EXPERIMENT NO: 1 DATE: TACHEOMETRIC CONSTANTS...long chord T1T2 (L) given by the formula, Mark T1 on...

Don Bosco College of Engineering, Fatorda-Goa Page 1

Lab Manual (Surveying II)

EXPERIMENT NO: 1 DATE:

TACHEOMETRIC CONSTANTS

Aim: Determination of the Multiplying and additive constant of given Tacheometer

Equipment: A tacheometer with tripod, tape, leveling staff, wooden pegs, ranging rods etc.

Course Outcome: CE6.6.1 Apply the measurement concepts, techniques and equipment used in

land surveying with correction required for geodesy

Figure:

Formulae: When the line of sight is horizontal, then D = KS +C

Where,

D = Horizontal distance between instrument station and staff station. K = Multiplying constant of a

tacheometer

S = Staff intersect i.e. difference between top and bottom stadia hair reading.



When line of sight is inclined and staff vertical then:

D = KS cos2 θ + C cosθ

Where,

D = Horizontal distance between instrument station and staff station. K = Multiplying constant of a tacheometer


θ = The inclination of the line of collimation to the horizontal.

C = The additive constant of the tacheometer Procedure:

1) Select an instrument station A on a fairly leveled ground and fix a peg.

2) Do the temporary adjustment over A.

3) With vertical circle to the left of the observer and reading 00°00

’00

” bisect staff held at 10m, 20m,

and 30m from A along straight line.

4) Note down the staff reading against top and bottom stadia hair on staff held at 10m, 20, 30m from

A.

Observation Table:

Instrument Staff Distance Vertical Stadia hair Reading Remark

station station

angle Top Center Bottom

D1

A D2

D3

D4



Calculation:

D = Ks + C

For three staff stations,

D1 = Ks1+C ------- (1)

D2 = Ks2+C ------- (2)

D3 = Ks3+C------- (3)

D4 = Ks4+C------- (3)

As , S1, S2, S3 can be known solving (1) &(2), (2) & (3) , (1) & (3) to get 3 values

of m & c ,then average of three values is required answer.

Result: a) For horizontal line of collimation;

1) The additive constant ‘C’ for a given tacheometer is found out to be

2) The multiplying constant ‘K’ for a given tacheometer is found to be ---------



QUESTIONNARE

1. What are the fundamental parts of a theodolite?

2. What are the fundamental lines in a theodolite?

3. What is the difference between a level and a theodolite?

4. Name different types of theodolite?

5. Why it is called a transit theodolite?

6. How do you measure height of instrument?

7. What are the functions of spirit levels provided in instrument?

8. How many axes are present in this instrument?

9. What do you understand by the following terms?

a. Telescope normal and inverted

b. Face left and face right observations

c. Swing left and swing right

10. Which of the following is carried out first : Leveling and centering

11. What is the least count of the device provided?




DETERMINATION OF GRADIENT BY TACHEOMETRIC SURVEY

AIM: Determination of gradient of given length of road by Tacheometric survey

(horizontal & vertical difference between two points)

Equipment: A tacheometer with tripod, tape, levelling staff, wooden pegs, ranging rods etc.

Course Outcomes: CE6.6.1 Apply the measurement concepts, techniques and equipment used in

land surveying with correction required for geodesy

Formulae: When the line of sight is horizontal, then D = Ks + C Where,

D = Horizontal distance between instrument station and staff station. K = f/i=100 Multiplying

constant of a tacheometer

C= (f+d)=0 additive constant of a tacheometer

S = Staff intersect i.e. difference between top and bottom stadia hair reading. When line of sight is

inclined and staff vertical then:

D = KS cos2 θ + C cosθ Where,

D = Horizontal distance between instrument station and staff station. K = Multiplying constant of a

tacheometer


θ = The inclination of the line of collimation to the horizontal.

C = The additive constant of the tacheometer

Distance between P&Q (D)= D12 + D2

2 ±2D1D2Cosα

(+ when α >90; - when α <90)

Gradient = (RLs of P-RLs of Q)/Length

Theory:

Trigomentrical levelling is the branch of surveying in which the relative elevations of the points are



determined from the observed vertical angles and known horizontal distance. Whereas in ordinary

leveling the difference in elevation is ascertained by running a line between the given points.

