iPhone Software Review: RulerPhone
Disclaimer: Software author Ben Kamens asked me if I'd like to review his application. He paid for the AppStore download plus a tip, so this is technically a sponsored review. But it's still my very own opinion 
This is a review of the iPhone application RulerPhone which can be downloaded in the AppStore for 2.39€ (or $2.99).
RulerPhone allows you to measure the size of things photographed with the iPhone's built in camera. You can either do a snapshot within the application itself or choose a photo from your library.
To calculate the sizes in the image RulerPhone needs a reference object. Ben decided for a common object everyone is carrying around today: a credit card. The dimensions of those plastic cards are well known and universal all over the world.
To measure an object you need to place your credit card directly in front of it and take a picture of it and the object having both facing you directly. As Ben says: “RulerPhone's accuracy depends on the user's ability to follow the on-screen instructions”. As soon as your objects are not ideally aligned, the accuracy will suffer.
I took a few measurements. One of them was photographing myself in a mirror holding the card. Not an ideal measurement, but RulerPhone calculated my height just 10 centimeters short probably correct because I wasn't standing straight. In an attempt to make a shot in the most ideal way, I taped my card to the center of my monitor and took a shot facing it directly. The calculation was only 1 centimeter off the real value.
The last measurement was closer to a real use case. I took the picture of my book shelf like you might do in a furniture shop. RulerPhone calculated it with 94×169 cm – my folding ruler says 94×174 cm. Close enough I'd say.
The software works as advertised. It is very stable, easy to use and comes with a very visual help. Measurements can be taken in metric and US units.
To be honest I probably wouldn't have bought RulerPhone my self because I probably rarely need it. But for people who are bad at estimating sizes and often have the need for it I can recommend it. There is also a free “light” version for smaller measurements.
