Viewing Angle and Viewing Area
Viewing Angle
Describe the relationship of display screen characteristics with respect to the lateral location of the viewer.
Projection screens and displays have different characteristics regarding the acceptable angle at which they can be viewed.
You should create a seating plan for the audience, where all characters on the screen remain decipherable. Viewing angles must be such that geometric distortion or apparent deformation is tolerable. For example, a circle will appear less circular as the viewing angle is enlarged. As the "O" becomes elliptical, the ease with which it may be recognized diminishes, and beyond a certain point, characters risk becoming indecipherable. A viewer perpendicular to the first character in an 80 character line must be able to read the last character - the angle formed between the viewer's eye and the last character should not exceed 45 degrees for optimal viewing.
- To determine viewing angles, consider the least favored viewer as being no further off axis than 45 degrees from the furthest outside edges of the screen. Optimally, all viewers will be in an area no greater than 45 degrees off the far side of the screen or outside of the viewing area of acceptable brightness drop-off (50 percent). These criteria vary for each system.
Definitions for clarification:
- On-Axis: The best viewing is on axis to the image. As the viewer position moves off axis, the quality of the image will decrease, depending on the characteristics of the screen.
- Viewing Angle: The Viewing Angle refers to the polar displacement with respect to the display center line (axis) in which viewers will receive the best results when viewing a displayed image. A viewing angle of 90 degrees includes 45 degrees to each side of the axis. Locating viewers within this 90 degree angle will help ensure good image quality. This provides the basis for determining the layout of the audience.
Viewing Area
Describe the criteria for determining the optimal seating areas within a viewing room.The AV Designer specifies where the seats will be (and will not be) positioned to accommodate an audience's needs, ensuring that all audience members see a quality image.
In addition to the distance from the screen, we must also consider a viewer's angle from the screen. The positions on the edges of the viewing cone are not the best angles, and the persons sitting in those positions are referred to as the least favored viewers, or LFVs. The LFV can be thought to be sitting in the worst seat in the house. For example, in a boardroom it is the two seats at the front of the table.
Best Practice
- Screen Gain: High-gain projection screens can limit viewing angles, since these screens are more directional, focusing the projected light along the axis of the projector.
- Furthest Viewer: When designing the viewing area, remember that the maximum viewing distance is based on the amount of detail we need to see in the image, not the resolution of the image.
- Good and Acceptable: A room can usually be divided into good and acceptable viewing areas. The good viewing area is within 45 degrees of the projection axis, creating a 90 degree "viewing cone" oriented on the center axis of the screen. The acceptable viewing area is within 45 degrees of the edge of the image.
