Re: touchscreen calibration again

On Tue, May 18, 2004 at 10:48:53AM +0200, Michael Opdenacker wrote:
> Hi Lau,
>
> Great work! I'm very please that you could achieve this level of accuracy!
>
> >2: End user calibration: An affine transformation is applied to the
> >output of the linearization. This transformation will compensate for
> >variation among individual IPaqs.
>
> I hope this can be handled by the standard user calibration tools. We
> will test this!
>
> >
> >A second order model is almost as good (3.7 and 2.2 pixels average
> >errors), and practical experiments are neeed to determine if 3rd order
> >is worth the extra CPU cycles:
>
> Right! We will have to see, for example with an on-screen drawing
> program. However, I don't think that 8 extra floating point
> multiplications will be too hard to handle...

Probably not, but you have to be aware that the Xscale doesn't have any
hardware floating point support: all floating point operations are
trapped and emulated by the kernel, which is quite some overhead.

But then again, you probably won't cause thousands of ts events per second,
so it might not matter that much. I guess you will just have to try and
see :)

cheers,

Joris

PS: thanks for the great job you've been doing!
Received on Tue May 18 09:08:34 2004