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Question 1

Definition of photogrammetry

Answer 1

Science of obtaining informations from photographs

Question 2

2 major area of photogrammetry specialization

Answer 2

Metrical (determining spatial information)

Interpretative (recognizing objects)

Question 3

What is the most frequently applied approach in surveying (photogrammetry)?

Answer 3

Metrical photogrammetry using aerial photographs (photo from aircraft)

Question 4

Advantages of photogrammetry

Answer 4

Fast collecting spatial data

Low cost

Easy obtaining topographic details, especially in inaccessible area

Reduced the possibility losing details in data

Question 5

The most used aerial cameras in metrical photogrammetry

Answer 5

Single-lens frame cameras

Exposing the entire frame at the same time through a lens held at fixed distance

Ex: Digital Mapping Camera (DMC)

Question 6

Single lens frame camera components

Answer 6

Shutter and diaphragm: control interval and time the light passes the lens

Lens: gathers incoming light rays and bring them to the focal plan

Focal plane: surface where the film lies (sometimes replaced by Charge-Coupled Device in digital cameras

Question 7

Types of aerial photographs

Answer 7

Vertical (camera axis aimed vertically downward)

Oblique (seldom used in metrical surveying)

Question 8

What is not true orthographic projection but isna perspective views?

Answer 8

Vertical photographs

Question 9

Relief displacement

Answer 9

The displacement of an object’s image point from its origin location caused by the object’s relief.

Question 10

Relief displacement formula

Answer 10

RD =rh/H

r = the distance between the principal point to the point of relief displacement

h = the height of the tower

H = the flying height above the datum

Question 11

Building radially outward to the principal point (magnitude increases with greater distance)

Answer 11

Relie displacement

The bigger the elevation difference,the bigger the relief displacement

Question 12

Apparent displacement of the position of an object due to the displacement in the point of observation

Answer 12

Parralax

Question 13

Points closer to camera (the higher elevation), will……

Answer 13

Move faster and have greater parallaxes

Question 14

Application of parallax

Answer 14

Stereoscopic viewing

Question 15

What is stereoscopic viewing

Answer 15

Placing two overlapping photos on the table and using a stereoscope (left eye see left image, so do right eye)

Question 16

Coordinate systems of analytical photogrammetry (types and goal)

Answer 16

Image coordinates (xy) - if digital, pixel coordinates (rc)

Image space coordinates (xyz)

Ground space coordinates (XYZ)

goals: to find real word position (XYZ) from filmed photo (xy)

Question 17

Interior and exterior orientation

Answer 17

Interior orientation: defines the internal geometry of a camera (based of focal length)

Exterior orientation: defines the position and orientation of the camera (based on the coordinates)

Question 18

The collinearity condition

Answer 18

Exposure center, image point, ground point should lie in one straight line (applied to all)

Question 19

Based on …… and … XYZ can be known and 3D model can be established

Answer 19

Collinearity condition and all the corresponding equations