Let A be the instrument station while P & Q be the staff stations

Procedure:

1. Setup the instrument station A and level it carefully with respect to plate bubble tube. Initialise the

instrument and transfer the instrument point on ground.

2. Select the staff station P and held it properly.

3. Release the vertical circle clamping screw and bisect the staff by making the horizontal line of sight.

4. At the same time the horizontal vernier should read to (00 0’00”) and clamp it in position.

5. Take three staff readings on the staff station and find the stadia intercept.

6. Release the upper plate clamping screw and bisect the another staff at Q again and take all three

staff readings and then determine the staff intercept

7. Determine the horizontal angle between these two staff station and note the value ø.

8. Now determine the horizontal distance and vertical distance between staff station and instrument

station respectively.

9. Determine the horizontal distance between two staff station by applying cosine rule.

10. Determine the difference in elevation of the two staff station.

11. Finally determine the gradient

Observation Table:

Instrument Staff Horizontal Vertical Stadia hair Reading

station station angle angle Top Axial Bottom

A P

Q

Result: The gradient of given length of two staff station is found to be ___________ by

tacheometric survey.



QUESTIONNAIRE:

1. If the vernier of the vertical circle reads 36 degree, what will be the reading on the opposite

vernier of the vertical circle?

2. How would you measure the magnetic bearing of a line with a theodolite?

3. What is meant by fixed hair and movable hair method of stadia surveying?

4. What are tacheometric constants?

5. What is the maximum and minimum distance you can view with the instrument?


SETTING OUT OF SIMPLE CIRCULAR CURVE BY LINEAR METHOD

Aim: To set out a simple curve by linear method having radius R m and an external

deflection angle of ϕ°.

Instruments: Pegs, arrows, plumb bob, cross staff, ranging rod .

Course Outcome: CE6.6.5: Learn, apply, carry out filed exercises on setting out works

Theory: Linear methods are used when:

High degree of accuracy is not required

The curve is short

Linear methods for setting out curve include

1. By perpendicular offsets from long chord.

2. By perpendicular offsets from tangents (T)

3. Radial offsets from the tangent (T)

Procedure:

I By perpendicular offsets

from long chord.

1. Stretch the chain along the

long chord T1T2 (L) given by

the formula, Mark T1 on it

which is point of curve Mark

D along the chain line which is

midpoint of T1T2.

2. From D erect a perpendicular

offset equal to the mid –

ordinate O0.

3. Mark E which is the mid point

of the curve. Perpendicular offsets from long chord

4. Divide T1D into intervals. Mark these point as various ordinates

5. Erect perpendicular offsets from these points given by the relation

Ox = √( R2 -x

2) - (R - O0)



6. Repeat the above steps to get

the other half of the curve.

II By perpendicular offsets from

tangents (T)


tangent T1V given by the relation

2. Divide the tangents into equal

number of possible parts (say 4m

interval ) and name them as O4,

O6 , O12, O16 and OT1V.

3. Set perpendicular offsets from

these points given by the equation

Ox= R – {√ ( R2 -x

2 )

to get points on the curve

4. Repeat the steps 1 to 3 to get the

other half of the curve

III Radial offsets from the

tangent (T)


tangent T1B given by the relation

2. From T1 set out perpendicular

and mark the centre ot the curve

O by measuring radius of R m

and fix a ranging rod at O.

3. From O4 sight O and set out

offset given by the equation

Ox = { √ (R2 + x2 ) } - R.}

4. Repeat the steps for all the

other points namely O4, O6,

O12, O16.

5. Repeat the procedure for the

next tangent.

Results: A simple curve of radius was set out by linear method.

