text: how do you survey?   surveying is the mapping of the land surface in three dimensions.  usually a grid is set up in the area of interest.  a person with a surveying scope measures the distance to a target which the 2nd person in the surveying team is holding at a specific point on the grid.  they determine the distance between the points and the angle of elevation which can be used later to calculate the 3 d position of the point.  the very first point on the survey is the reference point, and all other measurements refer back to that one point.  they continue to take measurements at the intersection of the lines of the grid, and end up plotting these points with computer programs.    road surveying, however, may not focus on grid points, but be specific points on the road itself.  they may need to determine where the on ramp precisely intersects the higway, or where bridge pilings are, etc.  these intense feature-driven surveys are usually needed to scope out areas for new construction or modifications to existing construction.  topographical maps are 2 dimensional plots of points with different heights.  if you connect a dot between all the points with the same heights, you can visualize mountains and depressions on a 2d paper, and find out where flood zones are and which way water will flow.    check out the usgs for explanations of maps and cartography, etc.  the basics are a linear measuring tape, a surveying scope to determine angles of elevation, and a second person to hold the target.  hope this helps!!