Tilt a pattern. Move its visible crossing.
IDWT works it out for a free line centred a distance h along a hidden spatial direction:
1. Along the line, x₄ = h + τ cos φ and x₁ = τ sin φ.
2. Our slice has x₄ = 0, so τ = −h/cos φ.
3. Substitute: x₁ = −h tan φ.
The crossing position follows directly from the tilt.
https://idwt-v2.github.io/papers/free-orientation-20261111.pdf