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. �

Tacheometry surveying Types of instruments were used : � 1 - Level & staff. � 2 - Theodolite & staff. � 3 - Alidade with plane table & staff. � 4 - Reduced tacheometry & staff. � 5 - Subtense bar with theodolite. �

Tacheometry surveying Stadia method : � This type of tacheometer dependes on the stadia hairs which can be seen on the diaghram. There two cases in measuring : � 1 - horizontal telescope : � D= K * S + C � D : measure distance � S : stadia interval = upper reading - lower reading � K: stadia interval factor = 100 � C: stadia constant = 0. 0 � �

Stadia method 2 - Inclined telescope: � 2 � H = K* S * cos (α ) � V = (12 ) * K * S * sin ( 2α ) � H : horizantal distance. � V : vertical distance � α : vertical angle �

Stadia method π H. I Staff station Vertical angle Staff rading U M L H. distance V. distance

Stadia method Difference in elavation between two stations � There are three cases : � B 1 - Tow V. angles are elevated � αa αb VA RR A A EL. A + RR. A- VA + RR. B = EL. B � RRB vb

Difference in elavation between two stations 2 - One V. angle is elevated another is depression. � VA RR. A A αA αB V B RR. B EL. A+ RR. A- VA-VB –RR. B = EL. B � B

Difference in elavation between two stations 3 - Tow V. angles are depressions. � VA αA αB V B RR. A A EL. A +RR. A +V. A – V. B –RR. B = EL. B � RR. B B

test : State with the sketch how to calculate the � difference in elevation between tow stations by stadia method ?

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