共查询到20条相似文献，搜索用时 109 毫秒
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从计算几何的角度提出了一种改进的图斑合并(聚合和融合)方法。图斑聚合采用缓冲区合并的思想,可以有效地合并"桥梁"区域,并保持图斑的自然弯曲形态;图斑融合通过骨架线剖分小图斑,以共享边和地类为共同作用因子,将小图斑逐个合并到原始图斑的拓扑相邻图斑中。此算法有效地维持了图斑边界的自然弯曲,并顾及了图上显示地类的父类整体变化情况。 相似文献
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针对分布式环境下区域分片片段间的各种原始缝隙,提出一种3RM(Three Relational Matrix)缝隙处理模型。该模型采用两阶段流程,第1步划分空间计算单元,对区域分片边界处的要素进行聚类分组;第2步对各个空间计算单元进行缝隙处理。模型研究区域分片边界处缝隙的描述和区分方法,依据要素拓扑关系、属性关系以及精度3种关系建立了3RM缝隙处理矩阵,发现线状和面状要素在分片数据边界处的38种潜在的缝隙,并建立了相应的缝隙处理方法。运用3RM模型对异构的土地利用分片数据进行缝隙处理试验,试验结果表明,本文提出的缝隙处理模型能够有效处理实际分片数据当中的各种缝隙。 相似文献
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图斑面的聚类处理是挖掘图斑空间知识的重要手段。针对当前图斑面大小不一、形态各异、分布不均等导致聚类结果不够准确的问题,同时为满足大规模图斑数据分析的需要,本文引入多密度属性计算指标,提出了一种图斑数据的聚类方法。首先,根据单个图斑内部点位置(包含边界)的不同赋予其多个密度属性;然后,根据图斑间密度低值向密度高值靠拢的趋势建立图斑归属连接,依次生成图斑要素的树状结构连接;最后,依据树状结构连接的结果对各连接进行剪枝或合并,生成多个独立树,完成图斑面的聚类。试验证明,本文方法可以有效识别各类不规则图斑的聚合集群,并在大规模图斑数据的聚合中具有良好的精度表现,满足高密度多边形区域的聚类识别需求。 相似文献
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一种面向海量数字高程模型数据的洪水淹没区快速生成算法 总被引：1，自引：0，他引：1
常见种子点填充算法在实现DEM数据下的洪水淹没区生成时,具有难以处理大数据量以及过多的递归计算易导致算法效率较低等缺点。针对此问题,本文提出一种面向海量DEM数据的洪水淹没区生成算法分块压缩追踪法,该算法采用条带分块和实时栅格压缩存储技术,以解决海量地形数据下的淹没分析计算问题。最后,通过将本算法与常见种子点填充算法和分块种子点填充算法进行了对比测试,实验结果表明本算法不仅较好地解决了海量DEM数据下的洪水淹没区生成问题,与常规种子点填充算法和分块种子点填充算法相比亦具有较高的计算效率。 相似文献
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以东莞市为例,通过土地调查试点工作,提出了线状地物图斑化以及拓扑处理的方法;分析了线状地物图斑化的两种方法和入库技术流程,并针对拓扑问题进行了详细论述,形成了一套全面的试点经验,为全市土地调查工作提供了重要的实践参考。 相似文献
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The extraction of partition lines for long and narrow patches (LN patches) is an important yet difficult problem in the generalization of thematic data. When current methods are used to process polygons with irregular shapes or complex branch convergence zones, the extracted line structural features tend to be inaccurate and topologically erroneous. In this article, we propose an improved partition lines extraction algorithm of constrained Delaunay triangulation to counter these issues. The proposed method aims to maintain consistency between the extracted line structure characteristics and the actual object structure, especially for complex branch convergence zones. First, we describe three types of aggregation patterns (Type A, B, and C aggregation zones) that occur in partition line extractions for LN patches of complex branch convergence zones using Delaunay triangulation. Then, a partition line extraction algorithm that accounts for the direction between the edges of triangles and the distance of nodes in aggregation zones is proposed. Finally, we test our method for a dataset relating to Guizhou Province, China. Compared with the current method that uses quantitative indicators and visualization, the results indicate that our method not only has applicability for simple situations but also is superior for preserving structural features of complex branch convergence zones. 相似文献
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基于GIS和景观生态学的土地整理景观研究 总被引：1，自引：0，他引：1
运用GIS技术和景观生态学理论方法,以安徽省淮南市潘集区市级投资重点土地整理项目为例,选取3类景观指标,对项目区内土地整理前后的土地利用现状和景观格局变化情况进行研究。结果表明： 景观类型中水田斑块占绝对优势,斑块分维数、形状指数呈下降趋势,表明斑块形状趋于规则和简单; 斑块数量和斑块密度降低,平均斑块面积和最大斑块面积增加,最大斑块指数增大,景观破碎度降低; 平均分维数和平均形状指数增大,表明景观形状较整理前变得规则,但总体形态变得复杂; 多样性指数和均匀度指数降低,表明在增加了景观分布均匀程度的同时降低了景观的多样性,景观类型有所减少。 相似文献
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Although traditional cellular automata (CA)‐based models can effectively simulate urban land‐use changes, they typically ignore the spatial evolution of urban patches, due to their use of cell‐based simulation strategies. This research proposes a new patch‐based CA model to incorporate a spatial constraint based on the growth patterns of urban patches into the conventional CA model for reducing the uncertainty of the distribution of simulated new urban patches. In this model, the growth pattern of urban patches is first estimated using a developed indicator that is based on the local variations in existing urban patches. The urban growth is then simulated by integrating the estimated growth pattern