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A general question about lights
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A general question about lights // New Users
Post by dlpeach // Mar 13, 2007, 6:13am
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dlpeach
Total Posts: 22
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Hi everyone,
I have another question about lights - this is more of general question about what each light type does. I'm new to the 3D, and some some fundamental things confuse me. :)
I understand the local light and the spotlight as they seem to mimic real world normal light bulbs and spotlights respectively.
But what do area lights do exactly? I put one in a scene, just one, and left it at the default size it came up at, but it didn't give off hardly any light at all, even at full intensity. So then I scaled the light right up to fit over the whole room, which increased the brightness dramatically, but I don't understand why I should scale the light up so it's huge when a light would only be small, in the real world...? It says in the docs that area lights are good for strip lights or panel lights, but it's not very clear as to how area lights actually work, and how they're different to other types of light.
Ditto for infinite lights and sky lights, neither of which give off much light when just added to a scene as is.
So, am I supposed to scale light objects up and down to change their intensity or just add more into the scene? What is the point of being able to scale the size of the light?
I'm not asking how to light scenes effectively - just asking if someone can give me a little "Light Types for Dummies" lesson, so I can better understand which lights do what.
It's confusing for a newbie such as me. :cool:
Thanks.
Dan. |
Post by Bobbins // Mar 13, 2007, 7:00am
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Bobbins
Total Posts: 506
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Local lights and spotlights both come from an infinitely small space.
Area lights come from the entire area of the light, much in the same way that a fluorescent light in the real world emits light along the entire length and width of the tube rather than from a single point. If you think of a backlit poster in a bus shelter, then that is a good example of a proper area light in the real world that can be approximated by an area light in trueSpace. Due to their size they have much softer shadows than local and spotlights and their brightness is related to both their size and their intensity.
Infinite lights have direction so they can cast shadows but do not come from a single point, they come from everywhere. You can think of them like rain from a cloud - the rain has a definite direction (maybe even at an angle due to wind) but it falls everywhere at once. Hope that makes sense!
Sky lights approximate the way the sky works in the real world. Imagine the light coming from the inside of a large sphere around your scene. The will be one point on the sphere where the main light source is (like the sun) and the rest of the sphere will also light the scene, but more dimly the further you move away from the source/sun.
The only lights that make much sense to scale are area lights and spotlights (and IBL, but you haven't mentioned those so we'll ignore them for he moment!) since it does have an effect on the way the light affects the scene. The rest of the lights can be scaled, but that only helps you see them when modelling: scaling them has no effect on the way the work. |
Post by spacekdet // Mar 13, 2007, 8:26am
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spacekdet
Total Posts: 1360
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Bobbins covered it pretty well and I only have a couple points to add.
When you scaled the area light larger and it got brighter it was because you were increasing the number of 'virtual' lights that make up the surface of the light. Larger area = more virtual lights = brighter/ Smaller area = less virtual lights= dimmer. Think of it as a grid array of local lights- the bigger the grid, the more lights.
Image Based Lights or IBLs work in a similar fashion using the resolution parameters- higher resolution = more virtual lights (and slower render speeds); this time they are arrayed over the inside surface of a sphere that you surround your scene with. Size here doesnt matter so much as the resolution, which is what controls the number of virtual lights in an IBL.
They can also use an image you assign to affect the color/ direction of the lighting. They work with or without an image.
Also, by right-clicking on the intensity slider, you can access a numerical input box that will allow you to boost the output of any light above the value allowed by the slider control. |
Post by dlpeach // Mar 13, 2007, 9:48am
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dlpeach
Total Posts: 22
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Ok, I think I get the area light. You guys mention the number of "virtual lights" that make up the surface of the area light - how are these virtual lights arranged? I mean, if I have for example a huge area light above the entire scene, at which points on the surface are there going to be virtual lights? At every single point? Or are we talking like there are 10 virtual lights, and they are spaced out evenly over the surface? Or are we saying that every single part of the surface emits light equally? Hope that makes sense. :D
The infinite light I'm still not too sure about - so it has direction - I get that part, but when you say it comes from everywhere, not from a single point - I don't get that bit. :confused: What kind of real world light or lighting would an infinite light be similar to?