V



QUESTIONNAIRE:

1 Explain Rankines method of setting out simple curve.

2 Where are curves used in construction projects?

3 What do understand by reverse curves? Why should reverse curves be avoided?

4 Why do we need transition curves?




SETTING OUT OF SIMPLE CIRCULAR CURVE BY RANKINES METHOD

Aim: To set out a compound curve

Instruments: Theodolite, tapes (15m and 25 m), ranging rods

Course outcome: CE6.6.5: Learn, apply, carry out filed exercises on setting out works

Theory: Laying out a curve by Deflection angle (Rankine's Method)

In this method, curves are staked out by use of deflection angles turned at the point of

curvature from the tangent to points along the curve. The curve is set out by driving pegs at

regular interval equal to the length of the normal chord. Usually, the sub-chords are provided

at the beginning and end of the curve to adjust the actual length of the curve. The method is

based on the

assumption that there

is no difference

between length of the

arcs and their

corresponding chords

of normal length or

less. The underlying

principle of this

method is that the

deflection angle to any

point on the circular

curve is measured by

the one-half the angle

subtended at the centre

of the circle by the arc

from the P.C. to that point.

Now, for the first tangential angle Δ1, from the property of a circle

Arc T1 a = R x 2 δ1radians

Assuming the length of the arc is same as that of its chord, if C1 is the length of the first chord

i.e., chord T1 a, then



(Note: the units of measurement of chord and that of the radius of the curve should be same).

Similarly, tangential angles for chords of nominal length, say C,

And for last chord of length, say Cn

The deflection angles for the different points a, b, c, etc. can be obtained from the tangential

angles. For the first point a, the deflection angle Δa is equal to the tangential angle of the

chord to this point i.e., δ 1. Thus,

Δa = δ1.

The deflection angle to the next point i.e., b is Δb for which the chord length is T1 b. Thus, the

deflection angle



Thus, the deflection angle for any point on the curve is the deflection angle upto previous

point plus the tangential angle at the previous point.

Procedure:

The simple curve is set up by the method of deflection angles. The procedure is as follows

1. After having known any four parts, calculate the rest of the three.

2. Knowing Tangent Lengths, Locate points T1 and T2 by linear measurements from the point of

intersection.

3. Calculate the length of the curves. Calculate the chainage of T1 and T2 as usual.

4. Calculate Tangential angles for the first e by Rankines method

5. Set the theodolite at T1 and set out the first branch of the curve as already discussed.

6. After having located the last point D check if the angle subtended at the centre is equalt to

deflection angle ϕ

Result: The Simple curve was set up using Rankine’s Method



QUESTIONNAIRE

1. What is point of tangency and curvature?

2. What are compound curves?

3. What are right hand curves, left hand curves?

4. What rea the difficulties in setting out curves?

5. How do you check the accuracy of the work?

6. What are obstacles possibly faced during setting out?




TOTAL STATION Aim: To determine horizontal, sloping and vertical distances between two points using total

station

Equipment: Total station, Tripod, Prism

Course Outcome: CE6.6.3. Learn to use modern survey equipment to measure angles and

distances

Theory: Total station is electronic modern surveying instrument used in construction. It is

integrated with electronic distance measurement (EDM) to read slopes and difference in

elevations

Coordinate measurement

Coordinates of an unknown point relative to a known coordinate can be determined using the

total station as long as a direct line of sight can be established between the two points. Angles

and distances are measured from the total station to points under survey, and

the coordinates (X, Y, and Z or easting, northing and elevation) of surveyed points relative to

the total station position are calculated using trigonometry and triangulation. To determine an

absolute location a Total Station requires line of sight observations and must be set up over a

known point or with line of sight to 2 or more points with known location.

For this reason, some total stations also have a Global Navigation Satellite System receiver

and do not require a direct line of sight to determine coordinates. However, GNSS

measurements may require longer occupation periods and offer relatively poor accuracy in the

vertical axis.

Angle measurement

Most modern total station instruments measure angles by means of electro-optical scanning of

extremely precise digital bar-codes etched on rotating glass cylinders or discs within the

instrument. The best quality total stations are capable of measuring angles to 0.5 arc-second.

Inexpensive "construction grade" total stations can generally measure angles to 5 or 10 arc-

seconds.

