The three different methods to measure linear distances is the Direct measurement method, measurement by Optical means and Electro-magnetic methods. The merit of each method is dependent on the accuracy of the values provided by each method. We will look into the classification of each method by the help of a flowchart given below.
 

Direct Measurement Method

The various methods involved in measuring the linear distance directly are: 
  1. Pacing 
  2. Measurement with Passometer 
  3. Measurement with Pedometer
  4. Measurement by Odometer and Speedometer 
  5. Chaining 

Measurement by Optical Methods 


The measurement of linear distance by optical means is performed through Tacheometric Surveying.

Measurement by Electro Magnetic Methods


The measurement of linear distance by electromagnetic methods is performed by Electro-magnetic distance measurement (EDM)