Re: correction : ts calibration

Pocket PC only asks for five points, so we should be able to calibrate with five too. Mayhe they fit a predefined lookup table to the five points.

Matt

-----Original Message-----
    From: "Andrew Zabolotny"<zap@homelink.ru>
    Sent: 4/17/04 2:09:15 AM
    To: "h2200-port@handhelds.org"<h2200-port@handhelds.org>
    Subject: Re: [H2200-port] correction : ts calibration
      On Fri, 16 Apr 2004 16:21:51 +0200
    Alain2210 <alain2210@free.fr> wrote:
    
> For better understanding the value given by the touchscreen. I have got the
> raw values when the pen follows the borders of the screen.
> It gives this :
> http://alain2210.free.fr/geombrut.pdf
    Pretty sad. Until now I have assumed all touchscreens have a linear response,
    but now I see that at least h22xx doesn't. I don't know yet how a general
    transform equation should look like, but it will have to be more complex than
    just multiplying an 1x2 vector by a 2x2 matrix.
    
    How the calibration process should look like? Does it make sense to
    display something like "Please follow with the pen the borders of the screen
    in the following order: top-left - top-right - bottom-right - bottom-left -
    top-left"? Maybe this calibration process will be even easier to accomplish
    than clicking four or five screen points. Perhaps a final step would be to
    click the central screen point in order to detect non-linearity within the
    touchscreen values area. Oh.
    
    --
    Greetings,
       Andrew
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Received on Sat Apr 17 13:57:24 2004