General recommendations for viewing angles and distances for desktop workstations, control surfaces and video walls of control rooms.
First of all, it is necessary to note that horizontal and vertical viewing angles are different, because of physiological characteristics of body and head. Horizontal angles are generally wider and more symmetrical.
Also viewing angles are different for fixed head and movements. Major information and indications should be visible without head movement.
Comfortable viewing angle for fixed head to perceive information is 60º (±30 degrees from axis of symmetry).
Extra 30º sector is available around this area for peripheral non-critical indications.
Additional 20-30º peripheral sector for both left and right sides is observable by the operator without movement of head, but data in these locations are unreadable. These areas may attract (or may not) operator’s attention with blinking animations, or dramatical changes of background color (like switching display on or off).
Vertical vision is not symmetrical to horizon level. The comfortable viewing direction axis is lowered down by 20-30º below the horizon if the operator’s body is vertically oriented (standing or normal sitting in an armchair). But for simplicity, top and bottom vision fields are calculated from horizon level.
Top vertical vision field is limited by 50º because of eyebrows. Bottom vision field is slightly wider, it is limited by 70-80º from viewing direction axis.
But because comfortable viewing angle is lower than horizon, the vertical vision field is almost symmetrical.
If head vertical rotation is added (which is less comfortable, than in horizontal plane), extra 20-30º are available. But these areas are limited for usage, especially the lower one, because input devices are typically located there. So, only limited passive indications can be added to top area (like small head-up displays). The user will focus on them only with his own intentions.