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1.
Nearest neighbor classifiers have not been widely used by remote sensing practitioners. The lack of acceptance of these classifiers may be partially due to their notoriously slow speed of execution which makes them impractical for the classification of mega-pixel images. However, training data reduction, distance measure optimization, and neighbor searching algorithms based on the modified k-d tree can speed nearest neighbor classification substantially. 相似文献
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Object-oriented image classification has tremendous potential to improve classification accuracies of land use and land cover (LULC), yet its benefits have only been minimally tested in peer-reviewed studies. We aim to quantify the benefits of an object-oriented method over a traditional pixel-based method for the mixed urban–suburban–agricultural landscape surrounding Gettysburg, Pennsylvania. To do so, we compared a traditional pixel-based classification using maximum likelihood to the object-oriented image classification paradigm embedded in eCognition Professional 4.0 software. This object-oriented paradigm has at least four components not typically used in pixel-based classification: (1) the segmentation procedure, (2) nearest neighbor classifier, (3) the integration of expert knowledge, and (4) feature space optimization. We evaluated each of these components individually to determine the source of any improvement in classification accuracy. We found that the combination of segmentation into image objects, the nearest neighbor classifier, and integration of expert knowledge yields substantially improved classification accuracy for the scene compared to a traditional pixel-based method. However, with the exception of feature space optimization, little or no improvement in classification accuracy is achieved by each of these strategies individually. 相似文献
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浑善达克沙地南缘榆树种群的大小结构和邻体格局 总被引：4，自引：1，他引：4
浑善达克沙地作为京津地区沙尘暴的重要沙源地引起了生态学界的广泛关注。榆树是浑善达克沙地的优势种,榆树疏林在浑善达克沙地成缀块状分布,对于该区域生态系统的整体性和多样性维持以及防风固沙等方面具有重要意义。研究浑善达克沙地南缘榆树种群的大小结构和邻体格局的结果显示:榆树种群的平均胸径为25.40 cm,最小胸径为6.37 cm,缺乏幼树,种群更新不良。榆树邻体格局研究显示:榆树种群呈丛分布,取样个体到最近邻体距离的平均值是7.13 m,在4 m以下的占55.0%,10 m以下的占72.6%。两个个体互为最近邻体的榆树占了71.4%,具有成对现象,成对现象对榆树有明显影响。最后对榆树疏林存在的问题及保护措施等进行了探讨。 相似文献
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对不同的地貌区进行空间内插时选择的适宜方法不同,以典型丘陵地貌区长春市净月潭地区的高程为研究对象,用ArcGIS 9.2分别作反距离权重法、最近邻点法、趋势面分析和克里金法做高程内插。应用交叉检验方法对其内插的精度作出分析,检验其科学性和可靠性,得出反距离权重法、最近邻点法、趋势面法、样条函数法和克里金法高程内插的不同精度,并对各种方法的适用性进行讨论。结果表明最近邻点法精度最高,以下依次为普通克里金插值法、样条函数、反距离权重法、趋势面法。为类似于净月潭地区的丘陵地貌区高程内插提供选择参考。 相似文献
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贵州洞穴空间格局及影响因素分析 总被引：1，自引：0，他引：1
以贵州水文地质图和地形图为基础,利用ArcGIS对境内近5000个洞穴洞口海拔、经纬度提取及所在地层、岩性、水系、构造划分,并运用最邻近指数、空间分析与耦合分析处理,研究了贵州全省4960个洞穴的分布特征,探讨了洞穴空间格局与地理要素之间的关系。通过对贵州洞穴进行点格局分析,得出最近邻指数为0.53,泰森多边形检验其变异系数达72.469%,符合凝聚分布模式;并采用点密度函数将全省洞穴划分为4个集聚区和1个弱影响区,即遵义—铜仁强影响区、毕节强影响区、黔西南—六盘水强影响区、贵阳—安顺—黔南强影响区和黔东南弱影响区。其中贵阳—安顺—黔南强影响区是洞穴最主要的分布区,占全省洞穴总量的36.63%,该影响区面积占全省面积的24.67%。贵州洞穴分布呈西密东疏的分布特征,形成明显的“片状”格局。在其研究背景下,地层、岩性、构造、气候、水文、海拔等因素主要制约洞穴的分布、数量、空间格局及其发育。 相似文献
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《Geomorphology》2007,83(1-2):48-57
