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Chapter: Civil Surveying - Advanced Topics in Surveying

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Important Questions and Answers: Advanced Topics in Surveying

Civil Surveying - Advanced Topics in Surveying


Advanced Topics in Surveying

 

1.                 Hydrographic Survey:

 

Hydrographic Survey is that branch of surveying which deals with the measurement of bodies of water. It is the art of delineating the submarine levels, contours and features of seas, gulfs, rivers and lakes.

 

2.                 Sounding :

 

The measurement of depth below the water surface is called sounding.

 

3.                 Tides:

 

All celestial bodies exert a gravitational force on each other. These forces of attraction between earth & other celestial bodies cause periodical variations in the level of water surface, known as tides.

 

4.                 Equilibrium Theory :

 

The earth is covered all around by the ocean of uniform depth. The ocean is capable of assuming the equilibrium.

 

5.                 Mean sea level :

 

Mean sea level may be defined as the mean level of the sea, obtained by taking the mean of all the height of the tide as measured at hourly intervals over some states period covering a whole number of complete tides.

 

6.                 Fathometer :

 

A fathometer is used for ocean sounding where the depth of water is too much and to make a continuous and accurate record of depth of water below the boat or ship at which it is installed.

 

7.                 Photographic Survey :

 

It is also called photogrametry. It is a method of surveying in which plant or maps are prepared from photographs taken from Suitable camera station. It is divided into two.

 

Terrestrial photography

Aerial photography

 

8.                 Photo theodolite:

 

It is the combination of photo with theodolite and is used for taking photographs & measuring the angles which the vertical plane of collimation makes with the base line.

 

 

 

 

9.                 Stereoscopic pairs:

It means two photos are obtained for a Single object from two point one at each.

 

 

10.            Parallax:

 

In normal binocular vision the apparent movement of a point viewed first with one eye and then the other is known a parallax.

 

11.            Angle of Parallax:

 

It is the angle of convergence of the two rays of vision.

 

12.            Stereoscopic fusion:

 

If a pair of photographs is taken of an object from two slightly different positions of the camera and then viewed by an apparatus which ensures that the left eye sees only the left-hand picture & right eye is directed to the right hand picture, the two separate images of the object will fuse together is the brain to provide the observer with spatial impression. This is known as a Stereoscopic fusion.

 

13.            Stereo pair:

 

The pair of two such photographs is known as stereo pair. The effect of distortions exist in a single photograph may be eliminated through a large extend of stereo pairs.

 

14.            Parallax bar:

 

A parallax bar used to measure difference of two points, consists of a bar which holds a fixed plate of transparent material near the left end and a movable plate to the right end.

 

15.            Floating mark:

 

In parallax bar, when the two dots are viewed properly under a stereoscope they fuse into a single dot called floating mark.

 

16.            Mosaics :

 

Such an assembly of getting series of overlapping photograph is called mosaic.

 

17.            Types of EDM instrument :

 

Tellurimeter

Geodimeter

Distomats

 

18.            Cartography :

 

It is the marking and study of maps in all their aspects. It is an important branch of graphics, since it is an extremely efficient way of manipulating, analyzing, & expressing ideas, forms & relationships that occur in two & three dimensional space.

 

19.            Cadastral survey :

Cadastral means, 'Registration concern Land Survey'. It is of one of based on national land survey based on land survey law.

 

20.            Modulation :

 

Amplitude modulation Frequency modulation

 

In amplitude modulation, the carrier wave has constant frequency & the modulating wave (the measurement wave) in formation is conveyed by the amplitude of the carrier wave. In the frequency modulation the carrier wave has constant amplitude, while the frequency varies in proportion to the amplitude of the modulation wave.

 

21.            Methods of Measuring Velocity flow:

 

Surface float

Sub surface float

Velocity ropes

Picot tube method &Current meter mean.



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