Distance measurement



Measurement of distance is accomplished with a modulated microwave or infrared carrier

signal, generated by a small solid-state emitter within the instrument's optical path, and

reflected by a prism reflector or the object under survey. The modulation pattern in the

returning signal is read and interpreted by the computer in the total station. The distance is

determined by emitting and receiving multiple frequencies, and determining the integer

number of wavelengths to the target for each frequency. Most total stations use purpose-built

glass corner cube prism reflectors for the EDM signal. A typical total station can measure

distances with an accuracy of about 1.5 millimetres (0.0049 ft) + 2 parts per million over a

distance of up to 1,500 metres (4,900 ft).

Reflector less total stations can measure distances to any object that is reasonably light in

color, up to a few hundred meters.

Procedure:

1. Open the terrasync software and select the tab ‘GENERAL SURVEY’ (Fig 1).

Fig 1 Fig 2

2. Then Select ‘INSTRUMENT SET-UP’(Fig 2).

3. Level the instrument by getting the electronic

bubble at the centre with

the help of screws. Leveling the Total Station

Fig 3

must be accomplished to sufficient accuracy otherwise the instrument will not report results.



Leveling the instrument takes 30 to 45 minutes (Fig 3).

4. Make sure you can see all targets from the instrument station before going through the

procedure. Tripod legs should be equally spaced . Tripod head should be approximately

level. Head should be directly over survey point. Place Instrument on Tripod

Secure with centering screw while bracing the instrument with the other hand.

Insert battery in instrument before leveling .Focus the optical plummet on the survey point

Adjust the leveling foot screws to center the survey point in the optical plummet reticle .

Move your head from side-to-side to test for image shift (i.e. parallax). Repeat the reticle

focus step if parallax is significant

NOTE: When the instrument operator changes the reticle focus may need to be adjusted)

5. After the instrument has been levelled select ‘NEW JOB’ (fig4, Fig 5) Adjust the reticle

(i.e. cross-hair) focus adjustment until reticle image is sharply focused. telescope to target

and adjust the focus ring until target is focused

Fig 4 Fig 5

6. Feed the required details such as Job name, instrument point name, Code back sight

height, azimuth in INSTRUMENT SET UP (Fig 6).



Fig 6 Fig 7

Next, sight the staff point and click on tab ‘MEASURE’.(Fig 8) The results will be

displayed on screen.

7. Store the data and repeat the recording procedure for other points (fig 9)

Fig 9 Fig 10

8. Select ‘COGO’ (Fig 10) tab and select

‘INVERSE’ command to get the distance &

difference in elevation of different points.

9. Note down the readings displayed on screen

which indicate the difference in elevation

and distances. Fig 11

Fig 11

Result: The distance between two points

A: Horizontal distance is ______m

B: Vertical difference is _________m

C: Slope distance is __________m



QUESTIONNAIRE:

1. What is the least count of instrument used?

2. What is the accuracy of the instrument used?

3. Explain the basic features of total station.

4. Explain the basic levelling and focusing procedures in total station.



EXPERIMENT NO:6 DATE:

SETTING OUT BUILDING PLAN Aim: setting out a building plan using theodolite and level

Instruments: 1-digital theodolite

2- 30m tape

Course Outcome: CE 6.6.5 Learn, apply, carry out filed exercises on setting out works

Procedure:

1- Set up the thodolite on point 1

2- Make the horizontal angle =00 00 00 towards

3-Use the following table to set out all points by

a- Rotating the theodolite with the appropriate angel

b- Measure the distance from point 1 in the direction

of the theodolite towards the required point

point X m Y m angle Distance (m)

° ‘ “

1 0 0 0 0

2 0 8 00 00 00 8.00

3 4 8 26 33 54 8.94

4 6 6 45 00 00 8.49

5 6 4 56 18 36 7.21

6 4 4 45 00 00 5.66 7 4 2 63 26 06 4.47

8 8 2 75 57 50 8.25 9 8 0 90 00 00 8.00



Result: Outline of the building plan was plotted on ground

8m



QUESTIONNARE:

1 Explain the potential sources of errors while setting out building plan

2 Explain the procedure adapted in setting out.

3 What are the checks given to confirm the accuracy?

4 What rea the instruments required to set out?




AREA DETERMINATION USING HAND HELP GPS

Aim: To Use GPS in locating and obtaining time information in all weather conditions, anywhere on

or near the Earth where there is an unobstructed line of sight to GPS satellites

Course Outcome:

CE6.6.2. To understand the principles and operation of the global positioning system

and Remote sensing.

