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