Certified Photogrammetrist Stereo Compilation & 3D Modeling

Question 1

What is the 'y-parallax' in a stereopair, and what does excessive y-parallax indicate?

Accepted Answer

Residual vertical displacement after relative orientation; it indicates incomplete relative orientation

Answer

Y-parallax is residual vertical displacement of conjugate points in a stereopair after relative orientation; excessive y-parallax indicates that the relative orientation is incomplete or incorrect.

Question 2

In stereo compilation, what does 'absolute orientation' accomplish?

Accepted Answer

It scales, rotates, and positions the stereomodel into a real-world coordinate system using ground control

Answer

Absolute orientation transforms the relatively oriented stereomodel (which exists in an arbitrary coordinate system) into real-world coordinates using ground control points.

Question 3

What is 'x-parallax' used for in stereo photogrammetry?

Accepted Answer

Measuring elevation differences between points in a stereopair

Answer

X-parallax (the horizontal displacement between corresponding points in a stereopair) is directly related to the elevation of those points and is the fundamental measurement used for height determination.

Question 4

What is a 'floating mark' in analogue or softcopy stereo compilation?

Accepted Answer

A stereoscopic measuring mark that appears to float at a selected elevation within the stereomodel

Answer

A floating mark is a stereoscopic measuring reticle that the operator perceives as resting on the terrain surface when the parallax is correctly set, used to measure or compile terrain features.

Question 5

What are the six elements of exterior orientation for a single photograph?

Accepted Answer

X, Y, Z (position of perspective center) and ω, φ, κ (three rotation angles)

Answer

Exterior orientation consists of six parameters: three for the position of the perspective center (X₀, Y₀, Z₀) and three rotation angles (omega ω, phi φ, kappa κ) defining the camera's attitude.

Certified Photogrammetrist Practice Test

Certified Photogrammetrist Practice Test

Certified Photogrammetrist Stereo Compilation & 3D Modeling