Dune fields have recently come to be recognized as self-organizing systems that can be seen progressing from states of disorganization or randomness to uniformity. Dune systems can be highly sensitive to changes in factors, such as climate and sediment transport, that determine system state. Changes in climate and sediment state can take time to work their way through a dune system; this, in turn, leads to spatial heterogeneity in dune field organization. Using the Coral Pink Sand Dunes in southern Utah as a model, this study tests nearest neighbor analysis adapted as a method to objectively identify and characterize differences in two dimensional dune patterns within a dune field and to identify changes in dune patterns over time. Reducing transverse and barchanoid dunes from linear to three-point features in planar space emphasizes the clustering that occurs when dune lengths and wavelengths are more disorganized or random. This clustering may be in response to a system perturbation, such as an influx of sediment, and is reflected in lower nearest neighbor index (R) values. As the system adjusts to the perturbation and moves towards steady state, dune length and spacing increase through migration and coalescing of smaller dunes; the resulting higher R values reflect this move towards greater uniformity in dune pattern. With the organizational states of dune systems recording feedback to changes in extrinsic climate and sediment factors, nearest neighbor analysis provides a proxy measure of system stability. 相似文献
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大尺度景观结构指数的因子分析 总被引：13，自引：1，他引：12
基于遥感和GIS技术,尝试对大尺度下陆地景观结构指数进行因子分析。根据生态区划计算描述中国陆地景观结构的13种景观结构指数,包括斑块密度、最大斑块指数、边界密度、面积加权斑块形状指数、面积加权斑块分维度、平均最近斑块距离、最近斑块距离的标准差、最近斑块距离的相异系数、蔓延度、分布邻接指数、结合度、香农多样性指数、辛普森多样性指数。在相关分析的基础上,对其中12种指数进行因子分析,并采用前3个公因子分析中国陆地景观结构,3个公因子的方差累积贡献率达88.8%,分别定义为斑块多样性因子、斑块形状复杂性因子和斑块分布均匀性因子。计算表明,在人类活动影响强烈的生态区,这3个公因子取值都比较小,反映斑块类型多样性减少、形状复杂性降低、分布趋于均匀。 相似文献
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通过最邻近距离法定量描述了巴丹吉林沙漠高大沙山空间分布特征,分析和讨论了巴丹吉林沙漠高大沙山的主要成因和影响因素。结果表明:研究区内高大沙山空间分布的均匀程度整体上呈现出由西向东逐渐增大的趋势,而东南部靠近雅布赖山地区略有降低,最邻近指数R主要分布在1.29~1.63。沙山底面积和沙山绝对高度在空间上同样呈现出由西向东逐渐增大的趋势,但巴丹吉林沙漠高大沙山空间分布均匀程度的发展并不直接受到所在地海拔的影响。巴丹吉林沙漠高大沙山在空间分布上具有较高的自组织特征,而风力作用是塑造和维持巴丹吉林沙漠高大沙山巨大高度与自组织排列特征的主要力量。 相似文献
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The topic of geoprivacy is increasingly relevant as larger quantities of personal location data are collected and shared. The results of scientific inquiries are often spatially suppressed to protect confidentiality, limiting possible benefits of public distribution. Obfuscation techniques for point data hold the potential to enable the public release of more accurate location data without compromising personal identities. This paper examines the application of four spatial obfuscation methods for household survey data. Household privacy is evaluated by a nearest neighbor analysis, and spatial distribution is measured by a cross-k function and cluster analysis. A new obfuscation technique, Voronoi masking, is demonstrated to be distinctively equipped to balance between protecting both household privacy and spatial distribution. 相似文献
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基于GIS-SDA的居民点空间分布研究 总被引：22，自引：0，他引：22
空间数据分析(SDA)与GIS相结合是研究地理现象空间分布规律的重要方法。借助1994年和2004年两期RS图像,得到徐州市居民点空间分布数据,运用GIS-SDA方法研究徐州市1994年和2004年的居民点空间分布模式,并总结了11年间居民点空间分布的动态演变规律。通过最近邻距离分析(运用R统计量)得出徐州市居民点空间分布总体上呈现集聚趋势,且2004年的集聚程度比1994年低;通过计算居民点空间分布的K函数值,发现随着研究尺度的变化,1994年和2004年的居民点空间分布集聚程度均出现先增后降过程。运用核函数与泰森多边形法计算两个年份的居民点密度分布,核函数法能够从总体上反映徐州市居民点密度空间分布的地域差异,而泰森多边形法对居民点密度空间分布的细部差异较敏感。 相似文献
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场域视角下清代北京宣南雅文化核心区范围及空间关联特征 总被引：1，自引：1，他引：0
清代北京“宣南文化”是以名人雅士为主体的“雅文化”,宣南地区可视为雅文化大场域。抽提影响雅文化形成的三类核心建筑载体要素：寺庙、名人居所、会馆,在场域视角下用GIS分析三要素微场域的空间分布、关联和聚集,从而递进探析宣南“雅文化核心区”区域性子场域的存在和范围,以及内部要素微场域聚集形成的空间特征和成因。结论包括：① 雅文化核心区范围为清代北京外城西部的中部、中北部“双肾”形区域;其与俗文化区空间临近,没有绝对清晰的边界,投射出雅俗文化间的排斥依存、融渗互补。② 核心区子场域内部的空间关联特征为“三要素、两聚集”的“链条式”“中心-过渡中心”层次性空间结构。③ 量化印证微观街区尺度下“同乡之情”是名人居所与会馆聚集的内在驱动力。在北京“文化中心”战略定位下,为传统文化保护更新策略的提出奠定历史研究基础;在历史文化研究方面,具有方法上的实践创新和借鉴意义。 相似文献
13.
