5 - Geographic data collection

Abstract

In developing maps or in conducting spatial analyses that support natural resource management activities, one needs geographic information system (GIS) databases. Often, these databases may need to be created by the person making the map or conducting spatial analyses. Alternatively, GIS databases may be acquired from public or private sources and simply used to make maps or incorporated into analyses without alteration. In developing GIS databases, one could digitize vector features (point, lines, polygons) from maps or aerial images, create vector features using location data from global positioning systems (GPS) or raster image processing algorithms, and import coordinates related to vector features directly into GIS software. Vector features can be created directly from stereo-compilers, scanners can be used to convert printed maps or aerial images to raster GIS databases, and aerial systems can also be used to directly capture vector or raster data. As the topics in this chapter suggest, there are a number of options available today to create GIS databases. The accuracy desired, the costs incurred, the time needed, and the feasibility of creating a GIS database will influence the course one takes to gather the data needed.