Indoor light issues

tdc

Can someone point me in the direction of a good inside lighting tutorial or tell me what I am doing wrong/missing? Anytime I use any sets or interiors, I can't seem to get rid of the noise or grain. No matter how I try it always looks grainy. Is there a fix? Is there some setting I am missing?

Thanks in advance for your help

 

Richard Haseltine

How are you lighting your interiors at the moment?

tdc

Ambient and distant light and everything in between. I even purchased ghost lights to try and help. They do... but there's still a lot of grain 

Tobor

The noise is from underconvergence. It takes longer for all the pixels to converge (an interative process requiring many successive samples -- hundreds or thousands to each pixel) when using indirect lighting.

Too, some types of lights are more efficient than others. An ourtdoor scene lit with the Sub/Sky or an HDRi in the Environment dome will tend to render the fastest, followed by the "built-in" light types (Point, Spotlight, Distant), and finally emissive sources, which is what the Ghost Lights set is.

Options:

1. Lop of the ceiling, if you can. The first movies were made on outdoor sets, as film then wasn't very sensitive, and the actors tended to die from the heat if using lights in closed studios. Since they were silent movies anyway, it didn't matter when an airplane flew overhead. You can use the same technique if the interior has a removable ceiling/roof.

If not, you can try the Iray Sectioning Plane feature. It's a little complicated to reiterate here, and there are several threads in the forum on using it. What it basically does is cuts a plane in the geometry so that light can pass through.

Barring that, you can try removing the ceiling using the Geometry Editor. "Paint" over the geometry to remove, and choose the right-click option to hide the selection.

(You can also do the same with walls behind the camera that aren't seen.)

2. Try to aim spotlights or distant lights lights directly through windows and doors, so that the interior gets direct illumination. Don't just rely on there being light outside somewhere.

3. Turn on the Architectural Sampler option. Indirect lighting is what it was designed for. It's a helper that gives Iray some (decidedly biased) hints about the lack of direct lighting in the scene. Overall the sampler slows down rendering, but in the right circumstances, it can still be faster than using only indirect light.

4. Add a light (sky) portal, a feature new in D|S 4.9. Like sectioning planes, their use is a bit peculiar, so do a search into the forum for the steps.

5. Finally, those invisible mesh lights in the ghost kit can provide direct illumination when other sources are impractical, or don't yield the look you want. The two issues with emissive lighting are a) it's not generally as efficient compared to a properly set up environment dome or the built-in light types, and b) its light is always diffuse (non-directional) unless you use an IES profile.

Because of the former, your renders may still take longer than those when lit outdoors, as Iray has to calculate a more complicated ray path; and because of the latter, will not have highlighting that helps to model the character. Look at your Outside render: it's more realistic, and IMO pleasing, because there appears to be a light source on the model's right side. To replicate this with mesh lighting, you'd need to either add an IES profile (lots of trial an error), add another ghost light turned up way high right next to the character, or introduce a spotlight or other directional source that can impart the highlights. I usually employ the last option.

 

tdc

Thank you, Tobor! Thanks for taking the time to explain all this. I will take your advice and see if I can experiment more with sets. I feel more positive now with the list you gave me that I can improve my renders.

Cheers

 

Richard Haseltine

Make sure the lights you are using are in fact Iiray lights. if by ambient you mean the Advanced Ambient Light by Age of Armour that is a 3Delight shader, not Iray. The stock DS lights from the Create menu are Iray, anything else that is for iray will probably say so in the title.

Ostadan

Tobor said:

1. Lop of the ceiling, if you can. The first movies were made on outdoor sets, as film then wasn't very sensitive, and the actors tended to die from the heat if using lights in closed studios. Since they were silent movies anyway, it didn't matter when an airplane flew overhead. You can use the same technique if the interior has a removable ceiling/roof.

Of course, in the early days of film making, there weren't a lot of airplanes flying overhead anyway.  It should also be mentioned, though, that for 'indoor' scenes that were sun lit, a translucent sheet (like a bed sheet) was sometimes used to take down the hard shadows.  In one of Baum's 'Oz' silents, you can see this pretty clearly as the wind was blowing that day.  In Iray, of course, if there's no ceiling you can use HDRIs that resemble studio lighting anyway.

By the way, two industries flourished in Southern California because there are so many sunny and clear days every year: film (moved to escape Edison in New York and his patents) and aviation.

Tobor

Ostadan said:

Of course, in the early days of film making, there weren't a lot of airplanes flying overhead anyway. ...

By the way, two industries flourished in Southern California because there are so many sunny and clear days every year: film (moved to escape Edison in New York and his patents) and aviation.

All very true. By the late teens my step father's family moved from NYC to Hollywood for this very reason (the studios, not the airplanes). When Laemmle and other bosses uprooted to Hollywood, so did most of the production workers. (My step father's father was a cameraman for Universal, RKO, and others.)