How to calculate Effective Brightness of several projectors organized in a group ?

Tereza Hrdličková - 01/13/2020 - 0 Comments

Overlay method

 

Overlay method means, you aim several projectors (2+) onto the same area and get a higher brightness of the system (ANSI lm) as a result. The overlay method doesn’t affect image resolution.

Let’s see how the math of overlay works in a 3 projector example. For this purpose, we use 3units LUMITRIX LAZR outdoor projectors, each of them brightness: 6 000 ANSI lm, resolution: 1920 x 1 200 px

 

The math of the overlay is quite simple:

Overlay Efficiency = 95% (0.95)

3 units * 6 000 ANSI lumens * 0.95 = 17 100 ANSI lm

 

Results:

3 units LUMITRIX LAZR combined in an overlay

Effective Brightness: 17 100 ANSI lm

Image Resolution: 1 920 x 1 200 px

 

Array method

 

Array method means you aim several projectors (2+) next to each other with an overlap on the edges, called edge-blend. The recommended edge overlap is 10 – 20% of the unit screen size. The array method increases system brightness and also increases image resolution.

Let’s use 3 LAZR projectors again (6 000 ANSI lm, resolution: 1 920 x 1 200 px), this time organized in an array, and let’s set the edge overlap to 15% (0.15)

 

Aaaaand soooo, we get this:

Brightness

= [units * unit brightness] – [(units – 1) * overlap * unit brightness]

= [3 units * 6 000 ANSI lm] – [(3-1) * 0.15 * 6 000 ANSI lm]]

= 16 200 ANSI

 

Image Resolution Width

= [units in a row * unit width px] – [(units in a row – 1) * overlap * unit width px]

= [3 * 1 920 px] – [(3-1) * 0.15 * 1 920 px]

= 5 184 px

 

Image Resolution Height

= [units in a column * unit height px] – [(units in a column – 1) * overlap * unit height px]

= 1 200 px

 

Results

3 units LUMITRIX LAZR organized in an array with 15% edge-blend overlap

Effective Brightness: 16 200 ANSI lm

Image Resolution: 5 184 x 1 200 px (5K in marketing language)

 

Both methods combined

 

For the sake of this experiment, we will use array method results from the previous calculation, so that’s 3 LAZR units, 16 200 ANSI lm, 5 184 x 1 200 px. Let’s say, we want to double the brightness output, so we use the already existing array and put it into the overlay scheme, so we use 6 LAZR projectors eventually.

 

Brightness

The math of the overlay is quite simple:

Overlay Efficiency = 95% (0.95)

2 * 16 200 ANSI lumens * 0.95 = 30 780 ANSI lm

 

Image Resolution

The overlay doesn’t affect image resolution, so the resolution stays the same as with the original array

 

Results

6 units LUMITRIX LAZR organized in an array and overlay with 15% edge-blend overlap

Effective System Brightness: 30 780 ANSI lm

Image Resolution: 5 184 x 1 200 px (5K in marketing language)

 

ConclusionWith LUMITRIX LAZR system, you can create a screen of any brightness, shape or resolution. You don’t have to understand the math, our experts are here to help you configure your projection screen correctly. Contact us or visit the project configurator.

 

In case you want to read more articles containing math, physics, geometry, numbers, and digital projectors, try clicking right here: The most important number in projection mapping

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