Certified Photogrammetrist Stereo Compilation & 3D Modeling 3

Question 1

What is 'nadir' in aerial photogrammetry?

Accepted Answer

The point on the ground directly below the camera's perspective center (ground nadir), or its image (photo nadir)

Answer

Nadir refers to the ground point directly below the camera's perspective center (ground nadir) and its corresponding image location (photo nadir), which lies at the geometric center of a perfectly vertical photograph.

Question 2

What causes 'layover' in radar imagery, and can it affect photogrammetric products?

Accepted Answer

In radar, layover occurs when tall objects lean toward the sensor; in photogrammetry, the analogue is relief displacement

Answer

Radar layover occurs when tall objects appear to lean toward the sensor due to the near-range compression of elevated objects; the photogrammetric analogue is relief displacement, where objects appear displaced from their true position.

Question 3

What is the purpose of 'edge matching' in stereo compilation projects?

Accepted Answer

Ensuring that map features compiled in adjacent stereomodels connect seamlessly at model boundaries

Answer

Edge matching ensures that map features (roads, contours, building outlines) compiled in adjacent stereomodels align perfectly at the boundaries between models, maintaining topological continuity.

Question 4

What is 'stereoscopic exaggeration' in photogrammetric viewing?

Accepted Answer

The perceived amplification of vertical relief when the eye base is larger relative to the B/H ratio than normal human vision

Answer

Stereoscopic exaggeration is the perceived amplification of terrain relief when the base-to-height ratio exceeds that of normal human stereo vision (approximately 1/30), making slopes appear steeper than they are.

Question 5

In stereo compilation, what is the function of the 'model coordinate system'?

Accepted Answer

An arbitrary local 3D coordinate system defined by the relative orientation of a stereopair, before absolute orientation is applied

Answer

The model coordinate system is the arbitrary local 3D system defined after relative orientation of a stereopair, in which measurements can be made before the model is transformed to real-world coordinates through absolute orientation.

Certified Photogrammetrist Practice Test

Certified Photogrammetrist Practice Test

Certified Photogrammetrist Stereo Compilation & 3D Modeling 3