1. Types of angles A Z MLN – Horizontal angle ALM – Vertical angle
NLB – Vertical angle
ZLA – Zenith angle
ZLB – Zenith angle M L R N B

2. The theodolite Measure: vertical and horizontal angles
Main components - sighting telescope, horizontal and vertical circles and leveling system.
Horizontal (Trunian) axis
Line of sight
Vertical axis
Axis of plate level

4. In a well condition theodolite
1- Line of sight axis + H-H axis
2-H-H axis + V-V axis
3- V-V axis + L-L axis
If these axis are not perfectly perpendicular , errors in angles will occur
To reduce these errors the mean of the face left and face right reading is taken

6. Types of theodolite 1- Optical reading theodolite
2- Digital reading theodolite
The total station : Digital reading theodolite
+EDM( electronic distance measurement device )
+ processor and memory

8. Major Components of a theodolite
Telescope
Vertical circle+ horizontal circle
Horizontal/vertical clamp
Horizontal/vertical slow motion screws
Plate bubble (Level tube)

9. Optical reading theodolite

10. Setting up a theodolite
Centering
Levelling
Elimination of parallax
Sighting the target
Reading the angle

11. Measuring horizontal angles
Sight point A on face left
Set reading on horizontal circle ( e.g. 00 00´ 00˝)
Direct the telescope to point B and record ‘face left’ directions (e.g. 35 26´ 20˝)
Reverse the telescope to ‘face right’ and read direction to point B ( 215 ˝)
Back to point A on face right and record the reading ( )

12. Station at Station observed Face left Face Right
In the figure, the horizontal angle was measured at B to C and A. Compute the angle CBA.
Station at Station observed Face left Face Right
deg min sec deg min sec
B C A A B C

13. Errors in Angle Measurement
Mistakes –pointing, setting up over the wrong point, booking, reading
Random – settling of tripod, wind, temperature, refraction
Systematic/instrumental
Horizontal axis not perpendicular to the vertical axis
Axis of sight not perpendicular to the horizontal axis
Axis of the plate bubble not perpendicular to the vertical axis.

14. Total station ZA (Line of Sight / Collimation Axis)
SA (vertical axis :Standing Axis)
KA (Trunian Axis)
V (Zenith Angle)
VK (Vertical Circle)
Hz (Horizontal Angle)
HK (Horizontal Circle)

18. HEIGHT OF REMOTE POINT

19. SD (Slope Distance)
HD (Horizontal Distance)
dH (Difference of Height)
hr (Height of Reflector)
hi (Height of Instrument)
E0 (Easting of Station)
N0 (Northing of Station)
H0 (Height of Station)
E (Easting of Target Point)
N (Northing of Target Point)
H (Height of Target Point)

20. Vertical angles
(zenith angle ) .
V%.

21. The vertical angle
Is the angle above or below a horizontal plane through the point of observation
The angle above the horizontal plane is +ve vertical angle (angle of elevation)
The angle below the plane is –ve angle (angle of depression)

22. Measuring vertical angles
Theodolite is set over point P the following vertical angles circle readings were recorded on targets at points A and B. Calculate the vertical angles to points A and B
Point observed
F.L
F.R
Reduced F.L
Reduced F.R
Mean vertical angle A
85 36´
274 28´
4 ´
4  28´
4 26´ B
98º 48´
261 08´
-8 48´
-8 52´
-8 50´