External Tools & Links

Standalone tools and pages hosted separately — each opens in a new tab.

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Visual Angle Calculator

Calculate the angular size of objects based on their physical dimensions and distance from the observer. Perfect for vision science, photography, and display calibration. For pixel-based calculations, see SR Research's Visual Angle Calculator

Visual Angle

10.29°
Radians
0.180
Arc Minutes
617.4'
Formula:
θ = 2 × arctan(size / (2 × distance))

Visual Representation (Side View)

Binocular Vision Convergence Visualizer

Explore how interpupillary distance and field of view affect binocular overlap. The eyes converge on the ball while FoV cones remain static. Drag the ball to see vergence angles change.

Vergence-Accommodation Conflict

VR headsets display images on a fixed LCD panel, so the eyes always accommodate (focus) at the same optical distance — infinity. But they must converge (aim) at whatever virtual object is nearby. Drag the fixation target to see how this mismatch grows as objects get closer, causing blur and eye strain. This is a fundamental limitation of current HMD optics.

Conflict severity
0% No conflict

Drag the fixation target — near is blurry, far is sharp

near far focal plane (optical ∞) Eyes LCD fixation conflict gap
What your eye sees
A
Vergence (where eyes aim)
Accommodation (optical infinity)
Conflict gap

Pupil Swim & Diplopia

Explore how IPD-IAD mismatch cause diplopia (seeing double) in a virtual reality system. Drag lenses left or right to shift them relative to the pupils. Use the sliders to adjust the eye relief and fixation distance.

What you see
Fused
8.00 m
15.0 mm
0% Fused
IPD60 mm
Lens ⌀50 mm
Eye relief15.0 mm
R offset+0.0 mm
L offset+0.0 mm
IAD60 mm
Vergence
FOV half
Err R0 mm
Err L0 mm

Drag lenses left/right · Drag fixation dot · Sliders set distance and eye relief

scene IPD 60mm eye relief IAD R L R lens L lens fixation
Right eye ray
Left eye ray
Separation (diplopia)

Pupil Swim: Dual-Eye Lens Model

A more detailed model showing left and right eye lenses independently. Move your mouse or finger over either lens to control gaze direction — the perceived scene panel shows how nasal vergence versus temporal vergence produce different distortion patterns. This reflects the actual optical geometry of aspherical and Fresnel HMD lenses under IPD mismatch.

0% Fused

Nasal gaze (inner) = eyes converge · Peripheral gaze (outer) = eyes move together

Left eye
offset
+0.0 mm
Perceived scene
Right eye
offset
+0.0 mm
On-axis — fused
Left eye image
Right eye image