Uneven Lies: Uphill, Downhill, Ball Above and Below Feet
Applies 3D D-Plane coordinate transformations to terrain slopes, analyzing how pitch and roll alter attack angle, dynamic loft, delivered lie, and ball curvature.
diagnostics · 7 min · EDUCATIONAL_APPROX
A slope changes the reference frame
An uneven lie changes the relation between the ground plane, the golfer's setup, and world vertical. The app exposes those effects as educational scenario controls. Its setup and delivery adjustments are assumptions, not measurements of how every golfer adapts.
Uphill and downhill lies
A slope along the target line can change stance, delivered loft, attack angle, and strike quality. The direction and size of those changes depend on the player and club. The app's example values are scenario inputs; they are not vendor rules or experimentally calibrated coefficients.
Ball above or below the feet
A sidehill lie changes the club's roll relative to the ground. In the model, a delivered-lie change rotates the face normal. For a right-handed club at zero face angle, the current transform gives:
$\Delta\phi_{\text{face}} = -\arctan(\sin(\Delta_{\text{lie}})\tan\delta_{\text{loft}})$
Positive lie deviation is toe-up in this convention. The effective face azimuth therefore shifts left for that specific case; toe-down reverses the sign. Terrain alone does not determine a golfer's start direction or curve, because the player can change aim, posture, strike, and delivery.
Treat the presets as controlled illustrations. Do not read their outcomes as an on-course prediction or a universal instruction to aim away from the target.