Interior lighting, GI & other settings for totally enclosed spaces: NO SUNLIGHT

[Macho3001]

Hi all,

Could anyone help with posting pertinent links to tips/tricks/tutes on artificially lit (no sunlight) interior lighting settings (using rectangular/omni/spot lights) for totally enclosed spaces (like offices etc). I did many searches on the forums as well as downloads section but didn't come up with any really helpful material. Any help is highly welcome;

Also, I've already been through the Manual but didn't get detailed info about Omnis/spots & specially GI settings for totally enclosed spaces - how to use & tune the rendering engines in consonance with lighting of totally enclosed spaces that DO NOT USE SUNLIGHT to light the scene. For a person who has been using Max (from v6 through to Design 2009) I can tell you Interior lighting of this nature is the most demanding and difficult to accomplish for realistic renderings.

A new thread on this topic in the Tips Tricks section with inputs from all experienced users could really help..

Thanks a ton in advance.

Macho

[nomeradona_cg]

Re: Interior lighting, GI & other settings for totally enclosed spaces: NO SUNLIGHT

macho...

as for my experience. i dont actually use physical camera if im not using the sun. i beleive that camera works well with the strong physical sun. in the case of using enclosed space its best (imho) not to use the physical camera with the following reasons:
1. you dont have to put high mjultiplier values with your lighting
2. you can also play with emmissive lights
3. if you are studying interior lights, your multiplier will always be consistent.

Nomer

[Macho3001]

Re: Interior lighting, GI & other settings for totally enclosed spaces: NO SUNLIGHT

Nomer (Softlight master),

Thanks for your input (more so since I rate you very highly as one of the masters in artificially lit interiors spaces); could you also mention what rendering engines do you consider for such spaces for the primary & secondary bounces, and with what settings which work best for you (It would be great if you could share visopts or put up a small 20 pointer tips (as you graciously did at the P forum which helped a lot all the beginners of lighting), which could mention how and which of lighting.

For spaces which have a lot of cove lighting and recessed area lights in ceiling (both rectangular and circular) what would you suggest as the optimum multipliers settings to achieve uniform lighting levels.

Thanks,

Macho

(On a personal note: I wonder why masters here are not elevated to stature levels here; it would help all users)

[dalomar_cg]

Re: Interior lighting, GI & other settings for totally enclosed spaces: NO SUNLI

1. you dont have to put high mjultiplier values with your lighting
2. you can also play with emmissive lights

Sorry Nomer, but neither one of those are true. The concept behind the physical camera is that you have your lighting at a specific level (physically based is "best") and that you adjust the exposure of the camera to match the intensity of the illumination that you're using. The reason for this is simple...if I'm taking an actual picture of a given space, I'm going to adjust the exposure of my camera to get things looking right. I might be lucky and have lights on a dimmer or additional lights, but the exposure of my camera is still going matter.

Having high multipliers on your lights is therefore specifically a product of the exposure level of the physical camera. So if you don't like high multipliers on your lights, then adjust the exposure. Also, in the case of rectangular lights, multipliers are not tried and true anyway because the intensity is based on the area as well. For some reason no one in vfsu wants to adjust the camera exposure. Its important and it can work for you if you give it a chance

What goes for light multipliers goes for emmissive materials as well. There's nothing about the physical camera that prohibits using emmissive materials.


As for working with very enclosed interior scenes, a big thing is to make the light work for you as much as possible. There are a few pointers (not laws, but pointers) that work well for me...

1. Proper selection of illumination engines. For interiors your really going to want to use IR and LC. LC actually calculates both primary and secondary bounces no matter where you put it, which is the reason I generally have the secondary multiplier at .8...for interiors though I bump that up to .85 or .9...this depends largely on the amount of color bleeding in the scene.

2. Color Mapping. I usually don't mess with this too much, but for interior scenes I like using HVS Exponential. The reason for this is that it really brings down the amount of burning that you'll get from surfaces close to lights. This means that you can crank up a light if you need to and not worry about half a wall being completely white. There is also a little parameter called the Dark Multiplier in there as well. I try not to adjust this if I can, but bumping that up slightly can help some darker areas if you've got em. If you increase the Dark Multipler too much it can lead to a cartoony fake look, so test your settings to see how it looks.

3. Inverse Decay...If you can. Inverse Square decay is physically correct, and the only option for Rec lights, but when I do use point or spot lights I'll try to use Inverse decay. This will prevent the intensity from "dying off" too quick and will add more light as it bounces through the see, but without having to increase lights significantly. I'd still stay way from Linear decay as thats too unrealistic.

Hope that helps

[Macho3001]

Re: Interior lighting, GI & other settings for totally enclosed spaces: NO SUNLIGHT

Thanks Damien

As an architectural firm we have access to IES Lighting data from our manufacturers and we suggest their lights in our interiors. I am given to understand as of SR 1.00.70 & up (to 1.00.74), VfSU can make use of that data for interior renders just as MAX, which is very good news indeed.

I'd like to know whether its a good idea to use the Physical Camera for optimum duplication of actual lighting luminance from IES data as opposed to not using it. We use exposure control (usually logarithmic) to get the best results in Max. If you suggest its use (as you have asked 'why not'), what would you suggest as best (Range) for aperture/Fstop/ISO values for IES based interiors.

Thanks,

Macho

[nomeradona_cg]

Re: Interior lighting, GI & other settings for totally enclosed spaces: NO SUNLIGHT

ok thanks damien for clarification. perhaps i have to emphasize the word based on my OWN experience and not as a rule. call it sometimes cheating maybe. But i just want also to share my personal ewxperience with this. vray has a lot of work around, and there just endless possibility to create things. I knew i have produced good images by just using emissive lights without using physical camera even with the earliest version. because i dont have to crank up the multiplier level and spend testing to adjust my camera exposures. again based on my experience.

