Automated evaluation of building alignments in generalized maps     

Xiang Zhang  Jantien Stoter  Tinghua Ai  Menno-Jan Kraak  Martien Molenaar 《International journal of geographical information science》2013,27(8):1550-1571

Evaluation is a key step to examine the quality of generalized maps with respect to map requirements. Map generalization facilitates the recognition of pattern generating processes by preserving and highlighting the patterns at smaller scales. This article focuses specifically on the evaluation of building patterns in topographic maps that are generalized from large to mid scales. Currently, there is a lack of knowledge and functionality on automatically evaluating how these patterns are generalized. The issues of the evaluation range from missing formal map requirements on building alignments to missing automated evaluation techniques. This article firstly analyses the requirements (constraints) related to the generalization of building alignments. Then, it focuses on three more specific constraints, i.e. on existence, orientation of alignments and spatial distribution of composing buildings. Later, a three-step approach is proposed to (1) recognize and (2) match alignments from source and generalized datasets and (3) evaluate building alignments in generalized datasets. Besides, many-to-many and partial matching between initial and target alignments is a side effect of generalization, which reduces the reliability of the evaluation results. This article introduces a confidence indicator to document the reliability and to inform intended users (e.g. cartographers) and/or systems about the reliability of evaluation decisions. The effectiveness of our approach is demonstrated by evaluating the alignments in both interactively (manually) generalized maps and automated generalized maps. Finally, we discuss how our approach can be used to control automated generalization and identify further improvements.  相似文献   

Parameterizing canopy resistance using mechanistic and semi‐empirical estimates of hourly evapotranspiration: critical evaluation for irrigated crops in the Mediterranean     

Nader Katerji  Gianfranco Rana  Salim Fahed 《水文研究》2011,25(1):117-129

In this paper two models are presented for calculating the hourly evapotranspiration λE (W m^?2) using the Penman–Monteith equation. These models were tested on four irrigated crops (grass, soya bean, sweet sorghum and vineyard), with heights between 0·1 and 2·2 m at the adult growth stage. In the first model (Katerji N, Perrier A. 1983. Modélisation de l'évapotranspiration réelle ETR d'une parcelle de luzerne : rôle d'un coefficient cultural. Agronomie 3(6): 513–521, KP model), the canopy resistance r_c is parameterized by a semi‐empirical approach. In the second model (Todorovic M. 1999. Single‐layer evapotranspiration model with variable canopy resistance. Journal of Irrigation and Drainage Engineering—ASCE 125: 235–245, TD model), the resistance r_c is parameterized by a mechanistic model. These two approaches are critically analysed with respect to the underlying hypotheses and the limitations of their practical application. In the case of the KP model, the mean slope between measured and calculated values of λE was 1·01 ± 0·6 and the relative correlation coefficients r² ranged between 0·8 and 0·93. The observed differences in slopes, between 0·96 and 1·07, were not associated with the crop height. This model seemed to be applicable to all the crops examined. In the case of the TD model, the observed slope between measured and calculated values of λE for the grass canopy was 0·79. For the other crops, it varied between 1·24 and 1·34. In all the situations examined, the values of r² ranged between 0·73 and 0·92. The TD model underestimated λE in the case of grass and overestimated it in the cases of the other three crops. The under‐ or overestimation of λE in the TD model were due: (i) to some inaccuracies in the theory of this model, (ii) to not taking into account the effect of aerodynamic resistance r_a in the canopy resistance modelling. Therefore, the values of r_c were under‐ or overestimated in consequence of mismatching the crop height. The high value of air vapour pressure deficit also contributed to the overestimation of λE, mainly for the tallest crop. The results clarify aspects of the scientific controversy in the literature about the mechanistic and semi‐empirical approaches for estimating λE. From the practical point of view the results also present ways for identifying the most appropriate approach for the experimental situations encountered. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

地球表层建模研究进展     

岳天祥 《遥感学报》2011,15(6):1111-1130

本文在讨论地球表层概念和地球表层建模定义的基础上,总结分析了地球表面形态表达、地球气候系统模拟、生态系统空间模拟分析和地球表层模拟系统等主要研究进展。分析结果表明,误差问题、多尺度问题、地球表层模拟速度问题和三维实时可视化问题是地球表层建模面临的主要挑战。为了解决这些问题,必须发展和采用诸如以遥感数据为初始场、以地面实测数据为优化控制条件的高精度高速度曲面建模新方法和新思路。  相似文献   

华北平原灌溉需水量时空分布及驱动因素   总被引：9，自引：1，他引：8  

马林  杨艳敏  杨永辉  肖登攀  毕少杰 《遥感学报》2011,15(2):324-339

采用华北平原14个气象站点2002年-2007年的降水资料、76个站点的0-80 cm厚度的土壤参数以及ETWatch系统计算的蒸散发量数据,运用水分平衡原理计算了灌溉需水量的空间分布;利用相关及多元逐步回归分析方法,定量分析了研究区灌溉需水量的主要驱动因素.结果表明:从山前平原到滨海平原,多年平均灌溉需水量分别为28...  相似文献   