Rusty A. Gonser Ryan R. Jensen Samuel E. Wolf 《Applied geography (Sevenoaks, England)》2009,29(4):527-532
Deer–vehicle collisions (DVCs) are a constant problem in North America that cost millions of dollars of damage and loss of human life. This study investigated the spatial relationship of DVCs for a county in western Indiana using nearest neighbor analysis, chi-square test of independence, and a landscape metric: the percentage of like adjacencies. The study was able to show that DVCs are not randomly located, and that habitat type and structure may play an important role in the location of DVCs. 相似文献
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Transportation as a means to support industrial development can impact the economic development of important agricultural heritage sites. Because the central towns in mountainous areas have weak economic interactions with each other, an appropriate method is needed to evaluate their transportation accessibility. This paper takes the Honghe Hani Rice Terraced System (HHRTS) as a study area and develops a model to determine shortest time-distances from central towns in the study area to the nearest high-grade city as a way to evaluate transportation accessibility (TA). We then analyze the relationship between the accessibility of these towns and their economies. The study finds that the TA of the central towns in HHRTS is not good as a whole. More than 70% of the towns are more than 1 hour away from their nearest high-grade city. Of the four counties in the study area, Yuanyang County has the best traffic conditions, while Lvchun County has the worst traffic conditions. The central towns in the northern and middle regions have better TA than those in the west, southwest and east margin regions. The small-scale rural economy has little dependence on the transportation network, while secondary industries are obviously impacted by the transportation network. In the future, to support the integrated development of industries in HHRTS, traffic conditions in each town should be improved appropriately according to the industrial orientation of the town, but excessive investments to construct roads irrespective of eco-environmental impacts and economic benefits should be avoided. Especially in the case of ecologically vulnerable towns, the building high-grade roads should be banned. 相似文献
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基于核密度估计法、最邻近指数分析法以及局域Getis-Ord G*指数法,利用零售商业兴趣点（POI）数据,分析武汉市三个时间节点下的零售商业热点区的空间分布及业态集聚的演变特征,并探讨其驱动机制。研究表明：1）中心城区具有多核发展趋势,远城区低密度点状集聚,商业点由主热点区呈放射型面状扩散;2）武汉市热点区面积与数量增长显著。主次热点13年间由71km2增长到168km2,主热点区由7个增加到10个;3）各零售业态的集聚程度发展具有一定差异性。除医药及医疗器材类业态集聚程度呈降低趋势,其他五类零售业态的聚集程度均有不同程度的提升;4）武汉市零售商业热点区的形成及演变是人地关系互动的结果,区位历史条件、交通网络、政府用地政策、旅游资源开发等多种因素合力影响武汉市零售商业的热点形成及演变。 相似文献
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北京市健身俱乐部多尺度空间格局 总被引：1，自引：0，他引：1
