The AlpineInker : Hardware, Accelerometers

Some Thoughts on Automatic Screen Rotation

Ken Hinckley — Thu, 08 May 2008 08:41:00 GMT

Automatic screen rotation has been popularized by the iPhone but is also available on the OQO Model 02 thanks to Kenrick's Automatic Screen Rotator Utility (executable download). Just hold the device the way you want to use it. The screen flips to the correct portrait or landscape orientation in one second. You don't even have to think about it. What could be simpler? Kudos to Kenrick for putting this great utility together and making it available for free!

This is a program near and dear to my heart. I cobbled together custom sensor hardware, including an accelerometer to support automatic screen rotation, for my old Cassiopeia E105 Pocket PC back in the late 1990's:

Here's our video of the Sensing Pocket PC, with screen rotation and other fun stuff too.

Video: Sensing Techniques for Mobile Interaction

Later, I built sensors for the original slate Tablet PC prototypes that were floating around Microsoft. Many devices now include accelerometers for drop detection, but I'm pretty sure my prototype was the world's first Tablet PC with an accelerometer. It came with an extensive user manual: TILT ME.

That wad of electronics on the top is my sensor module. Here, I'm using the Tilt-a-Sketch application. You could draw on the tablet like an Etch-a-sketch by tilting it back and forth. Yes, it was really hard to sign your name this way, and yes, if you flipped it upside down and shook it, it erased the screen. Accelerometers can be a lot of fun.

But what was the most useful? Like Kenrick's utility, it supported automatic portrait/landscape switching depending on how you held the device. After all that hard work I had to put into building my own sensors, firmware, and software, it's mind-blowing to see this available in a free utility that I can download from the 'net for an off-the-shelf device!

My demo had a few tweaks, some never published before, that might be useful future embellishments to Kenrick's Automatic Screen Rotation utility. In essence these tweaks reduce accidental changes to the display orientation when you're working with your device. They also help to avoid rotation of the screen when you go to set your device down on your desk. Plus there's one bonus idea I tinkered with, described at the end - let me know if you like it or not.

Dead Bands for Increased Stability

Dead bands between the screen orientations made the device tend to stick to the current display orientation. This helped to avoid accidental changes to orientation.

Plot of tilt angles versus inferred instantaneous screen orientation.

To change display orientation, the tilt angles had to pass all the way through the gray ±5° dead bands, and stay within the same display region for 0.5 seconds. No screen rotation occured in the central "Flat" area.

Rotation Preview

Feedback for impending display rotations makes automatic changes to the display orientation more predictable and controllable. My Tablet PC demo displayed a "THIS SIDE UP" arrow at the center of the screen as soon as the tablet was tilted in a different direction. The change to the display format occurred one second after the arrow appeared, but only if the device was still tilted towards the new display orientation. This allowed the user to stop tilting the device to prevent an inadvertent switch.

To foreshadow a change to the display orientation, an arrow appeared immediately when the user rotated the tablet.

Of course, the arrow should not be there all the time. The arrow vanished when:

The screen changed orientation. The arrow remained visible for a couple of seconds after the switch to provide continuing feedback.
The instantaneous screen orientation returned to the current display orientation for a couple of seconds. This case occured if a user acted on the feedback to avoid an accidental change.
The user set the Tablet down flat without changing screen orientation.

I used black color-key transparency (in a layered window) for the actual bitmap used in the code.

Motion Detection

Movement of the device serves as a secondary indicator of when to switch the display format. To avoid accidental changes to the screen orientation, my Tablet PC implementation waited for motion to stop before rotating the screen. For example, this made the device less likely to change screen orientations as you set it flat on a desk.

The OQO Model 02 supports only about a 4 Hz sampling frequency on the accelerometer, so it might not be feasible to implement good motion detection at present. Nonetheless it seems worthwhile to mention it, in the hope that an increased sampling rate becomes possible in the future.

One hack to detect motion is to calculate how much the tilt values are changing, as follows:

Δx = tiltX - prevTiltX

Δy = tiltY - prevTiltY

sampleEnergy = √(Δx² + Δy²)

signalEnergy = signalEnergy*(1-α) + sampleEnergy

In the final equation, α is a decay rate. I used 0.25, with the tilt values in degrees, and signalEnergy initialized to 1.0. Motion "begins" when the signal energy rises above an onset threshold for a few samples and "stops" when the signal energy drops below a termination threshold.

Movement helped to control switching of the display format as follows:

When movement stopped, if the physical screen orientation did not match the inferred instantaneous screen orientation, a 1 second time-out began, after which the software switched the physical display orientation.
If movement began again during this time-out, the time-out for the physical display switch was cancelled.
If the instantaneous screen orientation changed again during this time-out, the time-out was restarted at its full one-second duration.

Orientation-specific Tasks

Here's one other nutty idea I experiemented with. Maybe it's useful, maybe it's not.

