TerraEx – a GeoWeb app for world-wide content-based search and distribution of elevation and landforms data

Abstract

GIScience 2016 Short Paper Proceedings TerraEx – a GeoWeb app for world-wide content-based search and distribution of elevation and landforms data P. Netzel 1 , J. Jasiewicz 1,2 , T. F. Stepinski 1 Space Infromatics Lab, University of Cincinnati, 401 Braunstein Hall, Cincinnati, OH 45221-0131, US Email: {netzelpl; stepintz}@mail.uc.edu Instititute of Geoecology and Geoinformation, Adam Mickiewicz University, Dziegielowa 27, Poznan, Poland Email: jarekj@amu.edu.pl Abstract Terrain Explorer (TerraEx) is the first world-wide content-based search application for landscapes. Using 3 resolution world-wide DEM as an input it finds and displays, in the form of a similarity map, locations in the world where landscapes are similar to a user-selected query. TerraEx is a freely available, full service GeoWeb application. It also doubles as the most convenient distributor of global 3 DEM data, the global map of geomorphons, and the global map of terrain relief. TerraEx opens a possibility to utilize publicly available DEM archives in their entireties for world-wide exploration through content-based search. 1. Introduction Digital Elevation Model (DEM) is one of the most useful data types in geosciences with applications in multiple disciplines from geomorphology through civil engineering to virtual reality and entertainment. Popularity and broad adoption of DEMs follows in part from the fact that medium and low resolution DEMs are freely available for download; examples include the Shuttle Radar Topography Mission (SRTM) world-wide DEM and US-wide National Elevation Dataset (NED). Users can access DEMs by selected region, coordinates, or administrative regions. However, until now, these vast resources could not be explored in their entirety due to the lack of search tools for content-based retrieval of topographic information. In this paper we report on development of Terrain Explorer (TerraEx) – the first application for content-based retrieval of topographic information. TerraEx is a GeoWeb application (http://sil.uc.edu/webapps/terraex) that enables the world-wide search for topographic landscapes similar to a user-selected query landscape. It uses a world-wide 3 (90m) DEM (see next section for details) for elevation data. The search is not performed directly on the DEM; instead it is performed on the DEM classified into the ten landform elements using the geomorphon method (Jasiewicz and Stepinski 2013a). TerraEx also doubles as the most convenient source of world- wide, geographically registered topographic data. A user can navigate to a location of interest (with or without a prior exploration using the search) and download (in GeoTIFF format) a 3 resolution DEM, a map of geomorphons, and a map of terrain relief. In the process of constructing TerraEx we developed the following new products and concepts: (a) a new, adaptively smoothed version of world-wide, 3 DEM that removes artifacts in the flat areas, and (b) a methodology for comparison of spatial patterns in a globe geometry