GIS III

Abstract

The course deals with two advanced topics.The first one consists in methods and techniques for exploring spatial data and computing fields (and maps) from widespread measurements. Exercises are solved with ArcGIS (ESRI).The second is concerned with geographic data and internet (WMS, WFS, GML). We will also create a simple WebGIS by means of the Free and Open Source Software Mapserver (UMN).

Objective

The course deals with two advanced topics in Geographic Information Systems. The first one consists in methodologies and techniques for computing fields from widespread spatial measurements. Many observations are point-wise (i.e.: terrain height, temperature, humidity, pollutant concentration,…) but generally what we need is the corresponding continuous thematic maps. For instance if we have leveling or LIDAR measurements, we could be interested, for many applications (hydrology, ecology, radio and radar propagation, geoscience, landscape planning, terrain-guided navigation systems, ...), in the corresponding land elevation field and its representation, the digital terrain model. In lecturing we will teach how to explore spatial data and how to discriminate (by means of cross-validation techniques) the best method to interpolate them to obtain the best digital model of the corresponding field. In the theoretical part we will mainly focus on deterministic approaches (proximity polygons, local spatial average, inverse-distance-weighted spatial average, global and local polynomial interpolation, radial basis functions). In the last lesson we will present rudiments of stochastic interpolation and simple exercises about this method. All the exercises of this part of the course will be solved by means of the “geostatistical analyst” tool of ArcGIS (ESRI). The second part of the course is concerned with the interaction between geographic data and internet. Most organizations and companies handling spatial data need to publish their own maps. The WebGIS are suited to this purpose. We will teach how to build a simple WebGIS by means of the FOSS (Free and open source software) Mapserver developed at the University of Minnesota. In the last lesson we will see further development in geographic information networking, namely the Web Map and Feature Services. GML and metadata will also be briefly introduced.

Content

Introduction. Exploring spatial data (Histogram, Trend analysis, Variogram cloud, Outlier Detection). Spatial interpolation 1: proximity polygons, the local spatial average, the inverse-distance-weighted spatial average, global and local polynomial interpolation. Crossvalidation and leave-one-out methods to check the results. Spatial interpolation 2: radial basis functions, splines functions with Tykhonov regularization, multiresolution spline functions, kriging. Geographic Information and Internet, WebGIS Services, WMS,WFS, GML and metadata. Commercial WebGISs - The FOSS Mapserver WebGIS. How to build a Mapserver webGIS.

Resources