Last Saturday was an interesting day. Mid afternoon my good friend Ben Dodson came over. He wanted some help (or some basic prodding in the right direction) to help make an app for his new iPhone 3GS. The app he wanted to make? A metal detector of course!
One of the things the new iPhone 3GS has is an internal geographic compass. This is achieved with a device known as a magnetometer – something which can give you a 3-dimensional X, Y, Z co-ordinate to the magnetic north pole. The great (and sometimes frustrating thing) about these devices is, that they’re influenced by nearby metallic object, albeit, not by much. Still, this ‘negative’ effect is one we wanted to exploit, and turn into the first visual metal detector app for the new iPhone.
My ‘study’ is actually the largest bedroom in my house, consisting of a high end, 3 monitored PC, a sofa in-front of this, surround sound and a projector, which can display a 4th, 100″ screen from my PC (which I use for TV and DVD’s) or my Wii. Ben sat on the sofa with his Macbook, poking around with the iPhone developer SDK whilst I sat at my desk, seeing what physics were involved in making the app work. After some quick testing we discovered that this would be a fairly easy thing to achieve.
During tests I noticed that metals which tend to be more influenced by magnets were also the items most easily detected – Iron was found easily, but Aluminium barely registered. One of the other things I discovered was the influence of magnets on the 3GS – the stronger the magnetic flux, the higher the influence on the 3D geometrics. After this discovery, and our current lack of icon for the project I had an epiphany and said “Flux. This thing measures Magnetic flux too. How about a flux capacitor?”. Anyone who loves Back to the Future will know what that is! This remains my most significant contribution to the project.
Ben began to code the scale and graphics, whilst I created a mask to produce the curved effect, and generated 20 distinct square wave sounds, one for every 5 points of difference in our calculation of metalness / flux. Soon after finishing this whilst Ben was still coding, I began to work on the website. Ben had an idea in his mind of what the site could look like, which I largely kept to. You have to love the little South Park style versions of us (can you tell who is who?) It was decided that, due to IE6′s lack of position:fixed we’d instead have a little conditional message for IE6 users, informing them of some better browser choices.
After we’d finished producing the app and start of the site, we went to record the video in my dining room, with my Panasonic Lumix (The resolution on that thing isn’t too bad for a video). The final cut of this video features me swearing (sorry about that) and the sound of the doorbell, as a nice man delivers our Indian curry. Mmm.
Dinner over, Ben cut and uploaded our video and submitted our app, whilst I polished off the website. We also discovered at this point that it was gone midnight and Ben had missed the last train (bless). I very generously let him stay in my spare room.
Morning came, some more tweaking, and a special twitter feed for our new collaborative code site and that’s that.
So, go now and witness the fruits of our labour, achieved in one Saturday evening: philandben.com
Hello from Russia!
Can I quote a post in your blog with the link to you?
You sure can