Feature Request: Curve-Constrained Vertical Warping for Geometric Correction

[godinlu]

Feature Request: Curve-Constrained Vertical Warping for Geometric Correction

Context

In the current KH-9 image processing pipeline, mosaicking introduces significant geometric distortions (notably vertical bowing and shear artifacts). To correct these distortions, we currently rely on a combination of RANSAC-based boundary detection (top and bottom edges) and a TPS-based or blockwise remapping strategy.

However, this approach can be overly flexible and computationally heavy, and may introduce unnecessary deformation artifacts outside the region of interest.

Proposed Feature

Implement a Curve-Constrained Vertical Warping (CCVW) transformation model.

This method uses two boundary curves (top and bottom) to define a normalized vertical coordinate system, and performs a deterministic, monotonic remapping between source and target geometry.

Advantages Over Current Approach

Compared to TPS:

• Reduced computational cost
• No global system solving
• More stable in cases with quasi-1D deformation structure
• Better interpretability

Compared to affine models:

• Spatially varying deformation along x-axis
• Captures non-linear bowing effects typical of KH-9 mosaicking

Exemple of this transformation on regular grid

Note : this case is just to illustrate the effect transformation so the 2 lines are really curved but usually tranformation will be softer.

Curve-constrained Vertical Warping

Thin plate spline