Certified Photogrammetrist Camera Calibration & Sensor Geometry 2

Question 1

What causes decentering (tangential) lens distortion?

Accepted Answer

Misalignment of optical elements from the optical axis within the lens system

Answer

Decentering distortion is caused by the physical misalignment or decentering of lens elements from the optical axis, producing an asymmetric distortion pattern.

Question 2

What is the purpose of a reseau grid (reseau plate) in analog aerial cameras?

Accepted Answer

To provide reference marks for detecting and correcting film deformation

Answer

A reseau grid contains precisely positioned crosses or dots imaged onto the film, allowing detection and correction of film deformation that may occur during processing or scanning.

Question 3

In digital aerial cameras, what component replaces the photographic film at the focal plane?

Accepted Answer

The CCD or CMOS image sensor

Answer

In digital cameras, the CCD or CMOS sensor array is positioned at the focal plane to capture light, directly replacing the role of photographic film as the image recording medium.

Question 4

In digital photogrammetry, pixel size of the sensor is most directly related to:

Accepted Answer

The ground sample distance (GSD)

Answer

Pixel size directly determines the ground sample distance (GSD) for a given flying height and focal length; GSD defines the smallest ground detail that can be resolved.

Question 5

Which camera calibration parameter corrects for non-orthogonality (shear) between the x and y axes of the image coordinate system?

Accepted Answer

Affinity (shear) parameter

Answer

The affinity or shear parameter corrects for non-orthogonality between the image coordinate axes, which can result from imperfect sensor geometry or digitizer scanning.

Certified Photogrammetrist Practice Test

Certified Photogrammetrist Practice Test

Certified Photogrammetrist Camera Calibration & Sensor Geometry 2