VisualRuler Uses Your Camera to Measure Objects in the Real World
iOS: Sometimes you need to quickly measure something and you probably don’t carry a ruler with you, but of course there is an app for that. VisualRuler gives you a decent estimate of object dimensions using your phone’s camera.
Here’s how it works: To give the app a guideline for scaling, you include a credit card (or equivalent wallet-sized card) next to the object you are measuring and then take a photo. All credit cards are the same size, so this is a great way to indicate the scale you probably have in your pocket. (And no, the photo never leaves your phone, so they don’t spy on your card.)
Then you drag the measurement lines onto the card and onto the object you want to measure. This is not a very accurate solution, but it will give you a decent estimate. Keep in mind that it does not account for perspective distortion, so it is only intended to measure objects on a flat surface. But it works pretty well – the keyboard I measured is exactly 11.2 inches long; the app rated 10.93 inches.
Since a wallet-sized map is used as a reference, you can only measure fairly small objects, and the UI is a little confusing at first, but the developer will hopefully refine it. Its limited usefulness certainly makes the $ 3 price tag questionable, but I’ve had enough fun with the new product not to mind.