Geomatics Instruments

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Questions and Answers

What is the definition of a level surface in surveying?

A vertical line that is perpendicular to the local level surface

A curved surface that follows the local direction of gravity

A line that follows the local direction of gravity as indicated by a plumb line

A horizontal plane perpendicular to the local vertical line (correct)

What type of distance is measured between two targets at different elevations?

Vertical distance

Diagonal distance

Slope distance (correct)

Horizontal distance

What is the term for the horizontal length between vertical lines at two points in plane surveying?

Horizontal distance (correct)

Distance definition

Vertical distance

Slope distance

What is the purpose of taping equipment in direct observation methods?

To measure distances accurately Signup and view all the answers

What is the term for a line that follows the local direction of gravity as indicated by a plumb line?

Plumb line Signup and view all the answers

What type of distance is measured in the horizontal plane between two targets even if they are at different elevations?

Horizontal distance Signup and view all the answers

What is the term for a curved surface that at every point is perpendicular to the local vertical line?

Level surface Signup and view all the answers

What is the purpose of geomatics instruments in surveying?

To observe distances directly Signup and view all the answers

What is the primary purpose of a plumb bob or line in taping equipment?

To give stability in the vertical direction Signup and view all the answers

What is the typical length of a fiber tape?

30 - 50 - 100 m Signup and view all the answers

Which of the following instruments is used for indirect observation?

EDM Signup and view all the answers

What is the primary material used to make Invar tape?

Nickel-steel alloy Signup and view all the answers

What is the purpose of a range pole in taping equipment?

To maintain the tape's alignment Signup and view all the answers

What is the typical accuracy of an Invar tape?

Very high accuracy Signup and view all the answers

What is the function of taping pins in taping equipment?

To mark tape lengths Signup and view all the answers

What is the purpose of a circular level bubble in taping equipment?

To ensure the pole is vertical Signup and view all the answers

What is the primary purpose of using a pole tripod in geomatics?

To maintain the verticality of the pole Signup and view all the answers

What is the correct procedure for lining in during taping observation?

Marking the line to be measured at both ends Signup and view all the answers

What is the purpose of plumbing in taping observation?

To ensure the poles are vertical Signup and view all the answers

What should be ensured before starting work during taping observation?

The type of tape being used is identified Signup and view all the answers

How is the taping measurement applied on level ground with small slopes?

Directly on the ground Signup and view all the answers

What is the consideration for considering the ground as horizontal?

Slope between two points equal to 2% Signup and view all the answers

Why is the relative error of distance negligible on level ground with small slopes?

Because the slope is very small Signup and view all the answers

What is the primary advantage of direct measuring methods?

Applicable on level grounds with small slopes Signup and view all the answers

Study Notes

Instruments of Direct Observation

Fiber tape is made of high-grade linen with fine copper wires to provide additional strength and prevent excessive elongation.
Invar tape is made of a special nickel-steel alloy to reduce length variations caused by differences in temperature.
Odometer converts the number of revolutions of a wheel of known circumference to a terrain distance.

Taping Equipment for Observation

Range pole is a lining metallic rod used to mark the line being measured, 1.5 to 2 m in length.
Taping pins are sharply pointed at one end and have a round loop at the other end, used to mark tape lengths.
Plumb bob or line is a weight with a fine point attached to a cord, used to give vertical direction.
Circular Level Bubble is a tube of glass filled with a sensitive non-freezing liquid with a small air bubble, used to ensure the pole is vertical.

Distance Definition

In plane surveying, distance between two points is the horizontal distance between vertical lines at these two points.
Types of distance include horizontal distance, slope distance, and vertical distance.

Principle of Taping Observation

Observation of horizontal distances by taping involves applying the known length of a tape directly to a line "less than the tape length".
The tape is held above ground in a horizontal position as possible by the eye observer.

Steps of Taping Observation

LINING IN: marking the line to be measured at both ends using poles.
PLUMBING: ensuring the poles are vertical using the plumb bob.
APPLYING TENSION: holding the tape straight and at the same elevation.
READING THE TAPE RECORDING THE DISTANCE: identifying the type of tape being used to avoid mistakes.

Taping Observation Methods

The method of direct measuring depends on the ground topography.
Level ground: taping measurement is applied on the ground.
Sloping ground: taping measurement is applied above the ground.

Level and Sloping Ground

If the slope between two points is equal to 2%, the ground is considered horizontal, and the taping measurement is applied directly on the ground without mistake.