Feb 26, 2016

Feb 26, 2016

Feb 26, 2016

# Principal Method of Terrestrial Photogrammetry

/ On: Jun 18, 2017 /

The principal is exactly similar to plan table surveying, it may be stated as βThe position of the object with ref to the base line is given by the intersection of the rays drawn to it form each end of the base lineβ In plane tabling most of the work is executed in the field while in this method it is done in the office. The principal is explained as follows

C and D = Camera stations.

CD = Base line of length βBβ

CE and DE = Position of vertical plane of collimation. and

B = Observed vertical angles which the vertical plane of collimation make with base line at C and D.

M = pt to be located, which is shown as βmβ in both the photographs.

X1 and Y1 = Coordinates of βMβ on ptβCβ

Watch a Video on How to Apply Terrestrial Photogrammetry Method

X2 and Y2 = ----------------------------βDβ

F = focal length of camera lens

(Photograph from βCβ) (Photograph from βDβ)

## Method of location PT βMβ:

Pt βMβ may be plotted graphically or analytically.

### Graphical Method :

• First plot the base line to the given scale
• Draw CE making an angles of β β wide CD with the help of a protector.
• Similarly draw DE making an angle of B with BE.
• On CE mark the pt βeβ at a distance equal to fine font of βCβ. Similarly setoff a distance βDeβ equal to βfβ along DE in front of D as shown.
• To these pts and βeβ draw lines right angles ot CE and DE respectively measure βemβ equal to X1and To X2 along these perpendicular lines on the same side as on the photographs. (Her they are measured on ht left of CD and DE)
• Join βCMβ and βDMβ and produce them so as to meet at βMβ which gives required position of βMβ on Plane

### To determine the level of PT βMβ

• Measure βyβ which gives the height of βmβ above the horizontal hair. Rise of the ray from βmβ to the center of the object glass is equal to βyβ in a horizontal dist
• Measure the distance βCMβ to the scale on the plane.
• The height βHβ of βMβ above the horizontal Plane of collimation at βCβ is given by Knowing the reduced level (RL) of horizontal plane of collimation, the RL of M may be obtained as R.L of M= R.L of horizontal plane of collimation at 'C' is given by:

### Field Work:

The field work of terrestrial photographic surveying consists of

• Reconnaissance
• Triangulation
• Camera work