Methods of Levelling: 1. Height of Collimation Method 2. Rise and Fall Method 1. Collimation Method: It consist of finding the elevation of the plane of collimation ( H.I.) for every set up of the instrument, and then obtaining the reduced level of point with reference to the respective plane of collimation. 1. As can be seen on Fig 1., where practicable we kept our sights to the magnitude of 20-25m to reduce collimation error, with an IS on a memorable location between these two CPs. Each of us took turns to read the level, book the results and hold the staff. Results. Fig 1 showing the location of our survey stations, change points and intermediate sights. Mar 31, 2010 · This tells you nothing about the quality of the measurements. For that, you need to compare the calculated final reduced level with the known final reduced level. With a levelling survey, you always start on a known height and finish on a known height, in order to check for cumulative errors in the measurements.

16 Now add the reduced height and the correction to give you the final height 17 Subtract the first final height from the last reduced height. This must equal ΣBS -ΣFS and ΣRise - ΣFall as check Check Rise and Fall method to reduce a leveling field book page written By Rolita Rode There are two methods of booking levels: Collimation Method: (The height of collimation is the height of the horizontal line of sight above the datum, and is sometimes called the height of instrument). In order to understand this you should watch the ‘Calculating the Height of Collimation’ video on the left hand column. Rise and Fall Method