Seeing the world with labels

Wednesday, May 26, 2004

The auto-focus mechanism in a modern camera (digital or film) uses a matrix sensor to examine the sharpness of the image coming out of the lens. Focus is adjusted to get the sharpest image possible.

Now, since the lens knows what focal length is required to get an object into focus, it presumably also knows the approximate distance to the object.

Take a device armed with this knowledge, throw in a GPS unit, digital compass and two dual-axis accelerometers (to measure tilt), and you have a device that knows the location of whatever you are looking at. Add a digital map, point your device at a nearby building, and it’ll tell you the name of the building and who occupies it. Imagine how useful such a device would be to a tourist, city surveyor or, (replacing GPS with a small-scale triangulation system,) museum visitor.

In other news, I went into Kishore’s room to verify technical details before posting here and he pointed at the circuit board he was soldering. On it were two dual-axis accelerometers mounted perpendicular to each other. That board is going to perform auto-pilot duties on his Unmanned Aerial Vehicle, which already has a video transmitter and GPS unit. Imagine video tagged with location information.

basrya — May 26, 2004 10:32:14 AM — # ↩

Sounds like one helluva device.
any plans to file for patents? :)
vinodkumarvc — May 26, 2004 10:45:58 AM — # ↩

though i dont know wht a dual-axis accelerometer is .. other details sound pretty cool!!
- Kiran Jonnalagadda — May 26, 2004 11:08:33 AM — # ↩
  
  An accelerometer is a MEMS device measuring about 5mm squared by 2mm that can tell you what angle it is being held at, relative to gravity. It's sort of like an electronic spirit level. A dual-axis accelerometer is like two spirit levels positioned perpendicular to each other. By using one dual-axis and one single-access accelerometer, or using two dual-axis accelerometers and ignoring one redundant axis, you can measure your angle relative to the X, Y and Z planes.
  
  Of course, since gravity provides only one plane (horizontal), you can only measure movement along the other two planes (since acceleration behaves like gravity). But by comparing movement against a compass you can get the other two.
  
  Some digital cameras use an accelerometer to guess if you are taking a landscape or portrait shot and rotate the image appropriately. My Kodak CX4230 does that.
  - vinodkumarvc — May 26, 2004 11:16:05 AM — # ↩
    
    yo .. my Canon Powershot A75 also does that.
  - sriramb — May 26, 2004 3:18:04 PM — # ↩
    
    Accelerometer 101
    Accelerometers are typiclly made of mercury switches. Imagine a drop of mercury that moves in a cylinder. The inside surface of the cylinder acts like a variable resistor. So, if you have two mercury switches perpendicular, you can have an electrical circuit that measures the varying resistance produced in the cylinders. Cameras have similar MEM sensors. In fact, in some of the Canon SLRs, you can hear the mercury pellet make a sound when you tilt the camera.
killapop — May 26, 2004 10:48:21 AM — # ↩

Imagine how useful such a device would be to a tourist, city surveyor or, (replacing GPS with a small-scale triangulation system,) museum visitor.
add "enemy country", "george bush type maniacal village idiot".

That board is going to perform auto-pilot duties on his Unmanned Aerial Vehicle,point your device at a nearby building,
How bin would've loved that one.

good dope!

>hic
aivalli — May 26, 2004 12:23:53 PM — # ↩

*bows* to the creator !

-nerdy :)
mayuresh — May 26, 2004 1:59:34 PM — # ↩

That guy Kishore sure is cool, please give him my regards...
- Kiran Jonnalagadda — May 27, 2004 9:59:33 AM — # ↩
  
  Proud to be that guy's older brother. And humbled.
  - mayuresh — May 27, 2004 11:58:14 AM — # ↩
    
    Don't worry, you are cool too :)
moccacino — May 27, 2004 8:19:59 AM — # ↩

Say, do you know one Frank Jennings? Ex-employee, Chip.

...matrix sensor to examine the sharpness of the image...
As far as i know, you can still adjust hue, contrast, color saturation etc in Photoshop to get a sharper image. Of course the resolution can not be improved but the tool adopts the best color levels.
- Kiran Jonnalagadda — May 27, 2004 8:36:34 AM — # ↩
  
  > Say, do you know one Frank Jennings? Ex-employee, Chip.
  
  Yes, but we're not in touch.
  - moccacino — May 27, 2004 8:50:26 AM — # ↩
    
    i know. He is my colleague.
    - quizling — May 27, 2004 9:22:29 AM — # ↩
      
      The silent chap? Say hi to him from me... dunno if he'll remember me though!
      - moccacino — May 27, 2004 9:37:02 AM — # ↩
        
        He remembers you as the copy editor and says a Hi, back. :)
        
        Kiran Jonnalagadda — May 27, 2004 10:00:47 AM — # ↩
        
        If you guys have time to spare, here's something to amuse you for a while.