Surveying
LBYCIVB
EXERCISE No. 1
STADIA INTERVAL FACTOR
Student Name:____________________ Date Performed: _____________
Group No.: ___________ Date Submitted: _____________
Group Leader: _______________________ Grade: ___________
1. Objective: The objective of this exercise is to determine the stadia interval factor of an engineer’s transit or theodolite.
2. Background:
The telescope of an engineer’s transit, theodolite, plane table alidade, and many levels are furnished with stadia hairs in addition to the regular cross hairs. One stadia hair, the upper cross hair, is above and the other, the lower cross hair, an equal distance below the middle cross hair.
The process of taking stadia measurements consists of observing, through the telescope, the apparent locations of the two stadia hairs on the rod, which is held in a vertical position. The interval thus determined, called the stadia intercept/interval/reading, is a direct function of the distance from the instrument to the face of the stadia rod.
The principle of the stadia method is based in Figure 2.3 shown, wherein the line of sight of the telescope is horizontal and the rod is vertical. For the notation
i = spacing between stadia hairs, c = distance from the instrument center to the objective lens center, f = focal length (objective lens to focal point), d = distance from the focal point F to the face of the rod, C = (f + c) = stadia constant, • for internal focusing telescope, C = 0.0 and • for external focusing telescope, C = 0.3 m D = (C + d) = distance from the instrument center to the face of the rod, and S = stadia intercept or interval
Considering Fig. 2.3, by similar triangles,
f / i = d / S
The horizontal distance d, from focal point to the rod is
d = ( f / i )*S but K = f / i
therefore,
EXERCISE No. 1
STADIA INTERVAL FACTOR
Student Name:____________________ Date Performed: _____________
Group No.: ___________ Date Submitted: _____________
Group Leader: _______________________ Grade: ___________
1. Objective: The objective of this exercise is to determine the stadia interval factor of an engineer’s transit or theodolite.
2. Background:
The telescope of an engineer’s transit, theodolite, plane table alidade, and many levels are furnished with stadia hairs in addition to the regular cross hairs. One stadia hair, the upper cross hair, is above and the other, the lower cross hair, an equal distance below the middle cross hair.
The process of taking stadia measurements consists of observing, through the telescope, the apparent locations of the two stadia hairs on the rod, which is held in a vertical position. The interval thus determined, called the stadia intercept/interval/reading, is a direct function of the distance from the instrument to the face of the stadia rod.
The principle of the stadia method is based in Figure 2.3 shown, wherein the line of sight of the telescope is horizontal and the rod is vertical. For the notation
i = spacing between stadia hairs, c = distance from the instrument center to the objective lens center, f = focal length (objective lens to focal point), d = distance from the focal point F to the face of the rod, C = (f + c) = stadia constant, • for internal focusing telescope, C = 0.0 and • for external focusing telescope, C = 0.3 m D = (C + d) = distance from the instrument center to the face of the rod, and S = stadia intercept or interval
Considering Fig. 2.3, by similar triangles,
f / i = d / S
The horizontal distance d, from focal point to the rod is
d = ( f / i )*S but K = f / i
therefore,