AOI Perturbation Sensitivity Analysis

The sensitivity engine applies declared geometry changes, remaps observations, recomputes AOI features, and optionally reruns the same user-supplied model.

Supported operations

• dilation and erosion;
• x-only, y-only, and combined x/y translation;
• reproducible uniform jitter;
• anisotropic x/y expansion;
• margins in pixels or degrees;
• rectangles and polygons.

Convex polygons support true geometric offsetting. Concave dilation/erosion is rejected instead of being silently convexified or approximated.

grid = ep.create_aoi_perturbation_grid(
    dilations=[0.25, 0.50, 1.00],
    erosions=[0.25],
    translations_x=[0.50],
    translations_y=[0.50],
    translations_xy=[(0.25, -0.25)],
    unit="deg",
    screen_width_px=1024,
    screen_height_px=768,
    viewing_distance=60,
    physical_screen_size=(53.1, 29.9),
)

Failure behavior

translations_xy accepts one or more explicit x/y pairs; NumPy arrays and other iterable inputs are accepted without truth-value coercion. Branches that collapse or invalidate geometry are recorded as failed. Screen-edge behavior is also explicit through warn, clip, error, or allow. Jitter retains its seed in the branch specification.

Run the worked example after reading Pixels versus Degrees of Visual Angle.