Display and Measurement from Digitized Stream Centerline Data

Maps are an effective method for conveying spatially distributed information; increased effectiveness is realized when maps are the product of a computer system. Decisions made at the outset of implementing an information system have important effects on costs of creating and using the cartographic component of the system. The purpose of this paper is to discuss and to evaluate procedures for the capture, storage, retrieval, measurement, and display of line data for use in the Illinois Streams Information System. Based on the results of experiments designed to test the utility of different techniques for displaying stream data, fractal enhancement of low resolution stream centerline data has been shown to be adequate for thematic mapping. The required data are already available in machine readable form and thus data capture problems and costs are circumvented. The use of low resolution data also implies that decreased storage and retrieval costs will be realized. Length measurements derived from digital files are unnecessary at this time, further increasing the attractiveness of using low resolution data.