Classroom Display Sizes Just how big do they need to be? Timothy A. Dunbar, CTS Director of Computers and Instructional Technology Northcentral Technical College

Northcentral Technical College Main campus in Wausau WI, with 6 regional campuses and several Centers of Excellence spread out over 10 counties 118 Smart classrooms 55 IVC classrooms Dozens of smaller conference rooms Predominately using TVs, but some spaces have projectors - moving towards lampless projectors

The math behind the decision… We will go over two different ways to determine the proper display size Older non-standard “standard” Newer ANSI standard

4-6-8 rule Examples of the images requiring each ratio 8 - General: movies, talking head 6 - Detailed: PowerPoint, reading with clues 4 - Inspection: CAD drawings, reading without clues A rule that has been around for a long time. It has been replaced as of May, 2016

How to calculate the required display size, the maximum viewer distance, or the expected ratio - Pythagorean theorem (a2+b2=c2)

Viewer distance and ratio are known - Furthest viewer distance / Ratio = Display height Take furthest viewer distance in feet, multiply by 12 to get inches, then divide by 4 or 6 or 8. Divide by 9, then multiply by 18.36 (for 16:9), round up to the nearest diagonal measure for a display. 25’ distance - ratio of 8 25 x 12 / 8 / 9 x 18.36 = 76.5” or 80” display

Display size and ratio are known - Display height x Ratio = Furthest viewer distance Divide the diagonal measure of the display in inches by 18.36 (for 16:9), then multiply by 9. Multiply by 4 or 6 or 8 and divide by 12 to get distance to the furthest viewer in feet. 80” display - ratio of 8 80 / 18.36 x 9 x 8 / 12 = 26’ furthest viewer distance

Viewer distance and display size are known - Furthest viewer distance / Display height = Ratio Take furthest viewer distance in feet, multiply by 12 to get inches. Divide that by the height of the display (Divide the diagonal measure of the display in inches by 18.36 (for 16:9), then multiply by 9) to get the ratio of the room and its display. 25’ distance - 80” display 25 x 12 / (80 / 18.36 x 9 ) = 7.65 ratio

Width & Height vs ratios (16:9) Display size Viewing Distance Diagonal Width Height 4 ratio 6 ratio 8 ratio Inches inches Feet 22 19.17 10.78 3.59 5.39 7.19 26 22.66 12.75 4.25 6.37 8.50 32 27.89 15.69 5.23 7.84 10.46 37 32.24 18.14 6.05 9.07 12.09 42 36.60 20.59 6.86 10.29 13.73 47 40.96 23.04 7.68 11.52 15.36 50 43.57 24.51 8.17 12.25 16.34 55 47.93 26.96 8.99 13.48 17.97 60 52.29 29.41 9.80 14.71 19.61 65 56.64 31.86 10.62 15.93 21.24 70 61.00 34.31 11.44 17.16 22.88 80 69.72 39.22 13.07 26.14 90 78.43 44.12 22.06 100 87.15 49.02 32.68 110 95.86 53.92 35.95 120 104.58 58.82

Updates to 4-6-8 rule due to digital content & higher resolutions ANSI/INFOCOMM V202.01:2016 May 2016 Looks at the detail of the content as well as the physical ability for the eye to pick out details Uses image height, pixel size, degrees of arc, and other factors in the formulas It has two levels instead of three Basic Decision Making (BDM) Analytical Decision making (ADM)

Basic Decision Making Ability to see and read the content in order to make basic decisions Contracts or basic images Uses the constant of 200 for BDM Furthest viewing distance = Image height x BDM x % Element Image Height = Furthest viewing distance / (BDM x % Element) Content can be scaled up or down 90” LCD viewed at 25’ needs 1.5” high text (44 pitch font - no scaling)

Analytical Decision Making Ability to see every detail of a document or image, possibly down to the individual pixels X-rays, photographs, evidence used in court proceedings Uses the constant of 3438 for ADM Furthest viewing distance = (Image height / # vertical pixels) x ADM Image height = (Furthest viewing distance x # vertical pixels) / ADM Content should not be scaled 90” LCD with 1920 x 1080 should be viewed no further than 11’8”

Minimum distance Closest viewer should not be less than the image’s width from the display Provides good side to side view without having to turn your head

View angle The view angle to the top of the image should be no more than 30 degrees up from level Helps prevent sore necks and viewer fatigue

Distance from floor Allows people in the 2nd + rows to see better Image height from floor 24” to 36” for tiered seating or a very shallow room 40” to 48” for flat floor seating Allows people in the 2nd + rows to see better

Too low and too small for content shown (8 Too low and too small for content shown (8.1 ratio) 8’ High screen, 2’ from floor in 65’ deep room

Too high, but a good size for content shown (6 Too high, but a good size for content shown (6.7 ratio) 6’ High screen, 6’ from floor in a 40’ deep room, 23/35 degree

Aspect ratios Ratios PC Monitors (4:3, 5:4, 16:9, 16:10, 21:9) TVs (4:3, 16:9) Projectors (4:3, 5:4, 16:9, 16:10) Ratios expressed as single numbers ( 4:3 - 1.33 ), ( 5:4 - 1.25 ), ( 16:9 - 1.78 ), ( 16:10 - 1.6 ), (21:9 - 2.39) (Monitors, TVs, Projectors)

Screen resolution chart 800 960 1024 1136 1152 1280 1366 1400 1440 1600 1680 1792 1856 1920 2048 2560 3440 600 4:3 16:10 1.33 640 16:9 5:4 1.25 720 1.78 768 1.6 21:9 2.39 864 900 1050 1080 1200 1344 1392 1536

Applying this to a 5,000 sq ft auditorium remodel

Impact of display height

Thank you Timothy A. Dunbar, CTS Director of Computers and Instructional Technology Northcentral Technical College

Analytical Decision Making

Basic Decision Making