Monday, June 2, 2008

See-through HMDs have lots of ground to cover

See-through HMDs (sometimes referred to as 'personal displays') are sometimes portrayed as combining eyeglasses with a video ipod. In a perfect world, they look like cool fashion accessories, are so light that you can wear them anytime, yet overlay what you see through them with computer-generated images. Perhaps it's a movie that you can watch on a plane. Perhaps it's driving directions or text messages from your friends.

However, to get there, many problems remain to be solved:
- Brightness: can these devices be used in a sunny day?
- Weight: can you really walk around with them all day?
- Power consumption: how long does the battery last and where is the battery placed? If the battery is part of the HMD, it adds weight. If it's on a belt-clip, it adds inconvenience and perhaps a cable.
- User interface: how can you control what information is displayed, or when it is shown.
- Dual use: if the goal is to watch a movie, it's often better to block out external imagery. But how? Do you add a cover to the front? Do you make the glass part so dark that it's effectively like sunglasses?
- Placement of information: if the information is placed in the central vision, it might intefere with reading tasks. If it's placed in the peripheral vision, it is difficult to read. If it's both, you need a very wide display element.
- Stereo vision? At some level, a monocular display (one eye) might be sufficient for textual information. However, if you're looking to augment a scene, the feeling of stereo may be very important. Stereo, however, nearly doubles the weight, cost, power consumption and cabling requirements of the display electronics.
- Sound - can you or should you integrate the display with an earpiece
- Cost, for obvious reasons

I'm curious to see what Apple (who recently published some patents on this) and Sony (recently showing a cool display at SID 2008) have up their sleeves for this product category.


S├ębastien "cb" Kuntz said...

And if you want to do some Augmented Reality, you will need a very precise tracker, also lightweight with very low consumption, and that is without talking about the processing power such a task would need.

Ah, vivement the future !

Larry said...

I saw the Sony display at SID and it was impressive---very good color characteristics due to their hard work on studying holographic optical elements and hard-core customization of the microdisplay drive electronics. The FOV was only 16 degrees horizontal though...very tiny. It was very slick and slim, almost that "cool fashion accessory" ran off a small, slim battery for over an hour. I don't think its a product you can buy yet but it caught a lot of eyes at SID 2008.
(Where I presented a paper on the Sensics tiled display and other things we are up to...)