H4VR: One-handed Gesture-based Text Entry in Virtual Reality Using a Four-key Keyboard

What is it about?

H4VR is a one-handed gesture-based text entry method in Virtual Reality (VR). It uses a four-key soft keyboard based on the Huffman codes. In H4VR, base 4 Huffman encoding generates non-redundant codes for the English alphabet using the character frequency distribution of a corpus. The codes consist of four digits '1', '2', '3' and '4'. Note that more recurring characters such as 'E' and 'T' are assigned shorter codes, whereas less frequent characters such as 'Q' and 'Z' are given longer ones. This can minimize the gesture per character (GPC). H4VR uses two layouts of the same keyboard. The figure below shows the layouts and the gestures used on each layout. The flat layout is illustrated on the left, and the cross layout is on the right. Each layout uses a different set of hand gestures for key selection. In the flat keyboard, a method called code-based selection is used. An open hand is idle when the user is not selecting any key. Closing the index, middle, ring, and pinky finger at a time, selects the first, second, third and fourth key from the left, respectively. In the cross keyboard, the virtual mouse selection method is used. An open hand allows for moving the cursor and positioning it on a key. The key with the cursor on top is selected by closing the thumb.

Featured Image

Photo by Vinicius "amnx" Amano on Unsplash

Photo by Vinicius "amnx" Amano on Unsplash

Why is it important?

Firstly, using an ambiguous keyboard can mean presenting a smaller keyboard to the user since fewer keys are required for typing. This means less occlusion of the screen and fewer gestures needed for key selection, again due to having fewer keys. Secondly, gesture-based typing can eliminate the need for using VR controllers, which can lead to hand fatigue, is challenging to use for users with mobility issues and can reduce the sense of immersion. Finally, H4VR's one-handedness can make it more accessible for users with mobility conditions, leaving one hand free for other tasks.