Is there any real world equivalent of the power you set a Vue light to ?
for e.g. if I set a spotlight to 100, is that 100W ?
(probably not but it's worth checking)

Ta muchly

Frank

I doubt it. Even though it has a ray tracing engine, I don't think Vue folows a full physical model for light behavior as in renderers such as Maxwell or Indigo.

They do mimic physical behavior of light in things like caustics, but I doubt the light model they are using is going as far as an equivalence in powers.

I base this on practical experience with the results of the rendering engine.

If someone has better details about the lighting model, I would be happy to hear them.

I had a feeling that was going to be the case, I've done a bit of testing myself and it doesn't look promising :unsure:

Indigo looks like an interesting render engine - pity Vue won't export the file type it needs (and then you have the whole copy protected content issue as well to sort out)

If they were going to equate power to a real world unit it shouldn't be wattage which is usually a measure of the amount of electricity consumed by a light.  The light emitted would properly be measured in lumens of light or radiant flux.  Radiant flus is measured in Watts but is the power output not the power consumed by a light source.  Lumens is a measure of the perceived power  and has the advantage of taking into account the human eyes perception of light at different wavelengths.  A good lighting catalogue (the kind used by professional lighting designers) will include this data (you can find it on some lighting manufacturers web sites too).

You'd also want to take into account the distribution from the source of the light generated (usually plotted as one or more polar graphs).  Real world lights don't generate equal lumens in all directions or in the very simplistic way that renderers usually produce spot lights with a simple fall off zone.  I've modelled real world lights from their data using gells in Vue but its hard work converting the graphs into spherical grey scale maps.

There is software that can do all of this and a lot more but it tends to be for specialist lighting designers.  Doing it to a level where the model would really benefit anyone using Vue would be very time consuming.  While we're producing artistic interpretations of our scenes it's probaly not woth e-on's effort and if someone does need to find the luminous intensity on a surface I'd rather they used the real software designed for that work.

For some mad reason I was thinking in terms of Joules or Watt/Seconds but that's a photographic term for the power of a strobe :biggrin:

I really need to get my terminology sorted out heh

I've 4 years of degree building lighting lecture notes and several years of amateur theatrical, band and disco lighting work too and I had to check the units to make sure I got them right.  I was surprised that I had remember lumens and lux the right way round when I was looking :-)

Unfortunately the correct units are rarely used for the the public.  Watts/Second for a strobe is another case of that in the same way as light bulbs only having wattage on - it didn't matter when they were all of the same type but now we use so many types it's time they actually gave us a bit more information on the boxes rather than the silly 20W bulb equivalent to an incandescent 100W bulb.