Cortical Sampling: Uniform vs Polar vs Isotropic

How V1 tiles the visual field — and why cell shape matters

Uniform (retinal)
Polar (fixed spokes)
Isotropic (FOVI-derived)
Square in cortex (ratio ~1.0)
Stretched (ratio > 1.5)
Compressed (ratio < 0.7)
Fovea (ring 0)
30
24
15°
Left: Uniform retinal grid — equal-area cells, what the world looks like before the cortex remaps it. Center: Polar grid with fixed spoke count — the naive approach. Outer cells stretch into wide arcs (red = anisotropic). Right: Isotropic grid from Blauch, Alvarez & Konkle (2026) — spoke count per ring chosen so each cell is approximately square in cortical coordinates (green = isotropic).