The survey in which the earth's curvature is also considered is called
Geodetic survey
In the field of surveying, different methods are employed depending on the size of the area being surveyed and the required precision. A key factor that dictates the choice of survey method is whether the Earth's curvature needs to be taken into account.
Geodetic Survey Explained
A geodetic survey is a type of surveying in which the curvature of the Earth is specifically considered. This method is used for large areas where the effect of the Earth's spherical shape becomes significant and cannot be ignored. The primary goal of a geodetic survey is to determine the precise positions of widely spaced points on the Earth's surface, as well as their relative heights. Due to the consideration of the Earth's curvature, calculations in geodetic surveying involve spherical trigonometry or advanced geodetic computations.
- Purpose: To establish precise control networks for large-scale mapping, international boundaries, and major engineering projects like long tunnels or bridges.
- Area Size: Typically covers areas larger than 250 square kilometers (or approximately 100 square miles).
- Precision: High precision and accuracy are paramount, accounting for the true shape of the Earth.
Plain Survey vs. Geodetic Survey
To better understand the distinct characteristics of a geodetic survey, it is helpful to compare it with a plain survey (also known as a plane survey).
| Feature | Plain Survey | Geodetic Survey |
|---|---|---|
| Earth's Curvature | Ignored | Considered |
| Area Size | Small areas (typically < 250 km2) | Large areas (typically > 250 km2) |
| Shape of Earth | Assumed flat | Assumed spherical (or ellipsoidal) |
| Line between Points | Straight line | Arc (geodetic line) |
| Calculations | Plane geometry and trigonometry | Spherical trigonometry and advanced geodesy |
| Accuracy | Lower precision over large distances | High precision over long distances |
Understanding Other Survey Types
It's important to differentiate geodetic survey from other types of surveys mentioned in the options:
- Topographical survey: This type of survey focuses on determining the position of natural and artificial features on the ground, as well as elevation differences. It primarily aims to create maps that show the topography (relief) of an area. While it can be either plain or geodetic, the defining characteristic is mapping surface features, not specifically accounting for curvature.
- Preliminary survey: This is a general term often used for the initial phase of a survey project, where reconnaissance and initial data collection are performed to gather basic information about the site and plan the detailed survey work. It's a phase of surveying, not a specific type defined by considering Earth's curvature.
Therefore, the survey in which the Earth's curvature is also considered is definitively known as a geodetic survey.
Important Questions from Fundamental Concepts
Plumb bob lines at two different places in geodetic surveying will _____.
Calculate the length of one division of the vernier scale, if least count of the combination of main and vernier scale is 0.02 mm. The least count of the main scale is 1 mm.
Plumb bob lines at two different places in plane surveying are _____.
Determining different strata in the earth's crust is referred as _________.
- Which of the following is not a typical cross staff variation?
