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Video for your head

The limited availability of VGA head mounted displays at reasonable cost suggests NTSC as a possible alternative. Indeed, early versions of WearComp have used NTSC, and there is a long history of availability of NTSC displays. Most notably, camcorder viewfinders may often be salvaged from broken camcorders and built into eyeglasses. I commonly obtain these units for under $20, so this is clearly the lowest cost solution. Larger tubes (such as some that I still have from 15 to 20 years ago) often last for many years and provide good resolution. There is a common misconception that NTSC resolution is significantly less than VGA. This misconception arises from cheap game displays and consumer television both of which have poor resolution. However, good camera viewfinders can have as much as 1000 vertical lines of resolution, and can therefore adequately display VGA resolution images or text. Some experimentation is needed because text modes in VGA are often not 60Hz, but many camcorder viewfinders will sync at 60 or 72Hz (adjust the vertical hold trimpot or the like appropriately).

Steve Mann
Wed Dec 24 05:46:06 EST 1997