A land surveyor with a total compass, a student with a digital compass in field surveying or land surveying, and an amateurish person who like to do it by himself is the most skilled method, art, science, and profession of measuring the terrestrial or two-dimensional lateral positions and distances between points. If any one of these three (a land surveyor, a student with a digital compass in field surveying or land surveying, and an amateurish person) are unable to determine the exact vertical measurements of any point on earth, he will be able to arrive at only an approximate measurement, a range, or a mean. The range will be wrong and he will also be unqualified to estimate the horizontal distances on which trees or other terrestrial constructions are placed. Therefore, he cannot make any precise estimate for any building construction on earth.
Land surveyors are trained to take precise measurements and then compare them with the true corresponding positions on the real ground through means of instruments such as a degree meter, a hydrograph, a radar, or a laser. They are also trained to take measurements from accurate angles. The hydrograph is a tool used by surveyors to measure elevations and areas of water, whereas the radar is used for more conventional purposes such as determining the positioning of boundaries, identifying a street, determining the boundaries of an island, determining whether a structure is man-made or natural, determining the alignment of a street, etc. A laser has the advantage that it can take very high resolution measurements. Modern surveying instruments also have additional features such as a global positioning system or a global navigation satellite navigation system.
All modern surveying instruments, even the simple theodolites (a little wheel with two pedals that turn like casters) have an incredible capacity to obtain data at extremely high speeds and high accuracy. This high speed allows for more measurements to be made in less time than was possible before. For example, even relatively simple theodolites can register changes of up to 0.6mm during an in-situ measurement, which is much greater than what was previously achievable in the past, as the simple cartograph was often calibrated at one degree. Today, even though the technology is improving all the time, land surveying remains a very important aspect of our day-to-day life. Without it, many of our modern day problems such as traffic congestion, roadworks, flooding, earthquake damage, etc.