Pre-Engineering or Topographic surveys develop a picture of what a site looks like today. These are often performed prior to design and construction for the development of a site. Each of these surveys are custom tailored to what the clients needs are.
Typical features would include things like asphalt edges, road centrelines, curbs and sidewalks, storm and sanitary sewer structures, power and communications services, buildings, etc.
Often the surface of the ground is represented as a Digital Terrain Model (DTM). This is a computer generated model that represents the surface of the ground and allows calculations to be performed and potential development options to be assessed relative to where the ground is today. This is important for things like balancing cuts and fills (making sure there is not a need to import or export large volumes of earth to or from the site), assessing suitability and build-ability of design relative to existing site constraints such as existing roads, buildings, or other infrastructure.