Tacheometry surveying It means the fast measurment of

Tacheometry surveying It means the fast measurment of the distances in both types ( horizantal & vertical ). It is a type of optical distance measurment. �

Tacheometry surveying Advantages of tacheometry surveying : � 1 - Fast measurment of distances. � 2 - More accurate measurment than the ordinary � once & its accuracy from 1500 ---110000. 3 - It can be used in bad conditions of measuring. �

Tangential Method In this method a staff fitted with two targets @ � a fixed distance apart , usually 3 m. Is held @ station and the vertical angles to the two vanes are observed with a theodolite. This method is used when the telescope 0 f the � instrument is not equppeid with astadia diaghram.

Tangential There are 1 -when both Method three cases in this method : � of the observed angles are elevated. � B δ δ � D= ---------- � tan α 1 - tan α 2 � VB C α 1 α 2 A D VC

Tangential 2 -When Method both the observed angles are depression : δ � D =---------- � tan α 1 - tan α 2 � � � α 2 α 1 VC C VB δ B D

Tangential Method 3 - when one of � the obesrved angles is an angle of elevation and the other an angle of depression. B δ � D =------------ � tan α 1 + tan α 2 � V 1 δ α 1 α 2 V 2 A D

Tangential Method sample of field table: � π H. I Target V. angle remarks Staff reading

Test : What are the applications of tangential method ? �

Thank you