and land suitability using a pattern‐calibrated method. In this method, the pattern of new urban patches is gradually calibrated toward the dominant growth pattern through the steps of the CA model. The proposed model is applied to simulate urban growth in the Tehran megalopolitan area during 2000–2006–2012. The results from this model were compared with two common models: cell‐based CA and logistic‐patch CA. The proposed model yields a degree of patch‐level agreement that is 23.4 and 7.5% higher than those of these pre‐existing models, respectively. This reveals that the patch‐based CA model simulates actual development patterns much better than the two other models. 相似文献
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Small‐area patch merging is a common operation in land use data generalization. However, existing research on small‐area patch merging has mainly focused on local compatibility measures, which often lead to area imbalances among land use types from a global perspective. To address the shortcomings of previous studies by resolving local and global concerns simultaneously, this article proposes a merging method that considers both local constraints and the overall area balance. First, a local optimization model that considers three constraints—namely, the areas of neighboring patches, the lengths of shared arcs, and semantic similarity—is established. The areas of small patches are first pre‐allocated. Subsequently, in accordance with an area change threshold for individual land use types, land use types with area changes that exceed this threshold are identified. The patches corresponding to these land use types are subjected to iterative adjustments while considering the overall area balance. Based on their area splitting abilities, the split lines for small‐area patches are determined, and small‐area patches are merged. Finally, actual data from Guangdong Province are used for validation. The experimental results demonstrate that the proposed method is capable of preserving the local compatibility of patches while balancing the overall area associated with each land use type. 相似文献
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Yixiang Tian Markus Gerke George Vosselman Qing Zhu 《ISPRS Journal of Photogrammetry and Remote Sensing》2010,65(4):395-408
The paper presents an automatic method for the reconstruction of building models from video image sequences. These videos may be recorded using a hand-held camera or a camera mounted on a moving car. Such terrestrial video sequences are economic and flexible. Presenting buildings as geometric models–rather than for instance a representation from a simple meshing of 3D points–enables one to perform a wide range of analyses. However, sparse 3D points and 3D edges do not contain topological relations. Therefore, integrating building structure knowledge into the reconstruction steps plays an important role in our method. First, some rules are applied to reasonably group the extracted features. Then, a suitable outline and normal direction are specified for each surface patch. Based on these surface patches, a hybrid model- and data-driven method is used to recover a building model from both the extracted surface patches and hypothesized parts. Using the building structure knowledge leads to a simple and fast reconstruction method, and also enables one to obtain the main structures of buildings. The results show that this method correctly sets up topological relationships between generated surface patches and also obtains reasonable structure models in occluded areas. Therefore, the reconstructed models satisfy requirements for both visualization and analysis. 相似文献
