as Confucianism, Taoist thought and Buddhist thought. These thoughts have a profound impact on the development of ancient map art. Modern map pays great attention to the scientific nature leading to the lack of artistic quality.Nevertheless, the ancient Chinese map of scenic spot is inspired by Chinese traditional ideology, culture, calligraphy, painting and other forms of art,which can well make up for its defects. Studying the artistic features of ancient scenic spot maps not only has an important reference significance for the development of contemporary cartography, but also plays an important role for inheriting Chinese traditional culture, therefore we should dig deeper into these cultural treasures and also introduce Chinese culture to the world.
China is a country with centuries' old historical civilization. City culture is one of the most important parts in the long history of the Chinese splendid national culture.Following the prosperity of human civilization, a large amount of cities with various sizes appeared and kept growing continuously. Some cities have developed into world-famous with abundant historical culture and significant historic value, which are originated from the achievements of Chinese ancient civilization. In the present day, when cities are developing rapidly, it isparticularly important to study the evolution of cities since ancient times. One efficient way to achieve this is to study city maps which reflect the spatial pattern of cities in a relatively accurate sense. Therefore, city maps can provide great reference values for exploring the changesin city patterns from a historical view. This paper aims to study the modern city maps produced during the period from the Ming Dynasty to the Republican period. In terms of the inheritance of traditional ancient city maps and the developments encouraged by the western cartography, this paper intends to explore the characteristics,developing trends and values of Chinese modern city maps. On one hand, modern city maps had not completely got rid of the features of Chinese traditional city maps from the aspects of method and content; on the other hand, modern city maps had also been influenced and motivated by western knowledge. Therefore, Chinese modern city maps were gradually developing towards diversification, thematization and modernization during the process of inheritance and development, reflecting the trait of city development and regional features at that time. This paper also applied the case study method to explore the Chinese modern city maps with typical examples from various time and cities, and to further discuss and make comments on the representations,contents, techniques as well as significant values of these maps.
“HaiGou Tuzhi”is an atlas of the world, which was edited by Wei Yuan, who complied with the great trust of Lin Zexu. Based on the“four continents annals"created by Lin Zexu,“HaiGouTuzhi”was then published three times in a row between 1842 and 1852. Some mainstream scholars in China laugh at“it's childish”, and China's imperial palace put it on the shelf. However, it was spread to Japan and the book sold quickly, which effectively promoted the reform revolution of Japan started in the middle of the 19th century. Until the late 20th century, China's implementation of reform and opening launched the research boom of"HaiGou Tuzhi" by historian, geographer and cartographer, and they speak highly of it as "the most comprehensive magnum opus on the world for geography and history", "the first world atlas compiled in the near-modern of China", and so on. Firstly, this paper analyzed "HaiGuo Tuzhi" with its 100 volumes, which including 75 maps and 880,000 texts divided into 10 parts, including chapters of"The preface","Coastal defense","Maps","Annals","Religious calendar","Countries in general","Coastal defense in general", "Foreign affairs record set", "Weapons and equipment", and "The earth’s astronomical theory". In the meantime, this research outlines the multi-angle studies and comments on"HaiGuo Tuzhi"from China and Japan, mainly discusses the values of cartography such as"designing idea”,“content arrangement”,”compiling technology"and so on;as well as introduces the editing strategy of "Learning from Foreigners to Competing Foreigners", and successful experiences and focuses on distinguishing data authenticity and the comprehensive genre in editing“HaiGuo Tuzhi”. All of these have important practical significance. At last, we suggest that today's cartographer should try to absorb the cartography“nutrition”from"HaiGuo Tuzhi"and positively response to the new requirements of the era of deepening reform and opening up, to compile and publish a new comprehensive atlas of the world with"real data, large-scale and integrated information, and provide services to people"as soon as possible.