I am teaching Photography in my class and i know the physical camera it has all these adjustment that sometimes you will find frustrating.

The above suggestions is to help macho to produce images quickly without having to tweak many things as i knew he has a lot vizualization to do. "call simplifying the program". Biebel one time quoted i beleive in sketchucation " learing vray is by knowing what not to touch yet in the very beginning". you see the program has many things and its really overwhelming in the very beginning. and if you dont provide some quick method, you will end up in giving up. i know because i did.. especially on the very first release because of not having the manual at that time.

i know macho for long time and i know he is use too with the simpleness of Podium, so im placing myself based on his background and context when im writng that.

i beleive both alterantives can still work and produce excellent images but i also beleive that the learning curve for not using the camera yet is much simpler and easier..

On the other hand i know your point, as much as possible you dont want to create confusion ans as much as possible you want to clarify things which is always good. On the other hand, this is also a forum where everyone can offer their experience and opinion which sometimes i know you would realize that there are tons of possibilities.

[nomeradona_cg]

Re: Interior lighting, GI & other settings for totally enclosed spaces: NO SUNLIGHT

macho,

as for the best setting... i think its really depend on the intensity of light. there would be no perfect answer to that, except on just keep on testing which suit you. many times there are settings which are good on one scene and not on the other. vray indeed has a lot of workaround, and its really depend on your testings and preference.

[Macho3001]

Re: Interior lighting, GI & other settings for totally enclosed spaces: NO SUNLIGHT

Nomer,

Big boss ! Thanks a ton mate !!

Macho

[dalomar_cg]

Re: Interior lighting, GI & other settings for totally enclosed spaces: NO SUNLI

I think you got my point Nomer. Its not an issue of how you want to use Vray (thats up to you and not my place to say anything), but rather just telling others without labeling it as "my personal workflow". You'd be surprised at the number of people that I sit down with or correspond with that have misassumptions on how V-ray works based on what was considered absolute advice from others. I typically do things differently than the exact way that I recommend so that people don't get confused with my solution for a given situation and something that is "hard fact" for every situation. I try not to get in all of your way too much, but I'm also trying to make sure that there isn't any misinformation. Sorry if I jumped in to hard on this one.

The quote from Beibel is most definitely true. I find that a lot of users get themselves into a hole simply by clicking without any real knowledge of what parameter A,B,C does. The only way to get around that is to just ask questions and seek out that information (tutorial, manual or otherwise). Gaining the knowledge of what different things do does require that you get reliable information on them... Spot3D.com is a one stop shop for what each parameter does, and its a great resource that I use day in and day out. Maybe a little technical for someone just opening up the program, but a good companion to cross reference a tutorial.


To Macho
There are no set rules for setting exposure levels in terms of specific values, simply because it depends on the amount of light. My suggestion would be to find a specific light source that you can specifically expose your scene to. In most cases for me its the physical sun, and I will adjust the exposure till I'm not seeing any burned areas for light coming through windows. In your case, I'll recommend using the lighting units that we have now, setting the intensity based on levels from an actual fixture, and going from there. Once you've got your exposure level set, you can add lights and adjust their intensity to match the camera. Remember, light intensity is more of a local adjustment and camera exposure is more of a global adjustment. If you feel that you need to make some more global adjustments, then go ahead and work with the camera a bit more.

I've found that most people just starting out with the physical camera find it easier to make their exposure adjustments with the ISO value. The reason is that it has a direct relationship with its values. IOW, lower values equal a darker image and higher values equal a brighter image. Also, the numbers that you set have much more of a consistent relationship to each other.

At this point it kinda sounds like I really recommend using the physical camera. I don't, just use what your comfortable with. Some people don't get the physical camera at all and some use it extensively. If you're comfortable with it, then go ahead, but if it starts to become a stumbling block for you, then you might be better off switching.

[Macho3001]

Re: Interior lighting, GI & other settings for totally enclosed spaces: NO SUNLIGHT

Damien

I have shifted discussion on artificially lit (totally) enclosed spaces here since I will be posting my tests & results in this thread.

Macho

[cat4fish]

Re: Interior lighting, GI & other settings for totally enclosed spaces: NO SUNLI

macho...

as for my experience. i dont actually use physical camera if im not using the sun. i beleive that camera works well with the strong physical sun. in the case of using enclosed space its best (imho) not to use the physical camera with the following reasons:
1. you dont have to put high mjultiplier values with your lighting
2. you can also play with emmissive lights
3. if you are studying interior lights, your multiplier will always be consistent.

Nomer)

I agree. Even sketchup-build-in Sun, i can set sky intensity multiplier down to range 0.01-0.05 ,
then it's almost the normal intensity as physical-cam.

[nomeradona_cg]

Re: Interior lighting, GI & other settings for totally enclosed spaces: NO SUNLI

on the other hand, you have to refer on damien's explanation above the importance of using the physical camera.

macho...

as for my experience. i dont actually use physical camera if im not using the sun. i beleive that camera works well with the strong physical sun. in the case of using enclosed space its best (imho) not to use the physical camera with the following reasons:
1. you dont have to put high mjultiplier values with your lighting
2. you can also play with emmissive lights
3. if you are studying interior lights, your multiplier will always be consistent.

Nomer)

I agree. Even sketchup-build-in Sun, i can set sky intensity multiplier down to range 0.01-0.05 ,
then it's almost the normal intensity as physical-cam.