CE6.6.3. Learn to use modern survey equipment to measure angles and distances

Instruments: Hand held GPS Trimble Juno SA

Theory: GPS satellites circle the earth twice a day in a very precise orbit and transmit signal

information to earth. GPS receivers take this information and use triangulation to calculate

the user's exact location. Essentially, the GPS receiver compares the time a signal was

transmitted by a satellite with the time it was received. The time difference tells the GPS

receiver how far away the satellite is. Now, with distance measurements from a few more

satellites, the receiver can determine the user's position and display it on the unit's electronic

map. The 24 satellites that make up the GPS space segment are orbiting the earth about

12,000 miles above us(by US dept of defense). They are constantly moving, making two

complete orbits in less than 24 hours. These satellites are traveling at speeds of roughly 7,000

miles an hour

Accuracies now routinely achieved in measurement of baseline lengths in relative mode,

using high precision Geodetic instrumentation, with many hours of observations and scientific

data processing, are as follows:

(i) 0.1 - 4 mm in Local surveys (10 m-100 km baseline lengths)

(ii) 4-10 mm in Regional surveys (100-1000 km baseline lengths)

(iii) 1-2 cm in Global surveys (1000-10000 km baseline lengths)



Procedure: To determine area

1. Open the ‘Terra Sync” Software (Fig 1)

Fig 1 Fig 2 Fig 3 Fig 4

2. Click on ‘DATA’ and create a ‘NEW FILE’ (Fig 2).

3. Set the GPS device’ height from the ground level (Fig 3).

4. Select the tab ‘COLLECT FEATURES’ and then select ‘AREA

GENERIC’ (Fig 4), which means we ae collecting data to

calculate area.

When the corresponding screen is shown start walking around

the perimeter of the area. Close the loop. In case we do not

return back to the first point the area command enables device

to close the loop by connecting the first and the last point Fig 5

with a straight line. Click ‘OK’

5. Click update features and area will be displayed (Fig 5)

Result: The given area was located and measure to be _____Sq.m



QUESTIONNARE:

1. How is GPS used in civil engineering

2. What are the minimum number of satellite signals required in ordered to give

desirable results?

3. Explain portable GPS

4. How does GPS work?




SATELLITE IMAGES AND ITS INTERPRETATION IN REMOTE SENSING

Aim: To study satellite images and its interpretation in remote sensing

Course Outcome:CE6.6.2. To understand the principles and operation of the global

positioning system and Remote sensing.

Theory:

Interpretation

Interpretation is the processes of detection, identification, description and assessment of

significant of an object and pattern imaged. The method of interpretation may be either visual

or digital or combination of both. Both the interpretation techniques have merits and demerits

and even after the digital analysis the output are also visually analysed.

Combination of 3 bands generates colour composite images.

Source: www.sci-ctr.edu.sg/ssc/publication/remotesense/opt_int.html

The ability of human to identify an object through the data content in an image/photo by

combining several elements of interpretation. There are two types of extraction of

information from the images/photographs namely;

1. Interpretation of data by visual analysis,

2. Semi-automatic processing by computer followed by visual analysis like

generation of vector layer from raster image through onscreen digitisation and

DTM/DEM generation.

http://www.sci-ctr.edu.sg/ssc/publication/remotesense/opt_int.html



Basic elements of interpretation

The interpretation of satellite imagery and aerial photographs involves the study of various

basic characters of an object with reference to spectral bands which is useful in visual

analysis. The basic elements are shape, size, pattern, tone, texture, shadows, location,

association and resolution.

1. Shape: The external form, outline or configuration of the object. This includes natural

features (Example: Yamuna River), in Delhi Man Made feature (Example : Nehru

Stadium, Delhi.

2. Size : This property depends on the scale and resolution of the image/photo. Smaller

feature will be easily indented in large scale image/photo.

3. Pattern: Spatial arrangement of an object into distinctive recurring forms: This can be

easily explained through the pattern of a road and railway line. Eventhough both looks

linear, major roads associated with steep curves and many intersection with minor road.

