[Chris]

Hi everyone, hopefully someone can point me in the right direction.

I only have the stand alone Maxwell plug in for sketchup and not the full suite. I've successfully rendered outdoor scenes, but now I'm trying to render an indoor scene, no windows, so no environmental lighting. I've set the environment setting to none and created 3x colour emitters, red, white and blue (nothing to do with a flag). The blue emitter is set to 40w, 17.6 efficacy, the red emitter is 10w, 17.6 efficacy and the white is set to a whopping 103w and 17.6 efficacy. The red and the blue emitters are used on some small wall lights and I've tried to be clever and set the whole ceiling to the white emitter to light the entire room. What I'm getting is a very dark scene with bright red and blue wall lights. I've made sure that the faces are the correct way too. I have to move the camera EV setting to 3 to get anything like a bright room, but then the red from the wall lights tends to take over the scene. I would have thought setting the whole ceiling to be a white emitter would light the room properly.

What I'm taking a long time to say, and what you've probably already realised is I don't really know how to use the software properly, but I am wanting to learn it. I've looked on the training videos and the forum, but I can't seem to find anything about lighting an enclosed room (ie no natural source of light). I'll keep on playing around with the settings, but I wondered if someone can offer some help or tips for indoor lighting. Greatly appreciated.

[JDHill]

Here is the key:

[...] the white is set to a whopping 103w and 17.6 efficacy [...] I've tried to be clever and set the whole ceiling to the white emitter to light the entire room.

This is 103 watts of energy (really not very much) being emitted from a surface of (depending on the room size) perhaps some tens of square meters. Applied to geometry the size of a normal light bulb, it would be as bright you might figure, but applied to an entire ceiling, the power density is simply far too low. Therefore, depending how many of these smaller lights you have (let's say five lights each, for the red and blue materials), the whole room is being lit by somewhere around 350 watts, which is why you require such an extreme exposure, and why when you use one, the relative intensity of the different emitters seems to be out of proportion.

I would recommend avoiding any lighting tricks (e.g. making a whole ceiling into an emitter) that you would not use in a real life photo shoot. It's definitely possible to go against that advice successfully, but it's not easy, since the result will tend to lack realism.

[Delineator]

I would recommend avoiding any lighting tricks (e.g. making a whole ceiling into an emitter) that you would not use in a real life photo shoot. It's definitely possible to go against that advice successfully, but it's not easy, since the result will tend to lack realism.

Agreed. HOWEVER, if you decide to ignore this, a much simpler way of achieving that feeling would be to group the ceiling, and hide it from GI (right click on selected group, maxwell, from GI, enabled). Then, turn on your skydome and tweak as necessary. This will give it a generic/ambient light sort of feel because the skydome does not do directional shadows. We use this sometimes for quick interior scenes just to throw some light into the space.

[Chris]

Hi, apologies for the late reply, have just got back from a short break, but thanks for the info. I will definitely give the skydome and hidden ceiling a go. Sometimes you don't want to be messing with the lighting too much and as you say, just want a generic light to light the scene. Are there any plans to update the Sketchup plugin tutorials? they use an old interface, and is rendered by exporting to Maxwell render which I haven't purchased. I can tell it's a very powerful product, but it isn't simple to use so keeping these things up to date would be helpful. Thanks for the advice and I'll start playing around again this week.