78. The normal longitudinal overlap is generally kept
79. The net ground area of a vertical photograph 20 cm x 20 cm on scale 1: 10,000 having overlaps 60% and 30%, is
A. 0.50 sq km
B. 0.56 sq km
C. 0.60 sq km
D. 0.64 sq km.
80. If 16 flight lines are run perpendicular 4enemdicular to an area 30 km wide, their spacings on a photographical map on scale 1: 50,000, will be
A. 1 cm
B. 3 cm
C.(e) 5 cm.
81. If the general ground level of any area is 10% of the flying height, the principal points may be used as the centres of radial directions for small scale mapping even in tilted photograph up to
82. In a truly vertical photograph,
A. principal point coincides the isocentre
B. iso-centre coincides the plumb point
C. plumb point coincides the principal point
D. all the above.
83. Pick up the incorrect statement from the following :
A. In truly vertical photographs without relief angles are true at the plumb point
B. In tilted photographs without relief, angles are true at the iso-centre
C. In tilled photographs with relief, angles are true at the principal point.
D. none of these,
84. The distance between the minor control point and the principal point should be equal to
A. base line of the left photograph of stereo pair
B. base line of the right photograph of stereo pair
C. sum of the base lines of stereo pair
D. mean of the base lines of the stereo pair.
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