![]() Topology brings these objects together into logical groups to form real world models. In a CAD environment, the objects (lines, polylines, points, etc.) have no relationships between them. The primary difference between CAD and GIS is topology. GIS understands connectivity, conductivity, and associativity which enables spatial analysis.GIS understands enclosed areas (polygons) and their associativity with other objects.For instance, the lines describing streets are related to one another. CAD objects don't know about each other, even though they may touch or overlap. using layers, blocks, internal data, and dimensions. ObjectsĬAD objects include lines, circles, arcs, text, etc. Therefore, GIS uses geographic coordinates systems and world map projections while CAD coordinates are relative to the object being modeled and are not usually relative to any particular place on earth. ModellingĬAD models things in the real world. In short, the difference between CAD and GIS is the difference between a drawing and a spatial database. What follows is paraphrased from a portion of his talk.ĪutoCAD Map adds GIS features to the base AutoCAD product and, as such, these features help define the difference between CAD and GIS. At the 1998 Autodesk Design World, Bill Wittreich of Wittreich & Associates, gave a presentation titled Beyond CAD into GIS. ![]()
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