Developing spatially and thematically detailed backdated maps for land cover studies

Global or regional land cover change on a decadal time scale can be studied at a high level of detail using the availability of remote sensing data such as that provided by Landsat.However,there are three main technical challenges in this goal.First,the generation of land cover maps without reference data is problematic(backdating).Second,it is important to maintain high accuracies in land cover change map products,requiring a reasonably rich legend within each map.Third,a high level of automation is necessary to aid the management of large volumes of data.This paper describes a robust methodology for processing time series of satellite data over large spatial areas.The methodology includes a retrospective analysis used for the generation of training and test data for historical periods lacking reference information.This methodology was developed in the context of research on global change in the Iberian Peninsula.In this study we selected two scenes covering geographic regions that are representative of the Iberian Peninsula.For each scene,we present the results of two classifications(1985-1989 and 2000-2004 quinquennia),each with a legend of 13 categories.An overall accuracy of over 92%was obtained for all 4 maps.

Building the World Wide Hypermap(WWH)with a RESTful architecture

The hypermap concept was introduced in 1992 as a way to hyperlink geospatial features to text,multimedia or other geospatial features.Since then,the concept has been used in several applications,although it has been found to have some limitations.On the other hand,Spatial Data Infrastructures(SDIs)adopt diverse and heterogeneous service oriented architectures(SOAs).They are developed by different standard bodies and are generally disconnected from mass market web solutions.This work expands the hypermap concept to overcome its limitations and harmonise it with geospatial resource oriented architecture(ROA),connecting it to the semantic web and generalising it to the World Wide Hypermap(WWH)as a tool for building a single‘Digital Earth’.Global identifiers,dynamic links,link purposes and resource management capabilities are introduced as a solution that orchestrates data,metadata and data access services in a homogeneous way.This is achieved by providing a set of rules using the current Internet paradigm formalised in the REpresentational State Transfer(REST)architecture and combining it with existing Open Geospatial Consortium(OGC)and International Organization for Standardization(ISO)standards.A reference implementation is also presented and the strategies needed to implement the WWH,which mainly consist in a set of additions to current Geographic Information System(GIS)products and a RESTful server that mediates between the Internet and the local GIS applications.