I see that many arch viz people has taken Corono to their hearts, more than 80% of the gallery posts are arch viz related. Because of that, this might be the right forum - and renderer, to solve this problem/paradox once and for all.
There are various ways to visualize and light with a light fixture.
1)The most used is probably by using a light with an IES profile, to make the light distribution and either use the same light to light the fixture or a material with self illuminating / light emission material.
2) Another way is to model all fixture parts and then use a light emission material to light the fixture it self and the surroundings.
None of these ways are totally correct.
Ad 1) the IES profile is often an "image" of the light distribution sent sent from whole the fixture. That is of course if you are not using an IES profile of the light emitter - the light bulb. Many people place the light with the IES profile in the center of the light bulb and use this as both a light emitter to the surroundings and the fixture itself, the reflectors, the shade ect. This is of course a wrong way to use an IES light. As the IES light is an image of the fixtures light distribution, the IES light will light the scene correctly when it's not occluded by mesh - as the mesh of the light fixture. Secondly, lighting the fixture parts with the IES light gives an incorrect light on the mesh, as the shades are already taken into account in the IES profile. You can therefore use two approaches to deal with this problem
A) to exclude the mesh from the IES light and let it be lit by another light that then only have the mesh of the light included.
A correct but cumbersome approach - and expensive render wise as the amount of lights in the scene doubles. Another problem is that it's not possible to make instances of the light, because of the inclusion / exclusion thing.
B) to have the light distribution "painted" "painted on the mesh " as part of the materials by using a self illuminating / light emitting material
It's hard to paint a totally correct light emission as a material, and an even stronger argument against it, at least when we talk Corona, the light emitting material will contribute to the lighting of the scene on top of the IES light.
Ad 2) by making purely a mesh and then add a light emitting material to tha bulb mesh, you are closer to real life, however it needs that you model all parts in the model (correctly) to make plosible results.
I would hear you guys if you have any ideas how to make a better light source object - maybe a wrapper object that consists of an IES light, and a light that lights the fixtures mesh without contributing to the scene, being able to handle lighting and shadow casting among instances.
What do you think, am I the only one with these kind of needs?
Is it possible to make a thing like this (Keyman)?
At least we need an option on the Corona materials emitting part that disable the emitting to the scene, but glows.
I'm eager to hear your view on this.
