Programming Microsoft® SQL Server® 2012

Spatial Models

Let’s begin our discussion with an explanation of the two spatial models. These are known as the planar and geodetic models.

Planar (Flat-Earth) Model

The planar model is a flat surface where shapes are plotted using two-dimensional x- and y-coordinates. The coordinate system semantics are entirely up to you; measurements can be anything from pixels to inches, meters, and miles. It makes sense to work with the planar model when you’re dealing with relatively small areas (such as a piece of paper, building floor plan, or parking lot), 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.

Flattening the earth onto a two-dimensional ...