Raster data comes from many sources and is the form we generally know from our own digital photography. With Raster data we have a rectangle shape in which each individual point (pixel) is described. The format is x,y,z per pixel. X and Y give the position of the pixel in the raster and z represents the value that belongs to the pixel.
Mostly 'z' represents a color, like in a image, but in a GIS environment 'z' represents a different value. in the case of the DEM the 'z' represents ground hight. When we look at Clutter 'z' could mean the type of clutter that is represented by the pixel.
Disadvantage of raster data is the square size that the pixel represents. The size of the pixel is directly related to the resolution. A high resolution camera at 10 Million pixels produces a better image than a telephone wit 1 million pixel camera. The first one uses a lot more pixels to reproduce the caputered image than the last.
The same is with DEM we know generally 3 resolutions of dem: 1 arc second (30x30 meters) 3 arc second (90x90 meters) and 30 arc second (900x900 meters).
So depending on the zoom level the pixel becomes visual and influences the accuracy of our simulation.
Vector type of data is used in Radio Mobile with DEM, map images, and photo images.