If I am to understand this thread discussion correctly, does it mean there is no public algo for multi-point touch sensing yet??<br>With so much of work done on projects like MS Surface, iPhone, the Jeff Han stuff.. and recently HTC Diamond, I took it for granted that it must already be there among the large resource pool of opensource developers.<br>
<br>Rahul J<br><br><br><div class="gmail_quote">On Fri, May 30, 2008 at 2:46 PM, Ben Lau <<a href="mailto:benlau@embedded.hk">benlau@embedded.hk</a>> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div><div></div><div class="Wj3C7c">On Thu, May 29, 2008 at 7:11 PM, Joerg Reisenweber <<a href="mailto:joerg@openmoko.org">joerg@openmoko.org</a>> wrote:<br>
> Am Do 29. Mai 2008 schrieb <a href="mailto:boris.stender@gmx.de">boris.stender@gmx.de</a>:<br>
>> Hi Joerg,<br>
>> as it seems that my mail did not reach the community list (I am not a<br>
> subscriber, just monitoring the archives) may I ask you directly the question<br>
> regarding "multi tutch" :-) . See below:<br>
>><br>
>><br>
>> Hi all,<br>
>> if the geometric average point is returned if multiple points are touched<br>
> wouldn't it be possible to have a fake multi touch, e.g., by doing the<br>
> following:<br>
>><br>
>> Press point A<br>
>> -> Vector A is returned<br>
>> Additionally press desired point B<br>
>> -> X = (A+B)/2 is returned<br>
>> -> calculate B = 2*X-A<br>
>><br>
>> Questions:<br>
>> Would this be managable?<br>
>> What time difference would be required between first and second (and<br>
> third ...) touch, to recognize such a multi-touch action and reliable<br>
> distinguish it from a single touch at position X?<br>
>><br>
>> And one more comment: If that would work you could also detect multi-touch<br>
> gestures (even if limited), e.g., use the first point statically (maybe a<br>
> focus centre) and handle the second point dynamically (maybe for zooming in<br>
> and out).<br>
>><br>
>><br>
>> Boris<br>
><br>
><br>
> there are two resistors in the touchpad, one for X and one for Y. We only see<br>
> them changing on a touch, thus giving us the coords. A concurrent second<br>
> touch just changes the R values even more, but we get no info about whether<br>
> we touched a second point or we moved the finger. So what you suggest is a<br>
> gesture recognition. Things become nasty because even the "geometric middle"<br>
> isn't true but depends on pressure of one to pressure of other touchpoint<br>
> etc.<br>
> You really get too few info out of the device to do anything reasonable with<br>
> it beyond singletouch (at least that's the way it is now. I plan to see<br>
> whether we can exploit dynamic pulse response of this design to get some<br>
> additional info. Same way you're testing cat5-cable for breaks. Don't hold<br>
> your breath though, chances are bad. And it's not on top of my todo-list)<br>
><br>
> cheers<br>
> jOERG<br>
><br>
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><br>
<br>
</div>Two-finger input with a standard touch screen<br>
<a href="http://portal.acm.org/citation.cfm?id=1294239" target="_blank">http://portal.acm.org/citation.cfm?id=1294239</a><br>
<br>
This paper introduces a method to detect two fingers using a<br>
"standard" touch screen. I haven't ready it deeply so I can not say is<br>
it applicable on OpenMoko platform , but I think it is worth to study.<br>
<div><div></div><div class="Wj3C7c"><br>
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