Tuesday, 7 August 2018

Plotting Detail




Plotting Detail: Offset Scale.

Scale: It is not always possible to represent the actual length of an object on a drawing. So, it is required to reduce the object in order to accommodate it on the drawing, in some portion. The ratio by which the actual length of the object is reduced or increased is known as the ‘scale’.

  Full-Size Scale- If the actual length of the objects is shown on the drawing, the scale used is said to be a full-size scale.

  Reducing Scale - If the actual length of the objects is reduced in order to accommodate it in the drawing sheet, the scale used is said to be a reducing scale.

  Increasing or Enlarging Scale - If the actual length of the objects is enlarged so as to bring out its details more clearly on the drawing, the scale used is said to be an enlarging scale.

Representative Fraction (RF): The ratio of the distance on the drawing to the corresponding actual length of object is known as the representative fraction, i.e.

        Distance on the drawing of object  
RF = ---------------------------------------Corresponding actual distance of object

         (Both distance in same unit.)                                                 
Conversional Symbols

  In a map the objects are shown by symbols and not by name. so the surveyor should know the following standard conventional for some common objects.
 















(Next post on “Procedure of plotting”)


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