河南省夏玉米生长季水分供需时空变化特征   总被引：2，自引：0，他引：2  

李喜平 《干旱气象》2013,(4):796-802

水分条件是制约河南夏玉米高产稳产的重要因素,本文利用河南省夏玉米生长季30个农业气象观测站1961～2011年逐日气象观测资料,计算不同生育阶段夏玉米需水量和水分亏缺量,分析其近50a的水分供需条件时空变化特征。结果表明：夏玉米各生育阶段需水量呈显著的下降趋势;各生育阶段之间水分亏缺量没有显著的年际变化。分析各生育阶段水分供需情况,水分亏缺量为正值表明水分供给不足,为负值表示水分有盈余,出苗一拔节期夏玉米水分亏缺量以负值为主,拔节一抽雄期正负交替各占一半,抽雄一乳熟期和乳熟-成熟期以正值为主。空间分布上,夏玉米各生育阶段需水量与各地海拔高度呈显著负相关,全生育期负相关系数为0．799;各阶段水分亏缺量也有一定的相似性,水分亏缺地区主要分布在豫西和豫西北大部,水分较充足的地区主要分布在漯河、南阳、驻马店等地。  相似文献   

Field water surplus and deficit of major crops in dryland of northern China     

Received date: -- Foundation item: The national key research project: Field water balance  its regulation techniques  water potential productivity  its proper exploitation in typical dryland farming areas of northern China for the Ninth Five 《地理学报(英文版)》2000,(3)

1 IntroductionIn natural conditions, field water surplus or deficit is different between field water requirement and field water supply by nature. Field water requirement can be expressed either as potential field evapotranspiration or as crop water requirement. Potential field evapotranspiration is also called reference crop evapotranspiration which is defined as "the rate of evapotranspiration from an extensive surface of 8 to 15 cm tall, green grass cover of uniform height, actively growing…  相似文献   

Dietary manganese requirement ofP. Vannamei     

Liu Fa-yi  A. L. Lawrence 《中国海洋湖沼学报》1997,15(2):163-167

Graded levels of manganese were supplemented to a semi-purified diet containing 45% crude protein, to provide six levels of manganese (i. e. containing 5, 25, 50, 70, 140 and 210×10⁻⁶, respectively) for two experiments with these experimental diets. The initial weight of shrimp used in the 35–day experiment I was 0.30±0.04 g, and that in the 70–day Experiment II was more than one gram. The results showed that optimum content in the semi-purified diet for the more than 1 gram shrimp ranged from 70 ×10⁻⁶, to 140×10⁻⁶, but supplementation of Mn was not necessary for the small shrimp. Contribution No. 2673 from the Institute of Oceanology, Chinese Academy of Sciences.  相似文献   

STUDIES ON THE PHOSPHORUS REQUIREMENT AND PROPER CALCIUM/PHOSPHORUS RATIO IN THE DIET OF THE BLACK SEA BREAM(SPARUS MACROCEPHALUS)     

刘镜恪  李茂堂  王可玲  王新成  刘建康 《中国海洋湖沼学报》1993,(2)

An experiment on the phosphorus requirement and the proper Ca/P ratio in the diet of the black sea bream using the phosphorus gradient method (with casein as basic diet, sodium dihydrogen phosphate as source of phosphorus, and calcium lactate as source of calcium) showed that growth was greatly affected by the diet's phosphorus content and Ca/P ratio. Inadequate phosphorus in the diet resulted in slow growth and poor food conversion ratio (FCR). Analyses of the fish body showed it contained a high level of lipid but a low level of moisture, ash, calcium and phosphorus. The optimal values of phosphorus and Ca/P ratio in the black sea bream diet are 0.68% and 1:2 respectively. Phosphorus in excess of this optimum value resulted in slow growth or even death. The results of this experiment clearly indicated that phosphorus is the principal mineral additive affecting black sea bream growth.  相似文献   

关于设立“张衡计划”的建议——为中国地球物理仪器研发和产业化   总被引：9，自引：4，他引：5       下载免费PDF全文

滕吉文 《地球物理学进展》2009,24(4):1155-1166

地球物理学在本质上是一门观测科学,高精度、高分辨率的观测和实验仪器、设备是地球物理学发展进程中的“前哨”.为此,本建议对中国的地球物理科学仪器事业的现状和未来发展方向进行了讨论,提出了一些论点、论据和想法与建议.对中国地球物理现代化仪器与设备的研发进程进行了历史回顾和剖析,对发展自主创新的地球物理科学仪器事业的战略地位进行了细致的思考;对依赖国外科学技术的危害性进行了深刻的讨论;对中国地球物理科学仪器事业的现状进行了理智的分析;对中国地球物理仪器和设备研制队伍从有到无的缘由进行了深度剖析;为此,提出了要使中国地球物理事业得到健康迅速发展,必须国家统一规划和统一管理的国家行为的思想,提出了设立“地球物理仪器设备研发工程”——“张衡计划”的建议,并对不同阶段性发展的具体目标、任务和实施给予了框架性的厘定.为此,中国地球物理科学仪器与设备事业,当今必须转变观念,依据国家战略需求和自主创新的理念,创自己的品牌,并逐步产业化,乃是进入世界地球科学强国的根本.  相似文献   

新疆三工河流域农业需水量预测与分析   总被引：2，自引：1，他引：1  

占车生  丰华丽  马灵玲  姜小光  王飞 《干旱区地理》2009,32(3)

依据新疆三工河流域的农业生产发展情况以及农业用水现状,综合考虑该流域土地资源状况和农业发展方向,结合国家西部大开发战略和相关的宏观经济调整政策,预测2005年、2010年和2020年流域三个水平年的农业需水量,分析了未来20年的农业需水态势.同时,结合该地区工业、生活、生态环境需水量的未来变化趋势,平衡分析了在满足未来农业需水条件下的社会-经济-生态复合系统水资源配置的合理性,并提出从农业灌溉中节水,尽量追求内涵式发展的农业模式,这才是谋求三工河流域社会-经济-生态复合系统可持续发展的有效之路.同时,这也为国家对该地区的国土开发、经济建设布局以及长远水资源利用问题进行宏观决策提供了参考依据.  相似文献