PS Photogrammetry & Remote Sensing 3

Question 1

The exposure station (perspective center) in aerial photogrammetry is defined as:

Accepted Answer

The spatial position of the camera's front nodal point at the instant of image capture

Answer

The exposure station is the 3D spatial location of the camera's front nodal point at the moment of exposure; all image-forming rays are assumed to pass through this single point.

Question 2

In stereoscopic photogrammetry, x-parallax measurements are used primarily to:

Accepted Answer

Determine ground elevations from the stereo photo pair

Answer

The difference in x-coordinates of a conjugate point between the left and right photographs (x-parallax) is directly proportional to the point's elevation above the datum, enabling precise height determination from stereo pairs.

Question 3

An Inertial Measurement Unit (IMU) integrated with GPS/GNSS in an airborne photogrammetric system primarily provides:

Accepted Answer

Direct measurement of aircraft roll, pitch, and yaw angles for each photo's exterior orientation

Answer

The IMU records angular orientation (roll, pitch, yaw) at high frequency; combined with GPS-derived position, this direct georeferencing approach determines the exterior orientation of each photo without relying solely on ground control points.

Question 4

Sidelap between adjacent aerial flight strips is typically maintained at what percentage for standard mapping projects?

Accepted Answer

20–30%

Answer

A sidelap of 20–30% is the standard specification for aerial mapping; this ensures complete ground coverage with no gaps between strips while keeping the total number of flight lines and mission cost manageable.

Question 5

Structure from Motion (SfM) photogrammetry is distinguished from classical photogrammetry primarily by its ability to:

Accepted Answer

Simultaneously reconstruct 3D scene geometry and solve for camera positions from unordered overlapping image sets

Answer

SfM uses automatic feature detection and matching across many overlapping images to jointly solve for camera poses and sparse 3D point positions, requiring no predefined camera locations or calibration—ideal for drone-based surveys.

(PS) Professional Licensed Surveyor Practice Test

(PS) Professional Licensed Surveyor Practice Test

PS Photogrammetry & Remote Sensing 3