Technical element related to HMD (n = 27).
| Sub category (No. of Articles) | Theme | Articles |
|---|---|---|
| Usability improvement (7) | Design | \#53, \#68, \#84, \#114 |
| Sensor | \#25 | |
| Input type | \#36, \#82 | |
| Software improvement (11) | Distance perception | \#14, \#56, \#81, \#94, |
| Motion perception | \#64 | |
| Color perception | \#102 | |
| Character recognition | \#20 | |
| LED control | \#113 | |
| Graphics enhancement | \#19, \#29, \#72 | |
| Hardware improvement (9) | Optical system | \#7, \#10, \#26, \#34, \#50, \#87 |
| LCD viewing angle | \#111 | |
| Holography | \#6 | |
| Other (literature research) | \#66 |