Land surface temperature(LST) is one of the key parameters in land surface processes, and hemispherical radiative surface temperature is also an important input parameter for land surface models. However, notably the LST derived from satellite scale data is affected by the variation of viewing zenith angles. Therefore, it is necessary to develop methods to estimate the hemispherical radiative temperature from the satellite- derived LST before inputting the hemispherical radiative temperature into land surface models. This paper firstly analyzes the relationship between the directional and hemispherical radiative temperatures simulated by a thermal-infrared radiative transfer model and a parameterized model for flat and homogeneous canopy, considering leaf inclination distribution function(LIDF), leaf area index(LAI), solar zenith angle and viewing azimuth angle. Then, a best directional radiative temperature is proposed to substitute the hemispherical radiative temperature. In addition, this paper also briefly describes the angular effect of the radiative surface temperature via field experimental study. The experiments were conducted over a homogenous and flat grassy lawn using two KT-15.85 D infrared radiometers mounted on a multi-angle observation device. The grass radiative surface temperature under different viewing angles was measured by one radiometer through rotating the arm of the multi- angle observation device. The radiative surface temperature at nadir was measured by the other radiometer on a fixed arm. The results reveal that the radiative surface temperature increases with the increase of viewing zenith angle and it depends slightly on the variation of viewing azimuth angle. Comparing the off- nadir radiative temperatures to those measured at nadir, it exhibits a maximum difference of 2.7 K when the viewing zenith angle is at 75°, which implies that the angular effect of infrared radiation does exist. Comparing and analyzing the directional and hemispherical radiative temperatures, we found that the directional radiative temperature measured at a viewing zenith angle of 51° can be the best substitute for the hemispherical radiative temperature when the LAI is below 1.0.
At the end of the 16 thcentury, western cartography technology was introduced to China. AT this moment, the relatively independent traditional Chinese cartography was influenced by the western country. Until the formation of the Republic of China,western precise mapping technology had influenced the development of traditional Chinese cartography in many aspects, including the latitude and longitude control and the projective transformation. The main research direction of this paper is focusing on 3historical periods of China, including the end of Ming Dynasty, the beginning of Qing Dynasty and the end of Qing Dynasty, and emphatically analyzing the background of western cartography technology at every period. Under its influence, some map works emerged. The changes of traditional Chinese cartography are summarized. At first, the traditional Chinese cartography developed independently and resisted western cartography. But afterwards, the former fully absorbed the latter. Finally, the traditional cartography which was transformed from the old method to the new method built up the modern cartography theory which meets the development demand of China. Furthermore, this paper summarized the corresponding historical experience, hoping to illuminate the mapping personnel nowadays.
This paper is finished on the purpose of writing an article of astronomical map for“Near-Modern Chinese Map Annals”, and we take a systematically study on the outstanding achievements of Chinese ancient astronomers in founding the "Theory of Sphere-Heavens", manufacturing“Armillary Sphere”, implementing astronomical observation and astronomical geodetic survey, and creating astronomical maps. The earliest recorded“Star table”was created by "Shi Shenfu" during the warring states period before in the 4th century B.C.;then,“Zhang Heng”created"Theory of Sphere-Heavens"and made the first“Turn Leaky Armillary Sphere”in the world during Han Dynasty in the 2nd century;Zhang Sui completed the national astronomical geodetic survey at 13 spots across China and is the first one who calculated the 1° arc length of local meridian at latitude 34° north to be 110.6 kilometers during Tang Dynasty;and Guo Shoujin”implemented"Universal Measurement"and"Leveling"during Yuan Dynasty. The ancient Chinese astronomical map discovered so far including:“the astronomical figure on a paint box cover in the Tomb of Marquis Yi of Zeng in Sui county before the warring states period of China"which is created in 433 B.C.;“the start figure on the tomb murals indicating four quadrant symbols and 28 lunar mansions”which is created in the Western Han Dynasty in Xi’an city, Shaanxi Province;the"DunHuang star map"which contains more than 1350 stars and is created during 705-710 A.D.;the“Suzhou stone carving astronomical map"which contains more than 1440 stars and is created by“Huang Chang”in 1190 A.D.;the"constellation chart of crossing seas”which is created by Zheng He in 1405-1433 A.D.;the"Star Barrier Figure"which contains 1812 stars and is created by“Xu Guangqi”in the early 17th century;and the“total star map on the north and south sides of equator”which contains 1876 stars and is created by“Verbiest”in the mid 17th century. In a word, the ancient Chinese astronomical geodetic results provided foundation for global positioning, and the“circular methods”of ancient astronomical map are similar to the“azimuthal projection”, which greatly improved and enhanced China's traditional cartography. The scientific methods of making the astronomical map with“circular”showed the excellence of“Traditional Cartography Family”, and made important contribution in the process of developing Chinese traditional cartography.
