Spearfishing · Aotearoa New Zealand
SpearSight measures a fish underwater, from your iPhone, while it is still swimming - and tells you how far to trust the number it gives you.
± 8 mm (95%) · 1.4 m · 6 valid views
How it sees
Your iPhone does not have a camera. It has a set of them, sitting a little apart, each looking at the same fish from a slightly different place. SpearSight runs them together and works the length out of what they disagree about - no tape, no float, no second diver, and nothing to place by hand while you are holding a gun.
The lenses are used as a set rather than one at a time. Each pairing is strongest at a different distance, so the app takes whichever one has the better claim and shows you that. There is nothing to choose or configure.
On-device AI picks out every fish in view and follows each one as it moves, frame after frame, while you are still lining up. It runs entirely on the phone - nothing is uploaded, and it works with no signal at all, which is the only behaviour worth having underwater.
Water bends light, and so does the flat port on a housing - everything looks closer and bigger than it is. SpearSight corrects for that, and for the water you are actually diving in rather than water in general.
On the screen
Every row of the readout is always in the same place, whether or not there is a fish in front of it. Nothing appears and disappears while you are trying to read one number off it.
What it will and will not claim
A length with no idea of its own error cannot settle a legal-size question, and a plausible number is impossible to tell from a good one. So every reading carries what it is entitled to claim, and the app would rather show you nothing than something it cannot stand behind.
Properly measured, with a real interval around it. Only these are allowed into your dive log.
Something about the shot does not support calling it a measurement - a fish running off the edge of frame, for instance. Shown to you, never recorded.
Not enough to work with. Reported as the absence it is, with the reason, rather than filled in with a guess.
Your water, your rules
You set the minimum you are fishing to - the species, the length, and where the figure came from - and SpearSight compares against that, telling you when a fish is over, under, or genuinely too close to call. Size rules change by region and by season, and a stale number printed in an app would be read as authoritative by somebody standing in the water making exactly the decision it is wrong about.