Stereo basal plane and relative orientation — core facts Which statements about the basal plane and relative orientation in a stereo pair are correct?

Introduction / Context:
Relative orientation is a cornerstone of analytical and digital photogrammetry. It restores the correct angular relationship between two photographs so that homologous rays intersect consistently in 3D, creating a stereo model free from Y-parallax. The basal plane concept helps visualize the linkage between each ground point and the two perspective centres.

Given Data / Assumptions:

• Two photographs form a stereo pair with known/unknown relative orientation.
• Y-parallax refers to parallax perpendicular to the flight direction in the model space.
• Five-parameter model (or equivalent) is sufficient to remove Y-parallax at five well-chosen points.

Concept / Approach:
The basal plane associated with a given ground point is the plane containing that point and both perspective centres. Every conjugate point pair defines such a plane. Relative orientation aims to reconstruct the correct geometry between the photos so that these basal planes are consistent; practically, this is tested by eliminating Y-parallax at several control points (classically five) distributed over the model.

Step-by-Step Solution:

Verification / Alternative check:
In analytical plotting and modern software, relative orientation parameters are solved by least squares using many tie points; the five-point rule reflects the minimal degrees of freedom.

Why Other Options Are Wrong:

• Each statement is correct; therefore, “All of the above” is appropriate.

Common Pitfalls:
Confusing relative orientation (between photos) with absolute orientation (to ground coordinates); treating Y-parallax removal at a few points as sufficient without checking residuals across the model.

Final Answer:
All of the above