Screens and Sightlines

Screen based content forms a critical part of modern teaching and learning practices. The content displayed can vary wildly between courses and units but commonly includes the following:

• Slide Show Presentations using Microsoft PowerPoint, Apple Keynote and similar presentation platforms
• Video Content – generally hosted on online video platforms such as YouTube, Echo360, Microsoft Streams or on USB disks
• Websites
• Word processing documents, spreadsheets and other text-based applications
• Detailed graphs and analytical diagrams
• Engineering documents such as CAD drawings and Geographical surveys
• Fine Arts materials such as images of paintings, illustrations, drawings
• Data visualisation and scientific modelling
• Medical imagery
• Virtual and Augmented Reality
• Live camera imagery from point of view cameras, video conferencing, whiteboard and document cameras

Depending on the learning being delivered, the correct screen size, brightness, resolution and technology must be selected to ensure clear viewing, accurate colour rendition, reduce eye and neck strain and ensure dimensional accuracy.

Viewing Standards

DTS AV utilise two industry standard metrics for determining the correct sizing and contrast ratio for screens.

AVIXA Display Image Size for 2D Content in Audiovisual Systems (DISCAS) for screen sizing

And

ANSI/Infocomm 3M Projected Image System Contrast Ratio (PISCR) for contrast ratio

Both make reference to viewing categories in order to assist with selecting the right size design.

Viewing Categories

Most environments encountered within Curtin will match one of the following categories, which are defined in PISCR and are summarised as:

Type	Description
Passive Viewing	The viewer is able to recognise what the images are on screen
Basic Decision Making (BDM)	The viewer can make basic decisions based on the images on screen
Analytical Decision Making (ADM)	The viewer is fully engaged with minute detail present in the content on screen, and needs to resolve every element of the projected image
Full Motion Video (FMV)	The viewer is able to discern all detail provided by the cinematographer necessary to support the storyline and inferred meaning

Passive Viewing

The viewer is able to recognize what the images are on a screen and can separate the text or the main image from the background under typical lighting for the viewing environment. The content does not require assimilation and retention of detail but the general intent is understood There is passive engagement with images on a screen. Digital Signage and Meeting Rooms may fall into this category.

Basic Decision Making

The viewer can make basic decisions from the displayed image. The decisions are not dependent on critical details within the image, but there is assimilation and retention of information. The viewer is actively engaged with the content (e.g., information displays, presentations containing detailed images, classrooms, boardrooms, multi-purpose rooms, product illustrations).

The viewer should be able to understand what is being communicated. Graphic images and text are legible to the extent that the viewer can make basic decisions on the basis of what is being seen. Decisions made are based on comprehending the informational content itself and are not dependent on the resolution of every element of detail.

Basic decision-making viewing applications include the presentation of photographs, detailed graphic images, product illustrations and information displays such as airline departures, sports scores or stock quotes. In this scenario, the information obtained from the projected image informs a basic decision by a fully engaged viewer.

In a typical basic decision-making environment (e.g., classrooms, multi-purpose rooms, board rooms), there may be some degree of ambient light control, such as window shades and zoned task lighting.

The majority of spaces within Curtin University would fall within this category.

Analytical Decision Making

The viewer is fully engaged with minute detail present in the content and needs to be able to resolve every element of the projected image. Analytical decision-making environments support professional assessments, such as the examination of medical imaging, engineering or architectural drawings, electrical schematics, photographic image inspection, forensic evidence or failure analysis.

Analytical decision-making viewing environments typically have controlled ambient light – particularly on or by the screen – often with darkened or anti-reflective surfaces and highly focused task lighting.

The minimum system contrast ratio for analytical decision-making was determined to be 50:1. The task group observed that, in practice, although achievable, close attention to both the system design and environmental characteristics will be necessary to achieve the desired contrast.

These spaces are rare within Curtin, however there are specific use cases where the ADM requirements will need to be met.

Full Motion Video

In this category, movies or other full motion videos are projected in a controlled viewing environment with an audience that has a high level of engagement with the content. The viewer is able to discern key elements present in the full motion video, including detail provided by the cinematographer or videographer necessary to support the story line and intent (e.g., home theater, business screening room, broadcast post-production).

Specialist Spaces

Specialist spaces should always be designed to reflect the specific requirements of that specialism. Whilst specialist spaces may not be formally covered by the AVIXA categories, the principles remain informative.

Examples of specialist spaces include:

• Cinemas should be designed to SMPTE or other industry criteria
  • If also used for non-cinema screenings, a lecture theatre should have projection and lighting which is configurable to achieve AVIXA’s Full Motion Video requirements, as well as the required non-cinema functionality.
• Professional medical imaging analysis (compared to training spaces, eg. DICOMM)

Aspect Ratios

All general purpose displays should be of a 16:9 ratio. Projectors may be 16:10 native, but are to be set to crop at 16:9 and project onto a projection surface which is 16:9.

In certain circumstance screens of alternate aspect may be installed, however a means of accurately ingesting 16:9 content must be provided which does not result in cropping, pillar/letterboxing or distortion of the image geometry. This may involve some form of video processor to provide a background image to avoid black bars providing pillar/letterboxing.

Viewing Area

Curtin Standards do not define a compliant room; rather they define the compliant viewing area (VA) as being within closest and farthest viewer distances, and within horizontal viewing limits of screens within the space.

In reality fitting all users within the compliant viewing area is unlikely, but it should be the goal. Coverage that contains 90% of users within the VA is the guideline.

Curtin has prioritised student placement in the following ways

• Students should not exceed farthest viewing distance
• Students may be slightly closer than the closest viewing distance

Spaces may have multiple displays. Functionally these displays can be either discreate (separate sources may be routed to each display) or mirror (2 or more displays showing the same thing). Within a space there may be a mix of the two – ie a room may have 4 projectors, 2 at the front, 2 at the rear. The left screen at the front and the left at the rear always show the same image as each other, and the same can be said of the right screens. The left and right screens can show a different image.

When considering these environments:

• Where multiple discreate displays exist, the viewing area within the space is the union of each display type. 80% of users in the space must be within the VA.
• Where displays are duplicating each other, viewing areas are additive.

In the example above, the front and rear left displays add together to determine the “Left” VA, the front and rear right VA’s add together to create the “Right” VA. These two areas can be plotted over the top of each other, and where they overlap is the compliant viewing area. 80% of students must be within this area.

This example does ignore that some students may be facing forwards and some rearwards for the sake of making a clear illustration. Where students may be using huddle tables etc, these items also need to be taken into consideration from a viewing area perspective.

DTS AV will either provide the project with approved screen sizing or will sign off on screen sizing once room dimensions and test fits can be provided.

Furthest Viewing Distance

One of the most important factors to consider when sizing a presentation system is the farthest viewing (FV) distance. It is this parameter that ultimately sets the height of a display system, often one of the most difficult items to coordinate in a teaching space.

Horizontal Viewing Angle

This is all about considering geometric distortion of displayed information. Once the viewer is more than 60° off-axis this distortion is typically unacceptable.

Vertical Viewing Angle

Scientific research indicates that comfortable head movement only falls within ±30° of the horizontal. The maximum vertical viewing angle is then 30° above the eyeline of the closest viewer.

Analytical Decision Making (ADM) spaces do not mandate the closest viewer, however the rules of geometric distortion and viewer comfort still apply. In an ADM space, viewers are expected to self-select their viewing position to afford themselves an appropriate view.

At Curtin, we use a standard eyeline of 1200mm AFFL for seated and 1700mm AFFL for standing viewers.