城市健身俱乐部是现代城市游憩空间中的新事物。利用点格局识别和探索性数据分析方法,借助GIS和地统计分析等软件,分析北京市健身俱乐部空间格局特征。最邻近距离系数和样方分析表明,健身俱乐部在全局尺度上存在明显空间聚集,但在行政分区和交通线路分割的单元中,则表现出聚集、随机和离散分布的不同空间格局。1~5km共5个尺度格网单元统计分析进一步验证了健身俱乐部空间格局具有显著尺度效应。样本密度、最邻近距离系数、Moran’s I系数分析发现,样本密度和最邻近距离系数均呈现明显的空间分异和空间自相关,其中2km、3km尺度反映的微观形态特征最为显著。证明全局尺度并非分析健身俱乐部空间格局的唯一和最好尺度,部分微观单元上空间格局将更明显,格局特征也可能会与全局尺度相反。因此多类型、多尺度统计单元能够更全面地反映点要素分布的规律。多尺度空间格局研究,为准确描述城市游憩空间中的点要素空间格局特征,提供了新的研究思路和具体实证。 相似文献
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城市创意旅游资源空间效应及发展模式——以苏州市中心城区为例 总被引：1，自引：0，他引：1
随着创意经济的兴起和旅游者需求的变化,发展创意旅游日益成为消费热点和推动旅游业转型升级的有效途径。创意旅游资源是创意旅游发展的基础,其产生的空间效应是区域旅游研究的重要内容,对提升区域旅游竞争力具有重要意义。以苏州中心城区为例,综合运用最近邻指数、不平衡指数、核密度分析和使用者温度计量模型等方法,深入研究城市创意旅游资源空间效应。结果显示：① 创意旅游资源的融入使苏州中心城区整体和各区域的旅游资源空间分布集聚度增大,但各区域增大程度和资源空间分布状态变化不同;② 融入创意旅游资源后苏州中心城区整体旅游资源区域分布呈集中态势,且分布的均衡度降低;③ 创意旅游资源的融入促进了区域旅游资源空间效应的发挥,苏州中心城区由以姑苏区为“单核心”的“众星拱月”空间格局转变为以姑苏区—工业园区为“双核心”的“日月同辉”空间格局,从而实现苏州中心城区“双核”旅游空间发展模式。 相似文献
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中华老字号企业空间分异及影响因素研究 总被引：1，自引：0，他引：1
以全国1128家中华老字号企业为研究对象,运用平均最邻近指数、核密度分析、不均衡指数、空间自相关分析、热点分析等经济地理分析模型,借助ArcGIS软件,对中华老字号的空间分布密度、区域分异特征、均衡态势、空间自相关性进行了计量分析。在此基础上,就中华老字号的行业类型结构特征进行了系统梳理,并揭示了其空异间分异格局与特征。最后,运用地理联系率、矢量数据缓冲区分析、相关性分析等方法揭示了其内在影响因素。研究发现：① 中华老字号的空间分异呈现2个高密度区、1个次级高密度区和多个高集聚区,核心-边缘结构较为明显,老字号企业主要集中在近现代以来经济基础较好、市场开放程度较高的华北、东部沿海地区,多以沿海开放口岸、省会城市、主干路网为核心,呈寄生状集聚。② 中华老字号企业在空间上并非随机性分布,而是呈现显著的空间自相关性。老字号企业在全国的分布呈现“集聚化,纺锤状”的分异格局,极化现象较为突出。③ 中华老字号企业的冷、热点区由长江中下游平原向南北依次呈现为“热点区-次热点区-次冷点区-冷点区”的梯度分异格局。④ 酒类、医药类、餐饮服务类老字号企业分布呈现“地区集聚化,行业集群化”格局,其他类型老字号企业在全国各地区的分布则呈现“地域均衡化,行业多元化”特征。⑤ 中华老字号的空间分异格局、类型结构特征是资源禀赋与发展基础、地域传统与社会变迁、经济发展与消费市场、文化旅游与消费需求等生产与消费多元因素共同作用及影响的结果。基于此,从中华老字号空间管理、统筹发展、资源要素优化配置、传承创新等方面提出了发展建议。 相似文献
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Catherine Phillips 《The Australian geographer》2017,48(2):169-184
This article draws upon recent geographical work on assemblage to reconsider how we understand alternative food economies. In particular it brings attention to the devices upon which these economies rely—specifically plastics. Since the mid-twentieth century, plastics have developed close and complex relations with our agrifood systems; they facilitate commodity valuation and product circulation worldwide but are also recognised as problematic due to their environmental and human health impacts. Despite this paradox and the attention plastics increasingly receive, we know little of their relations with alternative food initiatives (AFIs). How do plastics inhabit alternative food economies? What associations and circulations become performed? What do these markets look like from a device-oriented perspective? To address these questions, the paper draws on fieldwork undertaken in Brisbane (Australia) with two AFIs—a weekly organic market and an online box program/wholesaler. Using visualisation and an assemblage approach discloses the presences, flows, functions, and tensions of plastics in AFIs. In this way, plastics are revealed but also act to reveal alternative food economies. This analysis steps away from evaluations of AFIs’ (in)effective challenge to neoliberalisation to consider them as complex, processual, sometimes ambivalent efforts that not only distribute ‘good food’ but engage in important ways with things like plastics. 相似文献