4. Shadow: Indicates the outline of an object and its length which is useful is measuring the

height of an object. The shadow effect in Radar images is due to look angle and slope of

the terrain. Taller features cast larger shadows than shorter features.

5. Tone: Refers to the colour or relative brightness of an object. The tonal variation is due to

the reflection, emittance, transmission or absorption character of an objects. This may vary

from one object to another and also changes with reference to different bands. In General

smooth surface tends to have high reflectance, rougher surface less reflectance. This

phenomenon can be easily explained through Infrared and Radar imagery .

6. Infrared imagery: Healthy vegetation reflects Infrared radiation much more stronger than

green energy and appears very bright in the image. A simple example is the appearance of

light tone by vegetation species and dark tone by water. Particularly in thermal infrared

images the brightness tone represents warmest temperature and darkness represent coolest

temperature. The image (Fig2) illustrates daytime and night time thermal data. The

changes in kinetic water temperature cause for the tonal changes. Hence time is also to be

taken consideration before interpretation

7. Radar Imagery : Smooth surfaces reflect highly and area blocked from radar signal and

appear dark. Bridges and cities show very bright tone, on the contrary calm water,

pavement and dry lake beds appears very dark tone.

8. Texture: The frequency of tonal change. It creaks a visual impression of surface

roughness or smoothness of objects. This property depends upon the size, shape, pattern

and shadow

9. Location Site : The relationship of feature to the surrounding features provides clues to

words its identity. Example: certain tree species words associated with high altitude areas



10. Resolution: It depends upon the photographic/imaging device namely cameras or sensors.

This includes of spectral and spatial resolutions. The spectral resolution helps in

identifying the feature in specific spectral bands. The high spatial resolutions

imagery/photographs is useful in identifying small objects.

11. Association: Occurrence of features in relation to others.

Hence, careful examination has to be done to identify the features in the imagery

combined with field information.

Interpretation of Common False-Color Images

Though there are many possible combinations of wavelength bands, typically one of four

combinations based on the event or feature to be illustrated. For example, floods are best

viewed in SWIR, NIR and green light because muddy water blends with brown land in a

natural-color image. SWIR light highlights the differences among clouds, ice and snow—all

of which are white in visible light.

The site’s four most common false-color band combinations are:

1. NIR (red), green (blue) and red (green), which is a traditional band combination used to see

changes in plant health.

2. SWIR (red), NIR (green) and green (blue), which is a combination often used to show

floods or newly burned land.

3. Blue (red) and two different SWIR bands (green and blue), which is a combination used to

differentiate among snow, ice and clouds.

4. Thermal infrared, which usually is shown in gray tones to illustrate temperature.

Spectral bands

The wavelengths are approximate; exact values depend on the particular satellite's

instruments:

Blue, 450–515..520 nm, is used for atmosphere and deep water imaging, and can reach

depths up to 150 feet (50 m) in clear water.

Green, 515..520–590..600 nm, is used for imaging vegetation and deep water structures,

up to 90 feet (30 m) in clear water.

Red, 600..630–680..690 nm, is used for imaging man-made objects, in water up to 30 feet

(9 m) deep, soil, and vegetation.

Near infrared (NIR), 750–900 nm, is used primarily for imaging vegetation.

Mid-infrared (MIR), 1550–1750 nm, is used for imaging vegetation, soil moisture

content, and some forest fires.

Far-infrared (FIR), 2080–2350 nm, is used for imaging soil, moisture, geological

features, silicates, clays, and fires.

Thermal infrared, 10400-12500 nm, uses emitted instead of reflected radiation to image

geological structures, thermal differences in water currents, fires, and for night studies.



Radar and related technologies are useful for mapping terrain and for detecting various

objects.

Spectral band usage

For different purposes, different combinations of spectral bands can be used. They are usually

represented with red, green, and blue channels. Mapping of bands to colors depends on the

purpose of the image and the personal preferences of the analysts. Thermal infrared is often

omitted from consideration due to poor spatial resolution, except for special purposes.

True-color uses only red, green, and blue channels, mapped to their respective colors. As

a plain color photograph, it is good for analyzing man-made objects, and is easy to

understand for beginner analysts.

