Specifications

Learning Spaces Guidelines
AV & Teaching Station: 24
The dimensions of the projected image in learning spaces should be
proportional to the viewing distance. The specification given by the
AETM guidelines is that the furthest viewing position should be no
more than 5.3 times the height of the display and this forms good
general guidance across a range contexts.
In reality the maximum acceptable viewing distance (or conversely
the minimum image size) is dependent on the type of material being
shown. Giving a demonstration of how to use a software application
such as Excel will require students to be able to see much smaller
objects and finer detail.
One alternative method for calculating the minimum dimensions for a
display within a teaching space is based upon this logic – the ‘4:6:8
rule’. According to this rule the minimum image height should equal
the maximum viewing distance divided by a factor of:
4 for Excel documents or items for inspection
6 for PowerPoint, graphs or typical presentation material
8 for video viewing
For the sake of simplicity it should be assumed that any display
being installed in a teaching computer cluster room will be used
for detailed viewing and therefore priority should be given to either
increasing the display size or reducing viewing distances by the use
of multiple or repeater screens.
The type of projector, standard throw v.s. ultra short throw, should
be dictated by the display requirements (i.e. minimum dimensions
proportional to the maximum viewing distance as per the 5.3 rule
above) and the installation/mounting conditons in the location (e.g.
avoid UST if a stud wall is not sufficently sturdy).
In terms of the position of the projection surface most other
guidelines specify that the base of the displayed image should be
1200mm from the floor. Whilst this undisputed for standard throw
projectors this height should be reduced to 1000mm from the floor
when an ultra-short throw projector is being specified. The rationale
for the different floor to screen heights is that ultra-short throw
projectors may be retrospectively fitted with interactive capabilities
and a board mounted at 1200mm from floor is typically too high for
use as a interactive writing surface.
Calculations should also be made to ensure that the viewing angles
for those nearest the screen. 35º to the screen top or 15º to the
screen centre are the maximum viewing angles recommended in
order to avoid neck strain for viewers.
TASK
Projection
specifications
3.10
Reference
Association of Educational
Technology Managers
(Australia) “AETM Design
Guidelines for Tertiary
Teaching Spaces: 2nd
Edition”
http://www.aetm.
org/uploads/media/
AETM_ Audio_Visual_
Design_Guidelines_2nd_
Edition.PDF