Understanding raster data

…The other popular method of storing geospatial…data is through a process called rasterization.…Raster data is a grid of cells organized into columns and rows called pixels.…Each cell can hold a single color or value which…can represent all kinds of information, from the color of light…that are reflected off the surface, or an elevation above…sea level, or how many inches of rain fell in January.…And as you stack these cells together into a large gridded surface,…they cover an area of the earth, just like a giant chessboard.…The most common raster formats that you will work with is an areal photograph.…

And they're exactly what you expect them to be.…Photographs of the earth taken from a satellite or an aircraft.…Aerial images go through a process called orthorectification, which…eliminates most of the distortion that comes with the…perspective and camera lenses and tags the image with…location attributes, so that it correctly aligns on the GIS.…The grid of cells each represents an area of the earth's surface,…