Green-red-infrared, where the blue channel is replaced with near infrared, is used for

vegetation, which is highly reflective in near IR; it then shows as blue. This combination

is often used to detect vegetation and camouflage.

Blue-NIR-MIR, where the blue channel uses visible blue, green uses NIR (so vegetation

stays green), and MIR is shown as red. Such images allow the water depth, vegetation

coverage, soil moisture content, and the presence of fires to be seen, all in a single image.

Many other combinations are in use. NIR is often shown as red, causing vegetation-covered

areas to appear red.

Procedure:

1. Satellite images were downloaded from BHUVAN- Indian Geo platform of ISRO

2. After creating a login for the said website, images were downloaded from the archive

data.

3. Depending on the satellite selected, downloaded images would be saved in 3-5 bands.

Select LISS III which will operate in 4 bands

LISS-3 (RESOURCESAT) Bands

Band Wavelength (µm) Resolution (m)

Band B2 (VIS) 0.52 to 0.59 23.5

Band B3 (VIS) 0.62 to 0.68 23.5

Band B4 (NIR) 0.77 to 0.86 23.5

Band B5 (SWIR) 1.55 to 1.75 23.5

4. Open source software Image J was used to create the composite image

a) Store the satellite images in a folder

b) Open the images (one at a time)

c) Select IMAGE tab COLOR MERGE CHANNELS



d) Assign C1(red) -Band 4 (representing near Infra-red)

C2 (green) -Band 3(representing Red)

C3 (blue) - Band 2 (Representing Green)

C4 (gray) - Band 5 (representing Short wave Infra-red)

5. The composite image generated will be interpreted as follows

Example

Interpretation:

The image generated represents Greater Mumbai

The dark blue colour represents fresh water

Lighter blue represents salt water

Brighter red colour indicates vegetal cover

Darker shades of red indicate mangroves

Grey color indicates settlement zones

Result: Satellite images were studied



QUESTIONNARE:

1. How is remote sensing used in civil engineering?

2. How do you compare the image generated with that from google earth?

3. What do you understand by multispectral images?

4. Which bands are used in creating colour composite images?

5. Describe the significance of infra-red, visible and microwave bands and their applications

in civil engineering



Surveying Project 1 Date:

CONTOURING USING TACHEOMETER

Aim: To plot contours representing topography by radial method.

Instruments: Tacheometer, Tripod, Plumb Bob, staff.

Course Outcome: Draw and interpret contour plots.

Theory: Tacheometric method is an indirect method of contouring, adopted for contouring of

very steep hills.

Procedure: i) Set up the tacheometer at the top of the steep hill. Tacheometer is a theodolite fitted with

stadia diaphragm. The stadia diaphragm has three horizontal parallel hairs instead of one as

found in a conventional cross hair diaphragm.

ii) With the help of a tacheometer it is possible to determine the horizontal distance of the

point from the telescope as well its vertical level.

iii) The steep hill is surveyed at three levels – the base of the hill, the mid-level of the hill and

the top level of the hill.

iv) Using the tacheometer reading are taken all around the hill at equal angular intervals on all

these three levels.

v) The radial plot thus obtained is worked in the office to interpolate points of equal elevation

for contour mapping.



OBSERVATION TABLE

Sta

tio

n P

oin

t

Sta

ff P

oin

t

Bea

ring

Hei

ght

of

inst

rum

ent

Stadia Readings

Hori

zonta

l

angle

V

erti

cal

angle

Dis

tance

m

R.L

. m

Rem

arks

Top

Axia

l

Bott

om

Result: Reduced levels of all the points were calculated and contours are plotted.



QUESTIONNAIRE:

1. What do you understand by the following terms?

a) Contour Map

b) Contour Line

c) Contour gradient

d) Contour Interval

e) Horizontal Equivalent

2. What is Object of preparing Contour Map?

3. Compare radial method to grid method of contouring

Date post:	26-Oct-2020
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EXPERIMENT NO: 1 DATE: TACHEOMETRIC CONSTANTS...long chord T1T2 (L) given by the formula, Mark T1 on...

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