I'm making indoor scenes, so can I assume that certain lights like sky lights are not really suited to indoor scenes?
Thanks again.
Dan. |
Post by Bobbins // Mar 13, 2007, 9:58am
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Bobbins
Total Posts: 506
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An infinite light makes a fast rendering and reasonable approximation of an overcast sky.When overcast the light comes from one direction - above - and is fairly even over the whole sky. They are also good for when the light source is so far away that the light rays are close to parallel - like from our sun.
Infinite lights are mainly useful to give a low even background light across a scene. This render used an infinite light for the 'sun' shining through the window: |
Post by Steinie // Mar 13, 2007, 10:00am
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Steinie
Total Posts: 3667
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I think of infinite lights as coming from a "direction" just like rain or wind.... |
Post by TomG // Mar 13, 2007, 10:08am
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TomG
Total Posts: 3397
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Infinite lights are also good for simulating sunlight - the sun is so far away, that the light rays reaching us are virtually parallel, which is what an infinite light is - a set of parallel light rays all coming down equally across an area all at once.
With a local light, the shadow of one object will be at a different angle than the shadow from another object, since the two objects will be at a different angle to the point the light radiates from. With an infinite light, all shadows from all objects are at the same angle (just like sunlight, at least on the human scale of the area of space that we perceive around us).
Area and IBL lights create an array of light sources. They are evenly spaced. You can't tell or specify where each light source will go - the area (flat, planar area for Area lights, half sphere or full sphere for IBL) is divided up evenly into a "grid" and local lights placed at each intersection, if you like.
More quality means more lights, means smaller sections, so the light sources move.
You can try enabling volumetrics with an IBL, used to work and make each individual light visible. You could create a sphere just a little larger or smaller than the IBL ring, and see the lights affect the surface, so you can get a glimpse into how they are set up if you want to explore it :)
HTH!
Tom |
Post by dlpeach // Mar 13, 2007, 10:21am
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dlpeach
Total Posts: 22
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Ok - thanks everyone - I'm getting there I think.
I'll go play around with the lights and see if I understand them better now. :)
Thanks again.
Dan. |
Post by weaveribm // Mar 13, 2007, 2:33pm
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weaveribm
Total Posts: 592
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Amen to that thanks all, very much appreciated
Dan one thing to note is that the lighting is very delicately handled in TS and tiny increments can make one perfect exposure (hopefully) just like photography the right exposure is very important and it exists in only a tiny sweet spot. I'll die happy if I ever make a shot like that ^ one. Blimey we've come full circle from PhotoRealism/Magic Realism. Painters painting er, paintings to look like (hyper-real) photographs, here we're making photographs that look like paintings. Probably. And look Ma no paint :)
Peter |
Post by Chester Desmond // Mar 13, 2007, 6:22pm
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Chester Desmond
Total Posts: 323
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Bobbins, that render is amazing. Is that Lightworks? |
Post by Bobbins // Mar 14, 2007, 12:11am
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Bobbins
Total Posts: 506
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Bobbins, that render is amazing. Is that Lightworks?
Yes, LightWorks. It's from nearly 4 years ago so it was probably pre- tS6.6 too. I forget which tS version I used for it now! |
Post by TomG // Mar 15, 2007, 7:32am
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TomG
Total Posts: 3397
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Yes, what has happened over the years is it becomes faster and easier to set up good lighting - but it was always possible (and still is) to simulate just about any sort of lighting in any tS version.
Only difference is it can take 5 minutes to get great lighting today when it used to take 10 hours years ago (and I don't mean render time!).
I am sure with proper placement of hundreds of lights and tweaking all the settings, you could get something as good as the same scene done with HDRI, but it would take a LOT of work! In theory it's possible though - but heck, I would rather save the time, my time is worth a lot to me :)
HTH!
