How is surface information typically stored in a GIS?

Surface information in a Geographic Information System (GIS) is typically stored as cell values or triangulated 3D networks because these methods accurately represent the continuous variation in terrain and other physical features across a landscape.

When utilizing cell values, also known as raster data, the surface is divided into a grid of cells, each containing a value that represents a particular attribute of that area (such as elevation). This format is particularly useful for representing phenomena that change continuously, such as temperature, precipitation, or elevation, as it allows for easier analysis and visualization through various techniques like interpolation or surface modeling.

Triangulated 3D networks (TINs) offer another method of representing surface information by creating a network of triangles from a set of points representing the surface. This method captures the complexities of the landscape efficiently, especially in areas with variable terrain, as each triangle can adapt to the local surface slope and aspect.

Both of these methods provide a more practical and dynamic way to understand and analyze surface characteristics than just storing data as vector roads or geographic coordinates, which do not inherently convey surface continuity or variation.