Photon Aquarium is a physically based rendering engine that is able to calculate Photosynthetically Active Radiation (PAR) and Lux in a virtual aquarium.
Easiest way is mailing me spectral distribution, wattage and lumen for each lamp. All three must be specified. High resolution spectrum is a plus.
That's correct. The algorithm used is stochastic progressive photon mapping that refines the output forever. You will have a good PAR/Lux value within a couple of iterations in most cases.
That is because you look at the back of the walls surrounding the aquarium where no light reaches. In the future I will make it possible to disable them. PAR/Lux will be correct since the square light probe will see the light sources.
Right click on the lamp in the lamp table and select "Remove reflector".
That is because they are created in the exact same spot. It is important that you move them apart for the PAR/Lux values to be correct, otherwise photons escaping one of the lamps might hit the others. In the future I will probably randomize the initial locations a bit.
That is because each light bounce in glass+water will split into two separate rays - which adds up quickly to insane amounts of rays that needs to be traced if the whole view is mostly glass+water.
How to create a spectral distribution picture for the calculator:
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