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The prismoid is a solid which has end faces along parallel planes.

The end faces may be of different polygons. The longitudinal faces

are planes extending between the end planes

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A

BF

E

D

C

A

B

C

D

E

F

In this method, the plan table is set up

at only one station and the points tobe located are located by drawing

rays in the corresponding directions

and measuring the distance between

the stations and the instrument

station. This method is used when the

area to be surveyed is small and can

be commanded from a single station.

In this method, the plan table is set up

at only one station and the points tobe located are located by drawing

rays in the corresponding directions

and measuring the distance between

the stations and the instrument

stati

on. This method is used when the

area to be surveyed is small and can

be commanded from a single station.

OO

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Steps to be followed

A point O is selected in the field from which all the stations to be plotted

are visible.

Step 1

A point O is selected in the field from which all the stations to be plotted

are visible.

A point O is selected in the field from which all the stations to be plotted

are visible.

Step 1

Set up the plane table at the point O and plot a point O which willrepresent the ground station O on the sheet.

Step 2

Set up the plane table at the point O and plot a point O which willrepresent the ground station O on the sheet.

Set up the plane table at the point O and plot a point O which willrepresent the ground station O on the sheet.

Step 2

Level the plan table primarily with the help of tripod legs and placing the

level tube at the four corners of the sheet and at the centre of the sheet.

Step 3

Level the plan table primarily with the help of tripod legs and placing the

level tube at the four corners of the sheet and at the centre of the sheet.

Level the plan table primarily with the help of tripod legs and placing the

level tube at the four corners of the sheet and at the centre of the sheet.

Step 3

Mark the direction of the magnetic meridian on the right hand top corner

of the sheet indicated with the help of trough compass.

Step 4

Mark the direction of the magnetic meridian on the right hand top corner

of the sheet indicated with the help of trough compass.

Mark the direction of the magnetic meridian on the right hand top corner

of the sheet indicated with the help of trough compass.

Step 4

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Centering the alidade at O, sight the stations ABCDEF to be plotted anddraw rays or lines along the fiducial edge of the alidade.

Step 5

Measure the distances OA, OB, OC, OD, OE and OF with the help of a

chain or tape and plot them along corresponding rays on the sheet tosome convenient scale.

Step 6

Join ABCDEF to have the outline of the traverse

Step 7

Centering the alidade at O, sight the stations ABCDEF to be plotted anddraw rays or lines along the fiducial edge of the alidade.

Centering the alidade at O, sight the stations ABCDEF to be plotted anddraw rays or lines along the fiducial edge of the alidade.

Step 5

Measure the distances OA, OB, OC, OD, OE and OF with the help of a

chain or tape and plot them along corresponding rays on the sheet tosome convenient scale.

Measure the distances OA, OB, OC, OD, OE and OF with the help of a

chain or tape and plot them along corresponding rays on the sheet tosome convenient scale.

Step 6

Join ABCDEF to have the outline of the traverse

Join ABCDEF to have the outline of the traverse

Step 7

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1

2

3

4

A Ba b

ab

1 2 3 4

This method is used

when the points to

be located are at

larger distances. In

this method, points

are fixed by theintersection of rays

drawn from two

different instrument

stations. The line

joining the

instrument stations

is called base line.

This method is

suitable for locating:

This method is used

when the points to

be located are at

larger distances. In

this method, points

are fixed by theintersection of rays

drawn from two

different instrument

stations. The line

joining the

instrument stations

is called base line.

This method is

suitable for locating:

1. Distance cannot be measured

precisely with a chain or tape due to

large distance

2. Inaccessible point

3. Interior details

4. Points which will be used asinstrument stations subse uentl

Base LineBase Line

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Steps to be followed

Select two points A and B on the field such that the points to be plotted

are visible from these two points. The line joining AB is called base line.

Step 1

Select two points A and B on the field such that the points to be plotted

are visible from these two points. The line joining AB is called base line.

Select two points A and B on the field such that the points to be plotted

are visible from these two points. The line joining AB is called base line.

Step 1

Set up the plane table at A. Locate the corresponding point a on the

sheet which represents ground station A with the help of a plumbing fork

and level the plane table.

Step 2

Set up the plane table at A. Locate the corresponding point a on the

sheet which represents ground station A with the help of a plumbing fork

and level the plane table.

Set up the plane table at A. Locate the corresponding point a on the

sheet which represents ground station A with the help of a plumbing fork

and level the plane table.

Step 2

Centering the alidade at a, sight the station B and draw rays along thefiducial edge of the alidade. Accurately measure the distance between A

and B and mark the corresponding point b along the previously drawn

ray in the sheet to some convenient scale.

Step 3

Centering the alidade at a, sight the station B and draw rays along thefiducial edge of the alidade. Accurately measure the distance between A

and B and mark the corresponding point b along the previously drawn

ray in the sheet to some convenient scale.

Centering the alidade at a, sight the station B and draw rays along thefiducial edge of the alidade. Accurately measure the distance between A

and B and mark the corresponding point b along the previously drawn

ray in the sheet to some convenient scale.

Step 3

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Centering alidade at a, sight the stations 1, 2, 3 and 4 and draw rays

along the fiducial edge of the alidade.

Step 4

Centering alidade at a, sight the stations 1, 2, 3 and 4 and draw rays

along the fiducial edge of the alidade.

Centering alidade at a, sight the stations 1, 2, 3 and 4 and draw rays

along the fiducial edge of the alidade.

Step 4

Shift the plane table to instrument station B centering b over ground

station B. Level the plane table with the level tube.

Step 5

Shift the plane table to instrument station B centering b over ground

station B. Level the plane table with the level tube.

Shift the plane table to instrument station B centering b over ground

station B. Level the plane table with the level tube.

Step 5

Orient the plane table by centering the alidade at b and turning the plane

table until the line of sight strikes A. Clamp the board.

Step 6

Orient the plane table by centering the alidade at b and turning the plane

table until the line of sight strikes A. Clamp the board.

Orient the plane table by centering the alidade at b and turning the plane

table until the line of sight strikes A. Clamp the board.

Step 6

Centering alidade at b, sight the ground stations 1, 2, 3 and 4 and draw

corresponding rays along the fiducial edge. The intersection of these

rays with the respective rays drawn from station Awill give the desired

positions of stations 1, 2, 3 and 4

Step 7

Centering alidade at b, sight the ground stations 1, 2, 3 and 4 and draw

corresponding rays along the fiducial edge. The intersection of these

rays with the respective rays drawn from station Awill give the desired

positions of stations 1, 2, 3 and 4

Centering alidade at b, sight the ground stations 1, 2, 3 and 4 and draw

corresponding rays along the fiducial edge. The intersection of these

rays with the respective rays drawn from station Awill give the desired

positions of stations 1, 2, 3 and 4

Step 7

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A B

C

D

E

ac

a bb

a b

c

d

a b

c

d

e

a b

c

d

e

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