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11.
Jean-Franois Mas Alejandro Velzquez Jos Reyes Díaz-Gallegos Rafael Mayorga-Saucedo Camilo Alcntara Gerardo Bocco Rutilio Castro Tania Fernndez Azucena Prez-Vega 《International Journal of Applied Earth Observation and Geoinformation》2004,5(4):249-261
A nationwide multidate GIS database was generated in order to carry out the quantification and spatial characterization of land use/cover changes (LUCC) in Mexico. Existing cartography on land use/cover at a 1:250,000 scale was revised to select compatible inputs regarding the scale, the classification scheme and the mapping method. Digital maps from three different dates (the late 1970s, 1993 and 2000) were revised, evaluated, corrected and integrated into a GIS database. In order to improve the reliability of the database, an attempt was made to assess the accuracy of the digitalisation procedure and to detect and correct unlikely changes due to thematic errors in the maps. Digital maps were overlaid in order to generate LUCC maps, transition matrices and to calculate rates of conversion. Based upon this database, rates of deforestation between 1976 and 2000 were evaluated as 0.25 and 0.76% per year for temperate and tropical forests, respectively. 相似文献
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Most studies have the achieved rapid and accurate determination of soil organic carbon (SOC) using laboratory spectroscopy; however, it remains difficult to map the spatial distribution of SOC. To predict and map SOC at a regional scale, we obtained fourteen hyperspectral images from the Gaofen-5 (GF-5) satellite and decomposed and reconstructed the original reflectance (OR) and the first derivative reflectance (FDR) using discrete wavelet transform (DWT) at different scales. At these different scales, as inputs, we selected the 3 optimal bands with the highest weight coefficient using principal component analysis and chose the normalized difference index (NDI), ratio index (RI) and difference index (DI) with the strongest correlation with the SOC content using a contour map method. These inputs were then used to build regional-scale SOC prediction models using random forest (RF), support vector machine (SVM) and back-propagation neural network (BPNN) algorithms. The results indicated that: 1) at a low decomposition scale, DWT can effectively eliminate the noise in satellite hyperspectral data, and the FDR combined with DWT can improve the SOC prediction accuracy significantly; 2) the method of selecting inputs using principal component analysis and a contour map can eliminate the redundancy of hyperspectral data while retaining the physical meaning of the inputs. For the model with the highest prediction accuracy, the inputs were all derived from the wavelength range of SOC variations; 3) the differences in prediction accuracy among the different prediction models are small; and 4) the SOC prediction accuracy using hyperspectral satellite data is greatly improved compared with that of previous SOC prediction studies using multispectral satellite data. This study provides a highly robust and accurate method for predicting and mapping regional SOC contents. 相似文献
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《Geoforum》2016
In recent years diverse actors have hailed participatory practice as an effective means to empowering people in payment for ecosystem services (PES) work. In Chiapas, Mexico participation is a central component of the Scolel’ Te carbon forestry program, the cornerstone of which includes Plan Vivo participatory mapping. Plan Vivo mapping is used by the managing NGO, AMBIO, to build trust relations between participating farmers and program managers so as to ensure the successful production of carbon credits. However, I argue that it is also used to instill in farmers a series of behavioral and attitudinal transformations designed to align farmer land-use activities and attitudes with the program’s carbon credit production objectives. Yet, despite these ambitions, the ability of the mapping activity in Scolel’ Te to achieve its stated goals is challenged on the ground. In order to explain this discrepancy between the aspirations tied to the mapping activity and the mapping experience, I assess Plan Vivo mapping as a situated discourse and as a labor process. Taking the former perspective, I show how the managing NGO uses a paternalistic discourse to justify participatory mapping, one that presents farmers as misguided resource managers in need of external intervention. Then, using a labor process approach, I show how PVM acts to reorient farmer relationships to their land and to development organizations by intervening in farmer land-use practices and by establishing trust relations. It is, however, a process that consists of inequalities that stand to potentially limit the effectiveness of the activity. 相似文献
14.
2015年10月26号发射的天绘一号03星是中国传输型立体测绘卫星天绘一号系列的第3颗卫星。三线阵和多光谱影像数据是天绘一号卫星的重要数据,用于立体测绘、彩色融合、遥感观测等多种用途。因此,为了推动天绘一号03卫星影像数据早日为相关领域提供服务,本文采用客观评价的方法,对天绘一号03星的三线阵和多光谱影像质量进行了全面的评价分析。评价结果显示(天绘一号)03星的清晰度、对比度、细节能量、边缘能量、功率谱、信息容量指标值远高于天绘一号01、02星。说明天绘一号03星三线阵/多光谱影像在地物细节和边缘纹理特征的描述上优于天绘一号01、02星,同时载荷接收的信息量远高于天绘一号01、02星。天绘一号03星较高的信噪比指标说明其载荷抑制噪声的能力优于天绘一号01、02星。边缘辐射畸变和增益调整畸变表明在辐射均匀程度上,天绘一号03星三线阵/多光谱影像介于天绘一号01和02星之间。因此,与同类天绘一号01,02星的三线阵与多光谱影像相比,天绘一号03星影像质量有着显著的提高。 相似文献
15.
土地类型系列制图的几个理论问题 总被引:1,自引:0,他引:1
实际存在的不同尺度地域分异规律是土地类型系列制图的客观基础。多种尺度制图构成的土地类型系列制图可以全面揭示区域土地类型的形成因素、分布规律和空间结构特征,也为不同层次土地规划管理之间的相互补充、协调提供了重要基础。 相似文献
16.
多源信息的集成与融合及其在遥感制图中的优化利用 总被引:13,自引:3,他引:13
多源信息的集成和融合是地球信息科学领域的一大热点问题。它的意义和必要性与地球信息本身的特征、采集信息的手段特征及信息处理平台或系统的特点三方面紧密相联系。本文从不同传感器信息的集成和融合、遥感信息与非遥感地学信息的集成和融合、不同格式的 GIS数据的集成和复合三个方面研究了多源信息集成和融合的方法、前沿技术和应用领域,进而以黄土高原土壤侵蚀遥感调查和制图任务为例,介绍了多源信息集成和融合技术在该项目中的优化应用实例,包括技术流程分析、信息源分析、多源信息在土壤侵蚀遥感调查和制图中的融合方法、从遥感图像解译信息到 GIS数据库的转换技术等。 相似文献
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18.
移动式测绘系统(MMS)已在交通管理、城市规划、地图更新、工程勘测、精准农业、战场测绘等领域广泛应用。本文在简要叙述MMS基本概念和主要功能的基础上,探讨了MMS的发展现状和应用方向,进而提出了当前发展MMS需要解决的关键技术,仅供参考。 相似文献
19.
在我国信息化社会的发展进程中,如何通过有效的测绘行政管理,做好测绘为经济建设和我国可持续发展战略的保障和服务是我国测绘事业将要面临的挑战和机遇。本文对我国测绘行政管理体制的发展进行了分析,并结合当前我国测绘行政管理体制的现状与存在的问题,提出了构建适应我国社会发展的、以地理空间信息管理与应用为核心目标的测绘行政体制的思路。 相似文献
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