tactile op• Data kinds: image → image
• Call: fullseye.apply(img, "tac_shear_field", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
In-plane shear proxy from the 2-D structure tensor (Foerstner / Bigun-Granlund orientation coherence). The tensor `J = G_sigma(grad v * grad v^T) has eigenvalues l1 >= l2, and the coherence (l1-l2)/(l1+l2) = sqrt((J11-J22)^2 + 4*J12^2) / (J11+J22) is 1 where the gel texture is stretched into a single dominant orientation (as it is under tangential/shear load) and 0 where it is isotropic. The result is additionally weighted by the tensor trace (gradient energy) so that texture-free, un-contacted gel stays dark instead of amplifying noise orientation. a = tensor integration sigma (0.6..4.6), b` = output gain (0.5..2.5). Output clipped to [0,1], HxW; a constant frame has zero gradient energy and yields an all-zero shear field.
• Sample-data catalog (download URLs / licences) — 2-D uses skimage.data (BSD/public domain) plus synthetic images; 3-D lists download URLs for real data sources (Stanford, PDS, …).
• Operator provenance and references — the sources of the research/methods this op family came from.
• sim2real_and_alife — py -3.11 examples/sim2real_and_alife.py
image as input)identity · gaussian · mean_box · bilateral · unsharp · median · min_filter · max_filter
tactile)tac_contact_mask · tac_height_from_shading · tac_surface_normal · tac_pressure_proxy
*Provenance: ops.py — 2D operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.