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Comparing GIS TO CAD & Automated Cartography
COMPUTER AIDED DRAFTING/DESIGN (CAD) CAD systems are a graphic system, meaning they are designed to handle geographic features as separate layers for retrieval and display only. A main drawback is that they do not link a database of feature attributes to the geographical points nor perform user-defined analytical tasks. CAD systems, for example, cannot automatically highlight features of the coverage that share a common attribute from a common database. AUTOMATED CARTOGRAPHY Links a database to a pictorial representation of geographical space. They are restricted to data retrieval, classification and symbolization, not unlike an electronic filing cabinet. The user can retrieve graphics that answer only those questions already asked and previously encoded for retrieval by the database manager. Even the most sophisticated AC system cannot take the next step and provide answers to a range of relevant questions that could be asked about the data, but haven’t yet. GIS A GIS is a decision-support system that integrates spatially referenced data in a problem-solving environment (DJ Cowen, 1995). It automatically synthesizes existing layers of geographic data, from maps to remote sensing images, and updates a database based on new or revised data inputs. Whereas the map output is the most important product for CAD or AC users, it is often only a convenient by-product for GIS users interested in resource management or analysis questions. Often a new data table or elevation model will be the crucial output goal. |