surveying
Faculty of Engineering Civil
Engineering Department
(Surveying 1)
Dr. Mohamed Fawzy
Lecture 6
CIPn 111 – Surveying 1
Theodolite
Basic Definition
 The Theodolite is an instrument that is used to determine horizontal and vertical
angles through horizontal and vertical circle readings.
‫الثيودوليت هو جهاز لقياس الزوايا األفقية والرأسية بواسطة قراءات الدائره األفقية والرأسية‬
Lecture 6
CIPn 111 – Surveying 1
Theodolite
Vernier
‫فيرنير‬
Very old and
obsolete
Lecture 6
Types of Theodolite
Optical
‫بصرى‬
Hz are VL circles are made from
glass and the reading are taken by
circle reading eyepiece
Digital
‫رقمى‬
Angular readings are
displayed digitally on
screen
CIPn 111 – Surveying 1
Theodolite
Vernier
‫فيرنير‬
Lecture 6
Basic Definition
Optical
‫بصري‬
Digital
‫رقمى‬
CIPn 111 – Surveying 1
Theodolite
Lecture 6
Theodolite Axis
CIPn 111 – Surveying 1
Theodolite
Adjustment of Theodolite
The adjustment of a theodolite is of two kinds:
1-Temporary Adjustment ‫الضبط المؤقت‬:
At each station point, before taking any observation, it is required to carry out some
operations in sequence. The set of operations those are required to be done on an
instrument in order to make it ready for taking observation is known as temporary
adjustment. Temporary adjustment of a theodolite consists of following operations
:‫يتم الضبط المؤقت عند كل نقطة يتم وضع الجهاز عليها وقبل أخذ أى أرصاد وتنقسم الى‬
Centring ‫التسامت‬,
Leveling ‫ األفقية‬,
Focusing ‫التطبيق‬.
Lecture 6
CIPn 111 – Surveying 1
Theodolite
Temporary Adjustment of Theodolite
Centering ‫التسامت‬
The operation involved in
placing the vertical axis
of the instrument exactly
over the station mark is
known as centering.
‫هو عباره عن أن المحور الرأسى‬
‫للجهاز يمر بالنقطة المحتلة‬
Lecture 6
CIPn 111 – Surveying 1
Theodolite
Temporary Adjustment of Theodolite
Leveling ‫األفقية‬
Leveling of an instrument is done to make the
vertical axis of the instrument truly vertical.
This is done using the three levelling screws and
the plate bubble those are present in a theodolite
instrument.
‫ضبط األفقية للجهاز هو جعل المحور الرأسى للجهاز رأسى‬
‫فعال أى موازى ألتجاه الجاذبية‬
Lecture 6
CIPn 111 – Surveying 1
Theodolite
Temporary Adjustment of Theodolite
Focusing ‫التطبيق‬
Telescope
 To obtain the clear reading, the image
formed by the objective lens should fall
in the plane of diaphragm and the focus
of eye-piece should also be at the plane of
diaphragm. This is being carried out by
removing parallax by proper focusing of
objective and eye-piece.
Lecture 6
CIPn 111 – Surveying 1
Theodolite
Reticule
‫حامل الشعرات‬
Lecture 6
CIPn 111 – Surveying 1
Theodolite
Permanent Adjustment of Theodolite
‫الضبط الدائم‬
The permanent adjustments are made to establish the
relationship between the fundamental lines of the
theodolite so, the permanent adjustments in case of a
theodolites are ‫يتم عمل الضبط الدائم للتأكد من العالقات التالية بين‬
‫ محاور الجهاز‬:
(a)The horizontal axis must be perpendicular to the
vertical axis
‫المحور األفقى عمودى على المحور الرأسى‬
(b) The axis of the telescope level must be parallel to the
line of collimation.
‫محور التليسكوب موازى لمحور العدسات‬
Lecture 6
CIPn 111 – Surveying 1
Theodolite
(c) The line of collimation must be at
right angles to the horizontal axis.
‫محور العدسات عمودى على المحور األفقى‬
(d) The axis of the plate levels must be
perpendicular to the vertical axis.
‫محور ميزان التسوية الطولى عمودى على المحور‬
‫الرأسى‬
Lecture 6
CIPn 111 – Surveying 1
Theodolite
Face Left/Right
We can also eliminate some errors using especial ways for observations as using Face Left
and Face Right: eliminate any tilt for the vertical axis of the device on the horizontal axis,
if any.
Face Left (FL): VL circle
left of observer
Face Right (FR): VL
circle right of observer
Lecture 6
CIPn 111 – Surveying 1
Theodolite
Concept of measuring Horizontal
Angle
A
C
HCRA
θ
0
B
HCRC
Horizontal Circle
Spatial Directions are projected on the
horizontal circle of the theodolite, and
so Horizontal Circle Readings (HCR)
are obtained
<ABC
Hz circle fixed and pointer
moves with alidade
Horizontal angle <ABC = θ = HCRC – HCRA
Hz angle: It is the angle between the projection ‫ مسقط‬of two lines on the
horizontal plane passing by the theodolite clockwise direction ‫مع عقارب الساعة‬
Lecture 6
CIPn 111 – Surveying 1
Theodolite
Concept of measuring Vertical
Angle
V angle: It is the angle measured in the vertical plane ‫ فى المستوي الرأسى‬between the
line joining the theodolite-target (line of sight ‫ ) خط النظر‬and the horizontal
plane,
Lecture 6
CIPn 111 – Surveying 1
Theodolite
Lecture 6
Concept of measuring Vertical
Angle
CIPn 111 – Surveying 1
Any questions ?