Surveying

Unit: - 9     Measurement error and accuracy The difference between a measured value and the true value is known as true error. The true error cannot be determined as the true value is never known. However, using the theory of probability, it is possible to determine a value called the most probable value which is close to the true value. The most probable error and the standard error can also be determined. A discrepancy is the difference between two measured values of the same quantity, it is not an error. A discrepancy may be small, yet the error may be great if each of the two measurements contains errors that may be larger. It does not reveal the magnitude of systematic error.  Significant figure and rules: In surveying, an indication of accuracy attained is shown by number of significant figures. Each such quantity, expressed in n number of digit in which n-1 are the digit of definite value while the last digit is the least accurate digit which can be estimated and is su

Map Reading UNIT: 8 Map Reading Maps are the symbolic representations of an area, usually drawn on a flat surface. They present information about the world in a simple, visual way, teaching us about the world by showing the sizes and shapes of countries, locations of features, and distances between places. Map ·          A map is a depiction or sketch of the earth’s surface or a portion of it rendered on a flat surface to scale ·          Maps provide a detailed depiction of a larger section of the globe ·          The plan is termed a map if the size of the graphical depiction on a horizontal plane is modest ·          For a small-scale reference, the map is created ·          Vertical distances like elevations are also indicated on a topographic map by contour lines ·          A map is created for big areas like the Map of the Region. Types of Maps: 1.     On the basis of purpose: a.      Topographical map b.     Cadastral map c.      Thematic map d.