SURVEYING( Part 4)
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COMPUTATION OF AREA
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COMPUTATION OF AREA
That is very important to compute the area in surveying. There are many method of compute area in surveying. We uses those methods because the land should not regular shapes. To determine the area of irregular shape land different methods are used. The following is a hierarchical representation of the various method of computation of area.
(i) Graphical Method.
(ii) Instrumental Method.
Here, Graphical method is mostly used in surveying to compute the area of land. In this method, a large square or rectangle is formed within the area in the plan.Then ordinates drawn in regular intervals from the side of the square or curved boundary. The middle area is calculated in the usual way. The boundary area is calculated according to the following rules-
Here, Graphical method is mostly used in surveying to compute the area of land. In this method, a large square or rectangle is formed within the area in the plan.Then ordinates drawn in regular intervals from the side of the square or curved boundary. The middle area is calculated in the usual way. The boundary area is calculated according to the following rules-
(i) Trapezoidal Rule
(ii) Simpson's Rule
TRAPEZOIDAL RULE
For applying the trapezoidal rule,boundaries between the ends of ordinates are assumed to be straight. Thus the area enclosed between the base line and irregular boundary lines are considered as trapezoids.
TRAPEZOIDAL RULE
Total Area = . d/2*(O1 + 2O2 + ...... + 2 On-1 + On)
TRAPEZOIDAL RULE
= common distance/2 * ( 1st Ordinate + last Ordinate + 2( sum of other Ordinate)
Limitation- There is no limitation for this rule.This rule can be applied for any number of ordinate.
Limitation- There is no limitation for this rule.This rule can be applied for any number of ordinate.
SIMPSON'S RULE
Here, the boundary between ends of ordinates are assumed to form an arc of a parabola. Hence, Simpson's rule is sometimes called parabolic rule.
SIMPSON'S RULE
Total Area = d/3*( O1 + On + 4( O2 + O4 +.....) + 2( O3 + O5 + .....))
= common distance/3 * ( 1st Ordinate + last Ordinate + 4( sum of enen Ordinates) + 2( sum of odd Ordinates))
Limitation- This rule is applicable only when the number division is even i.e the number of ordinates is odd.
- Difference between Trapezoidal Rule and Simpson's Rule-
TRAPEZOIDAL RULE SIMPSON'S RULE
1. The boundary between the ordinate is 1. The boundary between the ordinates
consider straight. consider an a arc of parabola.
2. There is no limitation. This rule can be 2. This rule is applicable only when
applied for any number the number division is even i.e
of ordinate. the number of ordinates is odd.
3. It gives approximate results. 3. It gives a more accurate result.I am a Civil Engineer and knowledgecivilengineer.blogspot.com is my blog about the basic knowledge of Civil Engineering.Here, you can learn the questions and answers of interview for a civil engineer.
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