Interior Lighting causing problems

[Jayceyned]

Hi Guys,

wonder if anyone can help; I work in designing domestic appliances and have to render the inside of large fridges quite often, and we always seem to have issues lighting the inside of the fridges nicely to show off all of the nice features that we are suggesting. The fridge typically has an internal white plastic 'carcass' for the walls and ceiling, and lots of transparent glass shelves as well as a few other bits and bobs. We model in physical blocks for the light sources (ie. a strip at the top and one either side inside the fridge), and have tried a variety of methods to illuminate the inside; none of which have yet been successful. The best result that we can get is to render with no internal light sources and simply selectivly brighten the output image using Photoshop.

I will list the attempts and reasons they're not good enough below and hope that someone has another clever solution / has experienced something similar?

Please help:

Attempt 1: Make the light sources that are modelled into the fridge (one on either side wall facing inwards and another on the ceiling) emissive material type and increase intensity above 1.
Issue: This illuminates the interior but not enough and bright light flares are seen all around the light sources on the rendering.

Attempt 2: Make fake light planes within the inside of the fridge (floating in free-space between the shelves), make them emissive and make set them to not visible to the eye or in reflections.
Issue: This illuminates the interior enough, but bright light flares are seen at the edges of the 'light planes' on the inside walls of the fridge. I have tried playing with the planes so that they are not close to any walls but it seems impossibe to acheive an even lighting.

Attempt 3 Make small spheres, again floating in free-space, inbetween the shelves, and again make them invisible to the eye and in reflections; again these 'light bulbs' have been turned emissive and the intensity increased. This has also been tried with small elliptoids, of various sizes.
Issue: Again this illuminates the interiors nicely but bright light flares are seen near the 'bulbs' on the inside walls of the fridge.

Attempt 4/b] As above bus using may tiny spheres like LEDs in free-space.
Issue: Illumination is not great enough.

Attempt 5 Make a large light plne outside the fridge and shining directly into the interior of the fridge, again invisible and emissive.
Issue: The inside is illuminated but the light is totally unnatural as the light plane blocks out all of the nice light pattens created by the HDRI map.

Attempt 6 Copied and offset the inside of the fridge walls and ceiling by a tiny amount, and turned the surface invisible and emissive.
Issue: All internal fridge walls become blown out white.

I ran out of ideas; but won't stop trying.

Thanks guys, I really appreciate you reading such a long and detailed post (aka boring).

Jay.

[elliasp]

It would be great to have some screenshots to understand what you need and your problems... 

[Jayceyned]

Hi again,

just wanted to post some images of what I was talking about; hopefully illustrates the issues a little more:

Attempt 1:


Attempt 2:



Attempt 3:


Attempt 4:


I don't have renders of the other attempts to hand but similar issues occurred.

[elliasp]

Ok, now I understand the problem.

First, Keyshot has a problem about invisible emissive materials : they produce shadows.

I already posted about this but no one answered me.

Anyway, for your problem, I learnt 2 or 3 things which might help you :

- First, the level of lighting in the emissive material panel is not only till 5000.  If you want, you can type 1 000 000 (it's a very strong light but you can do that).

- use "indirect lighting" in the real time panel

- remember that Keyshot is acting like reality : that means if you want to illuminate your fridge, think reality : you will have to create a lamp, like in a real fridge.

- your light will never be a perfect gradient in real time render : it takes a lot of memory for additional lighting, so the computer show you some grainy white things to simulate the light. But in the final render, you will have a perfect gradient.

So, my final advice will be to create the reality : a lamp, like in a real fridge, because Keyshot is acting like reality...

And of course, if you have some glass parts (and if you want the light travel through these parts) you will have to increase the level of raybounce until you see a change).

Bu the first part is : think reality : create your lamp (even if it's a led : create a plastic ball with an emissive object inside).

But more you will be realistic, more the level of raybounce will have to be increased, wich mean a lot of render time.


SECOND SOLUTION : do what professionnal photographers do when they have to shoot a fridge : convert a complete interior side into emissive material (the interior side we don't see)...

So, you will have lighting coming from the right, I sent you an exemple below...

Hope it helps :-)

+++
F

[elliasp]

On the last photo, you can guess it's all the left side wich is emissive ;-)

[Jayceyned]

Thanks so much Francois,

I have to say I've tried everything that you mentioned, bar the last option which seems like a great idea. I will give it a go and post up the results in a few days (once I get some time to play).

I didn't know that there was an issue with Keyshot producing shadows from invisible objects but it's not obvious that that's what the issue is.

Thanks again for all you're help,

I think you've cracked it.

Will let you know how I get on,

Jay.