Aerial Triangulation & Bundle Adjustment Flashcards

What is the 'sigma naught' (σ₀) in bundle adjustment output?

Answer: The standard deviation of unit weight, indicating overall solution quality

Sigma naught (σ₀) is the standard deviation of unit weight from the least-squares solution, providing an overall indicator of the internal consistency and quality of the adjustment.

Strip deformation in aerial triangulation typically appears as what type of systematic error?

Answer: A 'bow' or 'banana' shape bending along the flight strip

Strip deformation manifests as a systematic bow or banana-shaped bending along a flight strip, caused by accumulated errors in relative orientation between successive stereomodels.

What role does the 'datum' play in aerial triangulation?

Answer: It defines the coordinate system to which the solution is referenced

The datum defines the coordinate reference system (e.g., NAD83, WGS84) to which the triangulated block is tied through the ground control points.

In photogrammetric AT, what is a 'check point' (independent check point)?

Answer: A ground-surveyed point withheld from the adjustment and used only to verify accuracy

A check point is a ground-surveyed point intentionally withheld from the bundle adjustment and used afterward to independently verify the absolute accuracy of the solution.

What is the minimum number of ground control points needed to define a 3D datum (remove all datum defects) in a photogrammetric block?

Answer: 3 full 3D control points (not collinear)

Three non-collinear full 3D control points are the minimum needed to remove all seven datum defects (3 translations, 3 rotations, 1 scale) of a photogrammetric network.

What does 'over-determination' mean in the context of bundle adjustment?

Answer: Using more observations than unknowns, enabling a least-squares solution with redundancy

Over-determination means having more observations than unknowns, which provides redundancy and allows a least-squares solution that detects and distributes measurement errors.