Help evaluating needed projector brightness


Suppose I want to project on this building :

And assuming we have turned off the lights, do you think a 7000 lumen projector is enough to cover the pillars and windows ?


Here is another one.


obviously it depends on the distance building / projector but in any case i wouldn’t go under 12 000 lumen

@laserpilot’s CA article might be a good reference too:

If you want to properly projection map, you need to measure the amount of lumens per square meter. As a rule of thumb, anything less that 100 lux will look washed out (the ideal range is over 250 but it is usually too expensive). 500 lux is the classical amount of light to be able to work in office conditions.

To calculate your projection area multiply your projector distance by the lens multiplier (0.8, 1.0 etc) and you will get the projection width. The height is derived form the proportion of your projector (16:9, 4:3, etc). Once you have the area, use this formula

lux = lumens / (square meters)

Take into consideration that this formula is modified by lot of factors, including:

  • Surface reflectiveness (can be increased or decreased depending on the material)
  • External light conditions (not only the building lights but also the public lights will affect a lot)
  • Atmospheric conditions (extreme cold, dusty environments, etc)

I hope this helps.

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Thanks for the information guys.