I assigned specific applications to specific orientations of the screen. For example, here's a screen shot where I set up Excel to appear in the landscape format, and Windows Journal in the portrait format. Flipping my Tablet PC between the two would switch between the applications, rather than just rotating the screen.

Switching orienations can switch between sets of applications as well...

This offered a simple way to partition applications into task-specific sets for each screen orientation. Unfortunately my prototype of this feature never really worked all that well. You could check off windows as belonging to each screen orientation. The prototype would hide and show the windows as you rotated your tablet. But it had some bugs. Sometimes it would hide the windows permanently, never to be seen again. That's not terribly useful. So I never did usability testing on it, but I found something about it intuitively appealing. What do you think? Would you want this feature on your tablet or mobile devices?

Summary

My experience is that the devil is in the details with sensing techniques. Small touches here and there go a long way to keep the interaction invisible in the background, rather than becoming a focus of attention when things happen that the user didn't intend. Ultimately, the goal should be to create the best possible user interface. What is the best possible interface, you might ask?

The best possible user interface is the one that you don't even notice is there at all.

Resources:

Kenrick's blog: Teaching, Technology, and Learning
Kenricks' Automatic Screen Rotator Utility, download for the OQO Model 02
Ken Hinckley's UIST 2000 conference paper and follow-up journal article on sensing techniques.
Video of the Sensing Pocket PC

Research Frontiers: New Stuff Coming in Pen & Multi-Touch Interfaces

Ken Hinckley — Sat, 05 Jan 2008 09:53:00 GMT

The annual Computer-Human Interaction (CHI) conference is fast approaching (April 5) and the advance program has been published. That means AlpineInker can scan the list of accepted papers and see what looks cool - but the actual papers aren't available yet, so it's a fun guessing game to read between the lines and try to figure out what the research community has been up to.

CHI is considered by many to be the flagship conference of the broad discipline of human-computer interaction, so it's important to be aware of what developments are coming. The papers are all rigorously reviewed and it's difficult to publish stuff there - typically only about 20% of the submitted papers get accepted in any given year.

I also learned last week that I'll be the technical program chair for the CHI 2009 conference. That means I just got dramatically busier (as if 11 month old twins weren't keeping me busy enough) and I probably will be posting to this blog a little less frequently than I originally planned to.

Anyway, here are my picks for what look to be some cool devices and techniques that we'll all hope to see become more commonly available as soon as possible.

Navigation Techniques for Dual-Display E-Book Readers

Authors: Nicholas Chen, Francois Guimbretiere, Morgan Dixon, Maneesh Agrawala (University of California, Berkeley - University of Maryland, College Park. Full disclosure: Francois, Nicholas, Morgan and I have co-authored papers together; Maneesh is a former Microsoft Researcher who has also co-authored papers on pen stuff with me.

Imagine the Amazon Kindle meets the Nintendo DS - only much cooler. This is a project that Francois' lab has had going for a while, and from earlier demos they've done, I know it's a device with a pair of displays that are joined together by a hinge. So you can read stuff just like you would with a real book that has two pages facing one another. But you can also flip the two displays back-to-back so you have a two-sided UMPC type of device, or you can even separate the two screens at the hinge so you have two independent devices that you can use like separate sheets of paper, with different documents on them, and they stay synchronized using a BlueTooth connection. They've hacked up each of the displays with a motion sensor that lets you flip through pages much like you would leaf through the pages of a paper document. I would love to have a dual-screen UMPC like this that I could ink on - it would be the ultimate digital moleskine notebook. It will be very interesting to see what new developments they have come up with for this paper.

Update: Their web server has been having problems, but since the original post, I've been able to access their site briefly. They have a page about the dual-display ebook reader project and a video (WMV) showing how the motion sensing works.

I also found a few images. Here is what their original prototype looked like in the dual display configuration:

And here it is with the pages pulled apart:

Finally, here is a tantalizing shot that apparently shows the new version of their reader. It looks like they have gotten it dramatically thinner and lighter. I'm also excited to see the pencil next to it and what look to be small writing styluses (or is that styli?) attached to the bottom of each screen - maybe that implies we will be able to do inking on this thing some day!

In fact, they say that they prototyped this using a 3D printer to make parts of the case and a carbon-fiber composite bezel to really keep the weight down. It's amazing what a few clever university students can pull together these days.

Update #2: This seems to be an extremely timely bit of research given the announcement today of the e-detail Dual Display Tablet PC:

The e-detail product suggests another great scenario for the University of Maryland dual-display e-Book: set it up like a picture frame so one display faces each person in a face-to-face meeting. That would be fantastic for a highly strategic one-on-one meeting, such as playing "battleship" .

