Foveated Rendering for Mobile XR — 2D Heatmap Simulation

Gaze / Eye Tracker

Foveal radius (θ₁) 6°

Blend width (θ₂−θ₁) 10°

Periphery resolution scale 0.20

Saccade speed 1.0×

Grid density 28

Render Cost

Shaded px / frame

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GPU cost saved

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Effective res.

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Mode

Foveated

How it works

Mobile XR headsets (Quest, ARKit/ARCore passthrough devices) track the eye's gaze point g(t) with an inward-facing IR camera and render three concentric zones around it, defined by angular eccentricity θ from the gaze direction:

R(θ) = 1                              for θ ≤ θ₁   (foveal — full res)
R(θ) = 1 − (1−s)·(θ−θ₁)/(θ₂−θ₁)       for θ₁ < θ < θ₂ (blend)
R(θ) = s                              for θ ≥ θ₂   (periphery — scale s)

Human visual acuity itself falls off roughly as 1/θ away from the fovea (cone density drops ~50% by 5° eccentricity), so the eye cannot tell the periphery apart from full resolution even though far fewer pixels are shaded there. Per-frame GPU pixel cost is the resolution-weighted area integral:

Cost = ∫∫ R(θ(x,y))² dA   over the frame
Saved = 1 − Cost / (W·H)
EffRes = √Cost   (RMS linear resolution scale — cost scales with the square
                  of linear resolution since it applies along both axes)

This 2D simulator renders the same falloff as a live top-down resolution heatmap: the frame is a grid of cells, each shaded from dark (heavily downsampled periphery) to bright blue (full-res fovea) by R(θ) at its own eccentricity from the gaze point, with cell size itself shrinking toward the periphery to make the density drop visible directly. A second panel plots R(θ) itself as a curve against eccentricity in degrees, with the foveal/blend boundary lines moving live as you drag the sliders. Toggle "uniform" to flatten R(θ) to 1 everywhere and watch the cost readout jump back to 100%.

Auto saccade — the gaze point jumps between fixation targets on a timer, mimicking real saccadic eye movement.
Manual (drag) — drag on the heatmap to steer the gaze point yourself.
Foveal radius / blend width / periphery scale — the three R(θ) zone parameters above.
Grid density — how many cells the heatmap is divided into (does not change the physics, only the visualization resolution).

Drag on the heatmap to move the gaze point (switches to Manual mode)

Foveal zone (full res) Gaze point Periphery tile

R(θ) resolution falloff vs. eccentricity (°)

Foveated Rendering for Mobile XR — 2D Simulation