SOLUTION ON PHOTOGRAMMETRY PROBLEMS PART 1

Examples

1) The scale of an aerial photograph is 1 cm = 100 m. The photograph size is 20cm x 20cm. Determine the number of photographs required to cover an area of 100 sq. km if the longitudinal lap is 60% and the side lap is 30%.

Solution.

Here                l = 20 cm  ;  w = 20 cm  ;  P₁ = 0.60 ; P_w = 0.30

                         

 The actual ground length covered by each photograph is

                        L = (1 – P_l) sl = (1- 0.6) 100 x 20 = 800 m = 0.8 km

Actual ground width covered by each photograph is

                        W = (1 – P_w) sw = (1 – 0.3) 100 x 20 = 1400 m = 1.4 km

 Net ground area covered by each photograph is

                        a = L x W = 0.8 x 1.4 = 1.12 sq. km

hence number of photographs required is

                       

2) The scale of an aerial photograph is 1cm = 100 m. The photograph size is 20cm x 20xm. Determine the number of photograph required to cover an area 10 km x 10km, if the longitudinal lap is 60% and the side lap is 30%.

Solution

Here                L₁ = 10 km  ; L₂ = 10 km

  Number of photographs in each strip is given by

           

Number of flight lines required is given by

           

Hence number of photographs required will be           

The spacing of the flight lines would be 10/9 = 1.11 km and not 1.4 as calculated theoretically in the previous example.