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NEW DATA SOURCES

The generation of data from new sources is an on going development. Application specialists have traditionally attempted to research and implement new data sources into their work. Most of these new data sources are based strictly on scientific technological developments.

Remote sensing will become, if it is not already, the primary source for new data. Due to recent technological developments in hardware most GIS software can now accommodate remotely sensed imagery at high resolutions, and in varying formats. Remote sensing data can include aerial photographs, satellite imagery, radar imagery, etc. Some of the past problems with using remotely sensed imagery have been the inability to integrate it with other data layers, particularly vector encoded data. Remote sensing specialists stress that their data is of most value when combined with, and substantiated by, other data sources. Several commercial GIS products are now offering their software bundled with an image processing software package. Many of these packages allow you to interactively view data from both systems simultaneously, and also afford the conversion of data between systems. The integration of GIS and image processing capabilities offers a great potential for resource specialists.

Another data source that has generated much interest is Digital Elevation Models (DEM). Elevation data has traditionally been generated from the interpolation of contour information. However, recent technological developments and the establishment of several digital mapping projects by government agencies has propagated the use of and interest in elevation modelling. Several different sources of DEM data exist within Canada. The most common and readily available DEM data can be acquired from either the federal government, e.g. 1:250,000 map scale, or from selected provincial government agencies. For example, DEM data commensurate with a 1:20,000 map scale is distributed by the Alberta Government under the 1:20,000 Provincial Digital Mapping project. In British Columbia, DEM data is available with the 1:20,000 TRIM project. In both these cases DEM data is captured photogrammetrically during the stereo-compilation phase of the topographic data capture process. Each DEM is comprised of X,Y, and Z coordinates at regular intervals across a map sheet. This regular grid is supplemented by spot height data points and breakline information (irregular points). In the United States, DEM data is available from a variety of sources, however the most common is the USGS (United States Geological Survey) 1:24,000 QUAD sheets.

DEM data can be used in the generation of a variety of data derivatives. The most common are slope and aspect. The ability to integrate DEM data is a common function within most GIS packages. However, it is typically offered as a separate module that must be purchased individually.