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Rapid urbanization threatens urban green spaces and vegetation, demonstrated by a decrease in connectivity and higher levels of fragmentation. Understanding historic spatial and temporal patterns of such fragmentation is important for habitat and biological conservation, ecosystem management and urban planning. Despite their potential value, Local Indicators of Spatial Autocorrelation (LISA) measures have not been sufficiently exploited in monitoring the spatial and temporal variability in clustering and fragmentation of vegetation patterns in urban areas. LISA statistics are an important structural measure that indicates the presence of outliers, zones of similarity (hot spots) and of dissimilarity (cold spots) at proximate locations, hence they could be used to explicitly capture spatial patterns that are clustered, dispersed or random. In this study, we applied landscape metrics, LISA indices to analyse the temporal variability in clustering and fragmentation patterns of vegetation patches in Harare metropolitan city, Zimbabwe using Landsat series data for 1994, 2001 and 2017. Analysis of landscape metrics showed an increase in the fragmentation of vegetation patches between 1994–2017 as shown by the decrease in mean patch size, an increase in number of patches, edge density and shape complexity of vegetation patches. The study further demonstrates the utility of LISA indices in identifying key hot spot and cold spots. Comparatively, the highly vegetated northern parts of the city were characterised by significantly high positive spatial autocorrelation (p < 0.05) of vegetation patches. Conversely, more dispersed vegetation patches were found in the highly and densely urbanized western, eastern and southern parts of the city. This suggest that with increasing vegetation fragmentation, small and isolated vegetation patches do not spatially cluster but are dispersed geographically. The findings of the study underline the potential of LISA measures as a valuable spatially explicit method for the assessment of spatial clustering and fragmentation of urban vegetation patterns. 相似文献
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按照简单地块的8种拓扑关系分类定义,计算简单地块的拓扑关系。将复合地块的外边界与空洞分离为m＋1个（m是空洞数）简单多边形,分别计算外边界之间、空洞之间、外边界与空洞之间的拓扑关系,并且按照不同的拓扑关系组合,计算复合地块的8种拓扑关系。 相似文献
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基于RS与GIS技术,以2008年甘肃省秦安县SPOT遥感影像为数据源,主要选职斑块面积、斑块数、平均斑块面积、斑块大小变异系数、斑块大小标准偏差、平均形状指数、平均周长．面积比、平均斑块分维数8个景观指数,从居民点用地、规模、形态、分布等方面进行景观空间格局分析。结果表明：秦安县农村居民点分布特点受坡度、坡向、高程、... 相似文献
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Although increased woody plant abundance has been reported in tropical savannas worldwide, techniques for detecting the direction and magnitude of change are mostly based on visual interpretation of historical aerial photography or textural analysis of multi-temporal satellite images. These techniques are prone to human error and do not permit integration of remotely sensed data from diverse sources. Here, we integrate aerial photographs with high spatial resolution satellite imagery and use a discrete wavelet transform to objectively detect the dynamics in bush encroachment at two protected Zimbabwean savanna sites. Based on the recently introduced intensity-dominant scale approach, we test the hypotheses that: (1) the encroachment of woody patches into the surrounding grassland matrix causes a shift in the dominant scale. This shift in the dominant scale can be detected using a discrete wavelet transform regardless of whether aerial photography and satellite data are used; and (2) as the woody patch size stabilises, woody cover tends to increase thereby triggering changes in intensity. The results show that at the first site where tree patches were already established (Lake Chivero Game Reserve), between 1972 and 1984 the dominant scale of woody patches initially increased from 8 m before stabilising at 16 m and 32 m between 1984 and 2012 while the intensity fluctuated during the same period. In contrast, at the second site, which was formely grass-dominated site (Kyle Game Reserve), we observed an unclear dominant scale (1972) which later becomes distinct in 1985, 1996 and 2012. Over the same period, the intensity increased. Our results imply that using our approach we can detect and quantify woody/bush patch dynamics in savanna landscapes. 相似文献