![]() One exception to this rule, which is becoming more common as the technology evolves, is LED lumens, but we’ll go into that in more depth later. As a general rule, if you see a projector advertised using anything but ANSI lumens, your first reaction should be skepticism. ANSI lumens are the most commonly found unit in projector specification sheets, and also the most trustworthy. ![]() It establishes protocols for setting up a projector at a specific distance in a controlled ambient environment, adjusting the brightness and contrast settings of the projector to uniform levels, and then taking readings at nine specific points to calculate an average (often the center of a projection will be brighter than the edges). The baseline measurement that has been adopted is ANSI lumens, established by the American National Standards Institute’s 1992 document IT7.215. You won’t necessarily be using these units in any practical way with projection mapping, but you may notice them on the Projector Central calculator, so it’s worth noting that while their brightness calculator can be helpful, it’s primarily focused on helping you meet the Society of Motion Picture and Television Engineers’ recommendations for cinema screens. ![]() The imperial unit of luminance, the foot-lambert (fL), measures candela/ft 2 and the SI unit is simply candel a/m 2 although it is more and more frequently referred to as a nit. In photometry, luminance refers to both reflected light and light emitted directly from a source, like the screen you’re using to read this. The materials in the scene you’re projection mapping will all have different levels of luminance or emittance, which tells us how bright or intense they appear to our eyes. If your projected area was only half that size, each of those lumen ratings would produce twice as many lux, and if your projected area was only a quarter of that size, each lumen rating would produce four times as many lux of illumination, and so on.Īny one of those projectors pointed at a white wall will appear much brighter than if pointed at a black wall, as the amount of light reflecting to your eye changes based on the reflecting surface’s properties. 1000 lumens will produce an average of 35.2 lux at that size, 5000 lumens will produce an average of 175.8 lux, and 10,000 lumens will produce an average of 351.6 lux of illumination. Once we know the area of the projection, we can easily calculate the average lux that any given lumen rating will produce within that area by dividing our total light output in lumens by the projected area those lumens will illuminate. When we multiply 4m x 7.11m we have a total projected area of 28.44 square meters. ![]() ![]() With projection mapping, you don’t need to be set up perpendicular to your subject, in which case your frame might be more of a trapezoid than a rectangle, but for the sake of simplicity let’s assume that we are projecting head-on. That means the horizontal width of your projection will be 7.11 meters. Say you wanted to project on a 4-meter tall mural and your projector has an aspect ratio of 16:9. ![]()
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