Raster Data Structures
In Chapter 2, we saw that using a raster GIS we could store a set of spatial data in the form of a grid of pixels. Each pixel will hold a value which relates to some feature of interest at that point in space. In fact, there are two main types of raster layer which are used in GIS:
- Raster imagery. These days we are surrounded by imagery in digital format - modern televisions and computers all have screens in which the picture is composed of pixels and the photographs we all take on our cameras and phones are in a raster format. We are also used to seeing maps and satellite images used on web pages and even on phones. In all these cases, what is stored is a raster grid of colours, coded in some numerical fashion. ...