Mapping with Drupal

Data Storage

There are a number of open source and proprietary storage systems for geospatial data, and there are just as many standards for how to represent the data. We will go through some of the basics here, but this is a large topic that we cannot cover completely. The Open Geospatial Consortium (OGC) is a well-established body that helps define many of the open standards used in geographic information systems. It is helpful to understand these concepts as you decide on the best way to gather and store information to display on your map.

Data Types

There are two main data types when talking about geospatial data: vector (such as points and lines) and raster (such as satellite imagery).

Vector data

Most often, geospatial data is represented as geometric shapes and stored sets of numbers representing these shapes; these are most commonly points, lines, or polygons.

Vector data standards

Three of the main geographic data storage types are shown in the table below (Table 2-1) for point data and polygon data (a shape), along with a text version. When we think about a place, typically we refer to its name, for example, New York. But this is not very useful when we try to do calculations or comparisons. What do we mean when we say New York? Are we talking about the city? The state? The borough of Manhattan? And nothing in the names Shanghai and Sydney is any help in determining where they are or what the distance is between them. Representing a location with numbers (for example latitude ...