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Buying a Touchscreen for Windows 8, Episode 2

As I dig further into the touch requirements for Windows 8, I’m learning more and more about touch technologies along the way. Alas, I’m also learning how very few of the currently available touchscreens meet Windows 8’s touch requirements for a minimum of 5 simultaneous touch points (to support all those cool touch gestures we’ve come to know and love from smartphones and the iPad).

Touch requirements are specified in these MS documents

Touch requirements are specified in these MS documents

I found the whole thing confusing and frustrating enough — a  sensation my Mom used to call “confrusticating” — that I turned to my colleagues at the Internet Press Guild for some help and guidance. HDTV expert Alfred Poor was kind enough to share a contact with me to somebody who specializes in touch technologies and has been designing and consulting in this area since the late 1980s when he got involved with an early and very popular ruggedized PC platform for military and emergency services use. I’m talking about Geoff Walker, of Walker Mobile at He’s a long-time expert and full-time consultant and writer on mobile computing with a particular emphasis on touch technologies. Check out his Website, where you’ll find a wealth of valuable and informative materials on touch technologies of all kinds. Geoff has also been a guest editor on Touch Technology for Information Display magazine since 2007 (where a search on his name produces over 500 hits), and has contributed numerous stories on touch to other industry publications as well.

In a lengthy email reply to my request for guidance on touch technologies in the Windows 8 framework, Geoff identified no fewer than 14 different touch technologies that are currently available in some commercial form or fashion in the form of touch displays. Fortunately, he also identified those three technologies that he indicated were “…highly likely to meet the [Windows 8 Touch Logo] spec[ification].” These are as follows (please note that this post was edited heavily on 2/9/2012, the day after its original posting to incorporate extensive feedback that Geoff very kindly provided to me):

1. Projected Capacitive (aka “pro-cap” or “P-cap”): This is the type of touchscreen that is used on the iPhone (a type that uses two electrodes with a two-layer sensor). It’s both sensitive and accurate, but also a fairly costly technology (though devices of over 100″ are now available using this technology, they are fabulously expensive and most emphatically NOT consumer- or even casual business-class devices). There are a fair number of pro-cap displays available that work with Windows 7 right now, but the vendors typically don’t document the number of touch points they support in their technical specifications (Geoff points out that this is not a good sign, and indicates many OEM vendor’s somewhat lackadaisical attitudes toward touch technologies).

This hasn’t really been an issue until Windows 8 requirements came out; before that multi-touch simply meant “two or more simultaneous touch points” to all parties. But in phone calls to vendors like Planar, ELO, Acer, HP, and others who make pro-cap touchscreen displays, I’m learning that most of them currently support only two or three simultaneous touch points, somewhat short of the 5 that the Windows 8 Touch Logo requirements mandate (see pp. 25-35 of the “Windows 8 Device Requirements” download PDF). Still other makers, most notably Perceptive Pixel and 3M, do support 10 or more touch points already, and provide ample touch specification details for those devices, but they are much more expensive than run-of-the-mill touch screens. Most vendors have pro-cap systems under development to meet the Window 8 Touch Logo requirements and should have systems ready to meet those requirement by the time the OS goes into general availability (probably in October 2012, according to any number of rumors from usually informed sources). Pro-cap is likely to be quite important for tablets and convertible notebook PCs with touchscreens, because it is the most widely used technology for touch in portable and mobile devices; it is a mainstream technology for displays from 2-17″ in size (but again, primarily for devices that use only touch, or can convert to exclusive touch use; source: Geoff Walker).

2. Camera-based Optical(aka “optical touch”) uses two or more CMOS infrared cameras placed atop a display, pointed across the display surface. These detect and position the presence of a touch on the screen using mathematical triangulation techniques and backlighting to create shadows when a finger or stylus  makes a touch at some particular on-screen location. Perforce the use of cameras makes this type of touch technology somewhat bulkier than those like pro-cap that rely the display itself to sense touch. Most such systems in use today have two to four cameras to support two or more touch points (though more than two is a challenge for today’s prevailing implementations, according to Geoff, though a new generation of six-camera systems is presently in development, with more touch points to match). Ongoing development should enable this technology to meet Windows 8 Touch Logo requirements when the OS becomes generally available late this year. Today, optical touch represents the most mainstream technology for stationary touch displays from 17-30″ in size (source: Geoff Walker). The very large SMART 800-series whiteboards use four integrated cameras to capture and analyze their user’s writing and drawing, for example, for a large-format application of camera-based optical.

3. Vision-based optical (like the Microsoft Surface product introduced in 2007) which uses infrared detection of diffused surface illumination on a touch panel through a camera that captures an image of the entire screen in use, then subjects what it “sees” to various forms of image and gesture analysis to determine what kinds of touches are occurring. Early versions of this technology require a camera with a vantage point of the entire screen, and will usually be mounted below or above the display to capture that data (and explains what makes it different from camera-based touch, which uses cameras mounted around the edges of the display itself). Modern versions use in-cell optical sensors (up to 2 million of them, says Geoff, in some implementations) instead of a camera, or multiple wide-view cameras integrated into display backlights. This technology is expensive and is primarily used on large displays of 30″ or bigger . Today, vision-based touch is an emerging technology, rather than a mainstream one, and is not likely to impact typical end-user desktops or mobile devices even for Windows 8 (except for conference room or very large-format displays). SMART’s touch tables use vision-based touch, and Geoff says “SMART has probably sold more vision-based touch than any other company in the world because of this application.” 

Interestingly, the vendors I contacted about their touch displays — for both camera-based and pro-cap touch technologies — indicated that their current Windows 7 touch displays work with the developer preview version of Windows 8, at least to some extent. They also indicated that so far, the gestures that the OS itself supports don’t require more than two touch points, and that no applications that require more have yet appeared. Geoff comments on this observation as follows:

Yes and no.  (1) Win7 limits its built-in gestures to two points, but Win7 also includes a well-developed gesture-processing library that an application can call to decipher gestures using any number of touches up to about 50 or so.  The limitation is that these gestures can only be used within a custom application – you can’t apply them on the desktop or to off-the-shelf Win7 commercial applications.  (2) There ARE applications already available that use more than two points.  The two best-known categories are 3D CAD applications, which use three or four points to control movement in three planes, and two-player games such as air hockey that use two points for each player.  If a touchscreen supports it, the “air hockey” game that’s included in the Win7 TouchPack can be played with four touch points.  That’s something you should try once you get a good 10+ touch pro-cap monitor.  You’ll find that the game itself is too slow and laggy to be that much fun, but it DOES work on Win7 with four touch points.

Obviously, I have to believe this is going to change with the upcoming “customer preview” (aka “customer beta”) release schedule for later this month (February 2012). It will be interesting to see if the OS itself will introduce gestures that involve three or more touch points at that time, and even more interesting to see how developers make use of more complex multi-touch gestures in their tools and applications. But for now, this represents uncharted territory where guesses and suppositions are the only forms of data available about how multi-touch will play out in the Windows 8 environment.

So where does this leave developers who want to create a multi-touch experience, or early adopters who want to realize such an experience? For the time being, it looks like some will choose to purchase — and settle for — devices with two touch points to get started on development, testing, and pilot studies, understanding that a new generation of 5-point touch devices will soon become available, necessitating purchase of more hardware sometime soon in the future. And, some will decide to shoulder the costs, and pay bigger bucks to get more capable touchscreens right away. Sigh: kind of a Hobson’s choice, but that’s life on the bleeding edge of technology!

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