纪伊半岛地区植被净初级生产力的遥感应用研究

在高光谱数据模式分解方法(PDM)的基础上,建立了一种新的植被指数(VIPD)。根据地面植被光合成实验,建立了有效光合成曲线植被净初级生产力(NPP)遥感估算模型,利用2001年各月份的MODIS影像数据,估算得到纪伊半岛地区的各类NPP。研究发现,该地区的温带常绿林NPP年均值与2001年IPCC调查报告和地面实测得到的估算值在误差范围内一致。实验证明,该光合成曲线NPP估算模型能够有效地利用高光谱数据,且能较好地应用于温带植被研究。     

地理信息系统的演进与发展

分析了地理信息系统产生和发展的背景、地理信息系统软件体系结构和开发模式的发展变化,并基于开放的思想提出地理信息系统将向以网络服务和网格服务为主要形式的开放式GIS方向发展,以实现地理信息的共享与空间数据互操作以及信息资源共享与协同解决问题.     

Regional yield estimation for winter wheat with MODIS-NDVI data in Shandong, China

The significance of crop yield estimation is well known in agricultural management and policy development at regional and national levels. The primary objective of this study was to test the suitability of the method, depending on predicted crop production, to estimate crop yield with a MODIS-NDVI-based model on a regional scale. In this paper, MODIS-NDVI data, with a 250 m resolution, was used to estimate the winter wheat (Triticum aestivum L.) yield in one of the main winter-wheat-growing regions. Our study region is located in Jining, Shandong Province. In order to improve the quality of remote sensing data and the accuracy of yield prediction, especially to eliminate the cloud-contaminated data and abnormal data in the MODIS-NDVI series, the Savitzky–Golay filter was applied to smooth the 10-day NDVI data. The spatial accumulation of NDVI at the county level was used to test its relationship with winter wheat production in the study area. A linear regressive relationship between the spatial accumulation of NDVI and the production of winter wheat was established using a stepwise regression method. The average yield was derived from predicted production divided by the growing acreage of winter wheat on a county level. Finally, the results were validated by the ground survey data, and the errors were compared with the errors of agro-climate models. The results showed that the relative errors of the predicted yield using MODIS-NDVI are between −4.62% and 5.40% and that whole RMSE was 214.16 kg ha⁻¹ lower than the RMSE (233.35 kg ha⁻¹) of agro-climate models in this study region. A good predicted yield data of winter wheat could be got about 40 days ahead of harvest time, i.e. at the booting-heading stage of winter wheat. The method suggested in this paper was good for predicting regional winter wheat production and yield estimation.     

Laser Scanning的基本原理及其应用前景

首先介绍了激光测距仪的发展历程,针对应用领域的不同,分别对3维激光成像仪和机载/星载激光测高仪的测量原理进行了阐述,并分别介绍了两种激光测距仪的工作流程以及数据处理流程,最后对两种激光测距仪的应用范围进行了阐述,并把两种激光测距技术和普通摄影测量进行了比较,指出了激光测距技术相对于普通摄影测量的优点,即高精度性、穿透性、实时性。     

海图出版数据更新技术研究

本文在分析了海图更新源数据和我国海图出版数据特点的基础上,深入研究了利用海图更新源数据实现海图出版数据在服务器端交互式更新和在客户端自动更新的关键技术,并具体探讨了在MicroStation V8系统平台下,通过二次开发的途径实现海图出版数据更新的思路与方法。     

用多种策略从机载Lidar数据中提取建筑脚点

设计了一种采用多种策略的建筑脚点提取方法,针对建筑脚点提取中的两个关键步骤———数据分类和建筑脚点分割,分别提出和引入了邻近关系和r半径点密度,从仅反映单次反射的DSM数据中,直接提取出建筑表面点。     

Road Surface Modeling and Representation from Point Cloud Based on Fuzzy Clustering

A scheme for an automatic road surface modeling from a noisy point cloud is presented. The normal vectors of the point cloud are estimated by distance-weighted fitting of local plane. Then, an automati...     

VR-GIS技术在高压输电线选线中的应用研究——以康定-崇州500kv送电线路为例

VR-GIS技术是一门新兴技术,已经在很多领域得到广泛应用。本文基于ERDAS、ArcGIS、MapGIS等遥感和GIS专业软件,将VR-GIS技术应用到高压输电线选线中,制作康定-崇州500kv送电线路(大杠～沙坪段)走廊带的三维景观飞行模拟系统,再现研究区真实地形、地貌,使工作人员沉浸于虚拟环境中,为其分析和处理问题提供方便,解决因自然环境恶劣造成的外业调查困难等问题。     

Transmission and visualization of large geographical maps

Transmission and visualization of large geographical maps have become a challenging research issue in GIS applications. This paper presents an efficient and robust way to simplify large geographical maps using frame buffers and Voronoi diagrams. The topological relationships are kept during the simplification by removing the Voronoi diagram’s self-overlapped regions. With the simplified vector maps, we establish different levels of detail (LOD) models of these maps. Then we introduce a client/server architecture which integrates our out-of-core algorithm, progressive transmission and rendering scheme based on computer graphics hardware. The architecture allows the viewers to view different regions interactively at different LODs on the network. Experimental results show that our proposed scheme provides an effective way for powerful transmission and manipulation of large maps.     

模糊综合评判方法在桥梁索塔变形中的应用

桥梁索塔的安全监测体系作用重大,关系着索塔投入使用的安全性.由于产生变形的因素众多,很难构建严格的函数关系模型.而采用模糊数学中的多层次模糊综合评判方法能够较为准确地分析索塔顶部点位是否变形.针对某大型跨江大桥索塔顶部的点位变形量进行综合评判,选取6个影响因子作为索塔顶部某点变形量的主要关联因子,通过计算获得了较为真实...