The navigational charts in China's Ming dynasty are famous all over the world at that time, such as the‘Hydrographic Guide Map'so far discovered in the early Ming Dynasty, which collected the detailed shipping route to transport grain from the south to the north along the coastline between Ningbo and Liao river over thousands of years; and the‘Zheng He Navigational Chart', which reveals the style and features in a period of great prosperity on Chinese ancient navigation achievements and navigational chart techniques and includes 14 seaway routes crossing Asia, Africa and Europe recognized as the first one in the world. The inheritance and development of the‘Maritime Silk Road'since Han dynasty, once again advocates the main purpose of the traditional business between china and foreign countries, which is the culture exchange and local product trading. The‘Sea Route Book'recorded the navigational guide of South China Sea as the legacy and at the cost of generations of fishermen's life during the ancient times. The‘Ryukyu Nautical Charts' shows the distribution of navigation routes that ancient Chinese navigators recorded during their visits to Ryukyu, Taiwan, Japan and other places across the east ocean of China. The‘Selden Map of China'keeps the functions of a general nautical map, and perfected the nautical chart series of Ming dynasty. This paper also systematically discusses the realistic style of the navigational charts, their matching descriptions or drawings in Ming dynasty, as well as the adoptions of‘Opposite Scenery Method',‘Lead Star Board',‘Water Compass',‘Astronomical Observation Instruments' ‘,Speed Detection On Board'and other unique techniques.
Plant community is a significant content in the ecosystem. Traditional investigation method for plant community is mainly based on statistical sampling, which is limited by the data acquisition from complex terrain areas. In contrast, highresolution remote sensing technique provides a convenient way to quickly access data in a large area. To overcome the shortcomings derived from the high dimensional features, which is caused by related data increasing, we choose the algorithm of projection pursuit learning network(PPLN) along with field samples of typical plant communities to realize a fast classification on the vegetation in the east of Shenzhen. Then,in the experiment, the spectral and texture information extracted from Pleiades images,and the terrain interpolated from topographic map are selected and used to build high dimensional features, which is crucial to the vegetation classification using remote sensing images. The learning network for projection pursuit is applied to discriminating the typical communities in both plantation and natural secondary forest in the study area. Compared with Maximum- likelihood classification(MLC) and Support Vector Machine(SVM), PPLN can achieve more accurate results for plant community classification. As a conclusion, the plant community classification with PPLN meets the requirements of the investigation project,achieves the quick updating of some basic information related to forest resources, and looks forward to involve in some other ecological research as well.
Machine learning technology has been widely used in remote sensing image classification. Extreme learning machine(ELM) is proposed recently for image classification, but the regularization and kernel parameters(C, σ) of ELM have significant influence on classification performance. In this paper, an ELM classifier with firefly algorithm(FA)- based parameter optimization is proposed for hyperspectral image classification. Firstly,FA algorithm is used for band selection in order to reduce the computational load of hyperspectral image classification. Then, the parameters(C, σ) of ELM are optimized by FA with respect to the classification accuracy. In our experiments, the firefly algorithm is also compared with other parameter optimization algorithms such as genetic algorithm(GA) and particle swarm optimization(PSO). In addition, the support vector machine(SVM)-based classification algorithm is also implemented for comparison purpose. The experiments are conducted on three classical hyperspectral remote sensing data. Results indicate that the performance of ELM method is better than SVM method from the aspects of classification accuracy and running time. Our experiments successfully prove that the proposed algorithm can provide a better performance for hyperspectral image classification.