Tom
EDIT - PS that's not really any different from anything else, you could cross America 200 years ago, but it was a lot tougher than it is to do that today, and so on! I guess anything is possible even with the simplest tools, you can build giant pyramids with great accuracy. Just a question of easing the workflow, and reducing the time it takes and work it takes to get there ;) |
Post by weaveribm // Mar 19, 2007, 3:36pm
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weaveribm
Total Posts: 592
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I'm having trouble lighting under Vray and Lightworks I only just (on a meaningful level) :) found that some lights go missing under Vray and also under Vray there seems to be a level of light (too bright) there with all lights off. I can't get the light level down under Vray everything is over-exposed, general mess. Ah (pre-edit) thinking on it the light source that was over-bright was an area light which I now remember reading above (thanks!) that an area light is really many many small light sources as it were and maybe I should make it tiny. See I'm working on it all the time it's dead good isn't it. Eventually :)
So could someone give us beginners some rules of thumb please when running Vray and GI?
And also I see from Vray docs that the (very beautiful) pointilliste sampling leaves textures disturbed in the final render and a little noisy at some settings and I see that in final Vray renders. I know that by increasing something (sampling, photons?)(Star Trek particle beam) I can reduce the noisy textures but again can someone give us some pointers (or links to useful tutorials) on how best to set up lighting for Vray please?
TIA
Peter |
Post by weaveribm // Mar 20, 2007, 2:36am
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weaveribm
Total Posts: 592
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Ah so over-use of volumetric lighting could be part of the answer to my over-bright and sometimes totally blocked screen (all one shade/tone). I always make every single light volumetric on account of "It's got to look better..." doh! :)
Peter
[Edit: will add anything looking to be useful here to save on the spammage]
http://www.caligari.com/News/news_june2004/tipsandtricks.html
Purchased 'proTeam V-Ray for trueSpace7 Course' hadn't noticed that, sweet.
Thanks Steinie below! "You just became an expert!" lol "Where do you want to go today?" Er, home? :) |
Post by Steinie // Mar 20, 2007, 3:01am
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Steinie
Total Posts: 3667
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You have TS 7.1 and VRay....?
Prodigy's tutorial is a great place to start for interior lighting.
http://forums1.caligari.com/truespace/forumdisplay.php?f=61
Master Parva's Tutorial sold by Caligari will take you to the next level:
http://www.caligari.com/products/trueSpace/ts5/Courses/newvray.asp?Cate=Training&SubCate=Master
You just became an expert!;) |
Post by Cthulhu // Apr 3, 2007, 7:36pm
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Cthulhu
Total Posts: 48
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Howdy all. Long time, no post. Here's a simple scene that illustrates basic light usage (using locals, an infinite, and area light). I made it in tS6.6, and have included scenes for 5 and 4 just in case. I made use of the object note editor in tS6.6, so you can click on objects and see notes attached giving descriptions of what each light is doing if you have that version (or above, presumably).
Basically there's an infinite light for direct sunlight, an area light in the window for indirect light from outdoors, a local light in the "sunny spot" on the floor to simulate light bouncing from there, and two more local lights simulating the lamp.
It helps to turn on only one light at a time to see what it's doing in the scene. Experiment and have fun. :)
5145
5146 |
Post by Bobbins // Apr 4, 2007, 4:35am
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Bobbins
Total Posts: 506
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Nice one. In these days of GI and HDRI it's good to see somebody else who still remembers how we used to have to do lighting. As long as it looks 'right' then few people will ever stop to examine if it really is accurate. One thing to remember is that even though it might take a little longer to set up a scene with lighting like this, it will very often render much more quickly than using GI. |
Post by TomG // Apr 5, 2007, 3:39am
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TomG
Total Posts: 3397
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Very nice work, thanks for sharing! Should be very educational to look at.
The pro to this approach as noted is that the render times can be faster. The con is that the set up time that you put in can be longer. GI is popular because most people don't mind their computer having to spend extra time doing something, compared to themselves having to spend extra time doing something ;)
Of course it is the end result that matters, not how it is done, and there are many ways to get to a good end result. Take whichever you need and prefer is the answer. So it is good to see this demo of how things can be done without GI / HDRI and similar.
Thanks!
Tom |
Post by Bobbins // Apr 5, 2007, 5:45am
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Bobbins
Total Posts: 506
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Ahh, but the main benefit is that this manual approach to lighting works in all versions of tS - and other CD programs, no matter if GI is available or not. |
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