K-Sketch: A "Kinetic" Sketch Pad for Novice Animators

Authors: Richard Davis, University of California, Berkeley; James Landay, University of Washington, Intel Research Seattle. Full disclosure: I've co-authored with James Landay in the past.

Wouldn't it be cool to be able to set your ink and sketches on your tablet PC in motion? In theory it's possible to do this using ink with PowerPoint's animation features, but in practice it can really difficult to throw something together quickly. Well K-Sketch has some nifty ideas and techniques embodied in a fairly clean and easy-to-use sketching interface that makes it possible to do this super fast -three times faster than you can do similar things in PowerPoint. Now that sounds like fun.

This is one that you can soon play with yourself, according to k-sketch.org:

1/3/2008: We are very close to finishing our initial release of K-Sketch, and we expect it to be ready within a month.

K-Sketch will allow ordinary computer users to create informal animations from sketches. [...] Our design allows the most important types of motion to be defined with pen gestures, and gives visual feedback for coordination of events.

A video of of K-Sketch (WMV format) shows some of what it can do. The presentation is tailored for the academic audience, but the capabilities are very cool. Be sure to keep watching until the ski jumper double flip animation - try to imagine how tough it would be to do that in PowerPoint!

Indirect Mappings of Multi-Touch Input Using One and Two Hands

Tomer Moscovich, University of Toronto , Brown University; John Hughes, Brown University.

I don't have any inside scoop on exactly what this paper is about, but Tomer has done some very cool multi-touch interaction techniques in the past. He's also the person who came up with the "virtual scroll ring" technique that is the basis of the circle-the-pen-to-scroll gesture that has been a big hit with the tool ring in InkSeine. So I'm very keen to see what clever new things Tomer has devised in the multi-touch space.

Multi-Flick: An Evaluation of Flick-Based Scrolling Techniques for Pen Interfaces

Dzimity Aliakseyeu, Philips Research Eindhoven, Netherlands; Pourang Irani, University of Manitoba, Canada; Andres Lucero, Eindhoven University of Technology, Netherlands; Sriram Subramanian, University of Bristol, U.K

Scrolling with a pen, virtual scroll ring notwithstanding, is something that begs for cool gestures that let you easily express different granularities and speeds of how to flip through your documents. From the title I'm inferring that these researchers have come up with a few different kinds of flicking gestures that let you navigate through stuff quickly and easily. They don't have the paper posted on their web site yet, but it looks like they are implementing it using a pen on a tabletop computer (kind of like the Microsoft Surface). They have about a half-dozen other papers - one with a video - of other interesting work they've done on tabletop devices.

"It's on my other computer": Computing with Multiple Devices

David Dearman, University of Toronto; Jeff Pierce, IBM. Full disclosure: Jeff Pierce and I have published together before, and are both former students of Randy Pausch, who is waging a now-famous losing battle with pancreatic cancer. But he's hanging in there so far and still making great contributions to society.

All of you mobile enthusiasts out there have struggled with keeping your mobile devices and computers in sync, only to have some key bit of information elude you at exactly the moment you need it. Jeff Pierce had some cool projects going when he was a professor at Georgia Tech on "Personal Information Environments" where his vision was that you could walk around with your cell phone or notebook computer and use opportunistic annexing to dynamically associate your device with displays, touch-screens, keyboards, or other devices you encountered. My inference is that he's made some nice progress in this space and has come up with some techniques to maintain easy access to all your stuff across multiple devices.

PieCursor: Merging Pointing and Command Selection for Rapid In-Place Tool Switching

George Fitzmaurice, Justin Matejka, Azam Khan, Mike Glueck, Gordon Kurtenbach, Autodesk

This is the same crew of guys who came up with all the interesting user interface stuff in the Alias Sketchbook application, which I still use to this day for sketching on my Tablet PC. It looks like they've come up with a spiffy way to switch between different tools with your pen on your Tablet PC without having to move the pen to the edge of the screen and tap on some silly icon or bring up a menu. There's an intriguing thumbnail image of the technique on Azam's web site:

Thumbnail of PieCursor from Azam's web site - can you guess how it works?

My best guess is that it is some kind of a floating menu that follows your pen. Then you can activate a radial menu on it to pick tools (like a Zoom function), but you can continue the same stroke to specify how much to zoom. This is a trick known as "merging" in some other papers, hence my guess based on the title of their paper. This could be something really cool to let you pick different tools and commands much faster on your Tablet PC.

Those are the highlights from my short list of what caught my eye, but there's well over 100 papers to appear at the CHI conference and I'm sure there's many other gems in there. For example, there will be a whole session on image search interfaces, including CueFlik from Microsoft Research. I'm not involved in that work but I've seen that demo in the labs here and it's pretty cool. Image Search is one area where I think Microsoft Live Search has a clearly superior user interface to Google: for example, try a Live image search for Tablet PC. CueFlik is something that could make this even cooler and more useful.