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Saxcore
12-13-2009, 02:26 PM
Hi. I'm currently in my final year of my degree, working on my major project. Working on the whole project myself has meant that I'm teaching myself a lot of the areas I was yet to explore on the fly; rendering is one of these areas! I realise that interior lighting is a pretty largely covered topic, so I do apologise. However, this is my first shot at lighting & rendering a scene, so you'll have to bare with me!

I'm essentially looking for some advice on lighting the attached image. With Jeremy Birn's most excellent book by my side, I've currently implemented an exclusively linked spotlight or two for each wall, the ceiling and the floor. As this technique only lit the room and not the objects within, I've added some Global Illumination and Final Gather. There is also an area light outside of the window, casting the more direct light on the wall and the bath.

I was wondering if there would be a better way to light the objects? GI and FG are extremely heavy for what I need them to do, and I was wondering if I really needed that area light; the only reason I'm using an area light is to loose the harsh edges of the light on the wall. Could I use more spotlights to emulate the bounce light on the objects in the room?

http://samsaxon.placid-acid.com/images/GI&FG.jpg

The image is far too dark, the sink is being lit from behind for some reason, and all models are still pretty much "primitives". Also, the lights haven't had much care with reguards to placement, intensity, colour, etc. However, hopefully you can see past that!

If it helps, I'm working in Maya. :)

Thanks in advance, Sam.
Trauco
12-13-2009, 10:48 PM
What kind of light is the one entering through the window?

It should be mr skyportal with it's light flux pointing inside the room. (and it should just a little bigger than the window opening (and it should be almost touching the wall from the outside).
Saxcore
12-14-2009, 10:05 AM
Hi Trauco, thanks for the reply. The light entering through the window is an area light, emitting photons for global illumination. It's about another room width away from the window on the outside, to avoid over lighting the window frame, and anything close to the window.

Ok, I'll give the mr skyportal a go.

Also, how do I avoid those white dots that final gather is giving me?

Cheers, Sam.
Trauco
12-14-2009, 03:08 PM
Also, how do I avoid those white dots that final gather is giving me?

You need to interpolate between a larger amount of Final Gather points
Saxcore
12-14-2009, 07:37 PM
I've had a bit of go at linking a sky portal to a physical sun and sky; not only did it light my room way more efficiently, it also meant I could get rid of the light that was causing me the white dots!

One question about the portal, however; Is there any particular reason to use it with the "physical sun and sky"? ..I'm currently experimenting with using my own sky sphere, and it seems to be getting results that are more along the line of what I'm looking for.
Trauco
12-14-2009, 08:06 PM
The only reason to use the physical sun is that you want to achieve a physically accurate simulation without doing too much tweaking, or that you have weather data that you want to use, or things along those lines (for example you really want to know how is a building going to look like at 10:00 then at 15:00 and at 20:00 during winter, etc...).

Show us some screens :thumbsup:
Saxcore
12-14-2009, 08:28 PM
Gotcha. For me it actually proved more effort seeing as I already had my lights set up. So it made sense to put my lights back. Ok, I'll put up some more recent renders:

This is what it initially looked like when I applied the portal in the window (after sorting out some dodgy shadows). Much better! Although there is a lot of odd light leaking going on, I think this was down to my original "sun" still being left on. At least we can see everything...

http://samsaxon.placid-acid.com/images/cgtalk01.jpg

After removing the sky and the sun, and replacing them with my original "sun", but with the portal still applied. I'm still struggling to remove the artefacts, and there is still some leaking; however, it is much closer to what I'm looking for now!

http://samsaxon.placid-acid.com/images/cgtalk02.jpg

...essentially my main problem now lies with my area light that I'm using as a diffused sun; causing some pesky leaks and artifacts. I've attempted to remove them with higher interpolation (as well as every other setting), but with little success.

However, it's on it's way!

Thanks a lot Trauco.
Trauco
12-16-2009, 01:59 AM
The problem with your area light is that too much light is being bounced outside your scene from the outer wall (or never hitting your wall and just getting lost in space), so it does produce those artifacts (because theres too little final gather points to interpolate from).

You could encase that area light with a box-like thing so the light that is not going towards the window gets bounced towards it.

I don't remember if you can control the amount of samples inside the area light object, you should look into that. Another option is that instead of an Area Light you could just use the MR sky portal with a blurry small HDRI map, or you could use an array of omni/point lights inside a egg box like construct, made of pure white matte material, and replacing the eggs with omni/point lights (I can't remember the name of that kind of light in maya's interface).

PS: By the way, the MR sky portal is basically a one sided area light.

If you insist on using the area light anyway, it should be smaller than the window opening (like half the size) and not that far away from it. the bigger the area light is, the more spread it's samples are.
Saxcore
12-17-2009, 11:20 AM
Ok, thanks a lot Trauco. I've taken it all on board! For the time being I'll reduce the size of the area light. When I get the chance I'll look into all of the other methods you've mentioned.

Really helpful!

Cheers, Sam.
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