When Rainman and Einstein meet!
If you know me, you know I like math, a lot! I like Excel spreadsheets, complicated formulas, pocket protectors and spend much of my time alone understanding the world by calculating, just like a physician. While being a punishment for some, it is a hobby for me… Yeah I know but that is just me! I have been affectionately called Sheldon or RainMan by many industry colleagues because they know about my passion for understanding the math and logic behind LED displays. And they also know that I have done my homework and researched the problem well beyond what is needed.
How to know if you’ve got the right size… LED speaking of course!
But one of the questions I get most often is how big should my LED display be? And really the only way is to understand the math and science behind LED displays. To get into this properly we will need two things.
- A generally accepted rule of thumb within the sign industry that states that 1” = 50 feet for text and 40 feet for graphics of viewing distance.
- A calculator. (I told you I like math!)
Most messages displayed on LED displays are now static based graphics with a general hold time of 5 to 15 seconds. Now notwithstanding local regulations and bylaws which stipulate the overall size and, in some cases, hold times, lets complete the example with this case.
Step one – Determining what would be the viewing distance (if the site of your sign is not settled yet)
Simply put the formula is the following:
Speed of the targeted audience multiplied by Time that these people have to look at the sign
should equal Distance where a sign should be installed.
should equal Distance where a sign should be installed.
So, in this case, people are traveling at 60kph (37.28 mph) and we want to have a 15 seconds of viewing time = how much visible distance!
In numbers, it looks like this: (60,000 meters / 3600 seconds) x 15 seconds = 250 meters (820 feet) of viewing distance. So, to have a 15-second timeframe, one should be able to see the sign from a distance of 250 meters.
Step two – How big your should your graphics in order be to be seen
Now for the second part of the equation; how big should your graphic be to be seen from this distance 250 meters (820 feet) away.
Using the imperial measurement system a graphic should have this size:
820 feet / 40 feet per inch = 21 inches of graphic height.
If we would like to have some text you should calculate accordingly:
820 feet / 50 feet per inch = 16.5 inches of text height
So that means, if you ever actually show a peach on the display, you will need to have peach be at least 21 inches in height to see it the distance required. Else, you are simply wasting your money!
The wise guy questions
Perceptive people are probably asking to themselves: Robert, I know now that my peach has to be 21 inches high, but how do I know how much 21 inches is when my display is determined in pixel pitch and resolution? Well, to know that you will have to wait to the next mathematical class.
Trust me it’s riveting stuff. Stay tuned and see you in two weeks!
