GIS is a cyclical rather than a linear system, unlike computer aided drafting (CAD) and computer assisted cartographic systems. Changes in projection, grid systems, data forms, and formats take place during the modeling process for which GIS was designed. Many non-analytical manipulations are necessary to accommodate the analytical power of the GIS. The manipulations of spatial and spatio-temporal data involve two general classes of operation: 1. Their transformation into formats that facilitate subsequent analysis (see this Unit AM13), 2. Generalization and aggregation that affect the accuracy and integrity of the data used for analysis (see Unit AM14) Other knowledge areas have identified different forms of data structures, data models, projections, and other forms of geospatial data representation. These differences present both opportunities and challenges for analysis and modeling. The ability to transform one representation to another, in a manner that maintains the integrity of the information as much as possible, can enhance the analysis and visualization of geospatial data. The raster and vector data models are described in Units DM3 Tesselation data models and DM4 Vector and object data models. The principles of coordinate systems, datums, and projections are also considered in Knowledge Area GD: Geospatial Data
Explain in which cases representation transformation is needed.
In progress (GI-N2K)