Spatial Models
Let’s begin our discussion with an explanation of the two basic geospatial models: the planar and model geodetic model.
Planar (Flat-Earth) Model
The planar model is a flat surface where shapes are plotted using two-dimensional x- and y-coordinates. These coordinates are based on an arbitrary measurement system, so you can define any measurement unit you want (for example, centimeters, meters, kilometers, inches, feet, miles, pixels, and so on).
It makes sense to work with the planar model when dealing with relatively small areas (such as building floor plans), or even larger areas that are either conceptually flat or still small enough where the earth’s curvature does not skew the outcome of area and distance calculations. Realize ...
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