GATE CE 2022: Transportation Engineering & Surveying Quiz #14
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Which one of the following statements are true?
i. Terrestrial photography gives mostly oblique photographs
ii. Aerial photography always gives perfectly vertical photographs
A camera of focal length 18 cm is used to photograph a building of height 27m from a distance of 150 m. What is the height of the building on the photograph in millimeters?
A camera of focal length 15 cm is used to take images of the ground at an altitude of 2100m from the mean sea level. The size of the photograph is 25 cm × 25 cm. The ground is at 300 m from the sea level and the area of the ground is 108 sqkm. If the longitudinal overlap is 60% and the side lap is 40%, find the number of photographs required.
In a pair of overlapping photographs, the mean distance between two principal points both of which lie on the datum is 6.375 cm. at the time of photography, the air craft was 600 m above the datum. The camera has a focal length of 150 mm. in the common overlap a tall chimney 120 m high with its base in the datum surface is observed. Determine the difference of parallax for top and bottom of chimney.
The coordinates of two points A and B on a photograph are given as follows. The focal length of the camera was 20 cm and its altitude above B was 750 m. If the elevations of A and B are 200 m and 250 m respectively from the sea level, what will be the length of the straight line drawn from A to B in meters.
Assertion (A): Horizontal distance between two points on a vertical photograph can be calculated directly by measuring the distance on the photo and multiplying it with the scale.
Reason (R): Photo distance is the product of scale and ground distance.