semiPhoto Flashcards
A spatial view can be obtained with naked eyes for a distance up to
640m
which of the following is an appropriate scale of an air photograph
1cm = 100m
The focal length of an aerial camera is 12.5cm and the exposure station was 2500m above datum. The scale of the photograph is
1cm=200m
An aircraft Flying at a ground speed of 180km/h. The focal length of the canera is 159mm. The longutudinal coverage of the ground is 900m. Ehixh one is the exposure interval.
18s
if the distance of the image of a point A from the isocentre, on a tilted photograph is 15.6mm and the same distance is equal to 14.9mm on a vertical photograph, tilt distortion is
0.7mm
A vertical photograph was taken at a altitude of 1500 MSL if the focal length of the camera is 20m, the scale of photograph for a terrain lying at sn elevation of 500m is
1:50
Twi consecutive photographs were taken with an overlap of 55% and the print size was 22.5cm X 22.5cm for both the photographs. All the conditions were same and the scale of the photograph was 1cm=200m. The lenght of air base is
2.025km
A vertical photograph of a chimney was taken from an elevation of 500m above MSL. The elevation of the base of chimney was 250m. If the relief displacement of the top of chimney was 51.4mm and the radial distance of the image of the top of the chimney was 110mm, the height of the chimney is
116.82
In an aerial photogrammetric survey, if the exposure interval is 20 seconds to cover a ground distance of 100m between exposure, what would be the ground speed of the aircraft?
180km/hr
What is the actual ground area covered by a 20cm X 20cm size vertical aerial photograph, at an average scale of 1cm = 200m having 60% forward overlap 0% side overlap?
4.48 km2
A tower appears in two successive photographs taken at an altitude of 4000m above datum. The focal length of the camera is 160mm, the length of the air base is 300m. The parallax for the top and bottom of the tower are 72mm and 63 mm respectively. The height of the top of the tower above its bottom is nearly
95m
A road section of length 1 km scales 8cm on a vertical photograph. The focal length of the camera is 160mm. If the terrain is fairly level, then the flying height will be
2000m
The distance of images of the top and bottom of a tower, in a print taken from H above ground, are D and d from principal point, respectively. The height is then
H(D-d)/D
If f is the focal length of camera and t is the tilt angle, distance of the photo nadir from the principal point will be
t tan (theta)
If the net length covered by each photograph is 1.2km and the length of strip os 20km, the number of air photographs required are
18
aerial photographs are
perspective projections
The perspective and orthographic projections produce similar images on a
vertical photograph
The vertical axis of a camera is inclined by 1degrees to the vertical to cover large number of details while photographing from air. The resulting photograph will be a
oblique photograph
Vertical photographs do not replresent the true plan of the ground because of
ground relief
Which of the following coincides with the point of intersection of x and y axes of an aerial photograph?
Principal point
The scale if vertical photographs of a flat terrain, with a variation in the flying altitude, will be
non-uniform
On a vertical photograph the relief displacement is always radial from
principal point
Ground control points are established in aerial photogrammetry to control
scale
When the effect of wind is not considered during flight planning, the result is a
drift
When the aerial camera cannot be kept square with the direction of flight, the result is a
crab
The spatial view of a photographed terrain canbe has through
stereoscope
The elevation of the objects on air photographs can be measure because of the
stereoscopic fusion
In aerial photogrammetry, map details are plotted by
All of the above
slotted template method of map plotting in aerial survey is
mechanical method
Rectification pf aerial photographs is required for
Both a and b
In air photogrammetry the desired overlap is obtained by
intervalometer
For reconnaissance of preliminary location of highways, the aerial photographs used should preferably be
oblique
Aerial photograph in which the horizon is included is known as
tilted
Tilt displacements are radial about
isocentre
In a tilted photograph, the relief displacement is radial from the
nadir point
Parallax bar is used to measure
parallax difference
An example of air-photo interpretation key is
elimination key
Observation of two photographs simultaneously is called
stereoscopy
The relief displacement on an air photograph decreases with the
both B and C
Pick out the correct statement for relief displacement in aerial photographs
It is positive and radially for points above datum
Overlap in arrial photograph is necessary
for all the above
The object of photo-interpretation is
all of the above
photo- interpratation depends upon
All of the above
Pick out the correct statement for picture control points in aerial photographs
these do not have corresponding ground control points
Pick out the incorrect statement regarding mosaics in aerial photogrammetry
uncontrolled mosaics are obtained by rectified air photographs
an aerial photographs is taken at a flying height of H1 metre above the datum. The focal length of the camera was f cm and the average scale was 1cm=H2 metre such that H2>H1. This implies that
the photograph terrain lies at an elevation (H2-H1) below the datum
(i) The horizon point of an aerial photograph ABCD lies on the photo itself.
(ii) The photograph ABCD is a high oblique photograph
State whether
(ii) follows from (i)
in a tilted photograph
the downward half has larger scale
(i) In aerial photograph the principal and nadir points councide,
(ii) The isocentre also cooncide with the other two points
Conclusion: It is a truly vertical photograph
State whether
the conclusion can be deduced only if both (i) and (ii) are given
An observer views two points A and B such that the angle of parallax of B is greater than that of A. Therefore,
object B is nearer the observer
The difference of parallax for a given difference in elevation is independent of
All of the above
Which of the following is true for a tilted photograph?
The scale is uniform for all the points on a line perpendicular to the principal line
Which of the following is true
Both a and b
Homologous points are
corresponding points on the ground and the photograph
Setting off the ‘proper principal distance’ in the projectirs of projection stereoplotters is a procedure for which one of the following
evaluating the digital terrain model
The basic requiremnts of an aerial camera is
All of the above
(i) Every point on an aerial photograph is displaced from its true orthographic position
(ii) amAerial photographs show perspective view
State whether
both (ii) and (ii) are true and (i) follows from (ii)
Pick out the correct statement
both (i) and (ii) are true
Pick out the correct statement for aerial photogrammetry
both (i) and (ii) are correct
