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JA-forreal
05-20-2003, 08:18 AM
Lighting Array GI vs Plugin GI
I find that with all the plugins that simulate Global illumination I still mostly use old fashioned 3d lighting arrays. I use a soft spotlight as the main duplicated light and a "sun" light or other point lights for other environment light effects. Maybe it's because I am so used to using those light setups. These setups can produce quicker results than plugins as they require less tweaking.

I see that most new 3d software users want the auto GI lighting type features. But I find that they are not always clear as to what is going on behind the scenes during a render. Their renders often have that "GI look". I like the photoreal properties of GI lighting but that in itself can lead to a reliance on the computer to prepare lighting. Real life does not look manufactured, though 3d scene renders that rely on automatic computer lighting alone do.

I think that it is only when an artist can maintain control over every element in a 3d scene that they produces the best artististic renders. That control also is also connected with the computer hardware. You can ontrol exactly what is in a scene and how long it takes a pc to calculate that scene to render. The more plugins that are in place , the more a computer handles it's own calculations. Thus longer renders, and less predictable results.

Any thoughts on this? It would be great if one of our cg lighting science pros here on cgtalk stepped up to the "mic" to shed more "light" on this subject.

CG lighting is such a deep subject and the more complex you make it or need it to be, the harder it becomes to work with.

I have been working on adding more lighting elements to a city scene. I have come up with some suprising results and some suprising total disasters. CG light exploration is rewarding in any case.
Khepri
05-20-2003, 09:31 AM
not to be a ass, but this subject has been in here quite acouple of times now.

people that use the default "plugin GI" will have work that looks like everything else, but you have a vast array of subfeatures(at least in brazil r/s) to control/customize the final outcome of your render. that, and the speed, since calculating 70(to name a number) shadowmaps takes time, and GI being more accurate.

the "plugin" GI has alot of pros, and saying its slower than normal lightarrays is a bit odd, GI is Raytraced... shadowmaps are not(unless you use raytaced shadows off course)


do a search on the forum to find more oppinions

cheers

Roderick
joconnell
05-20-2003, 10:08 AM
Only benefit I find with GI is that you can get good looking renders with a minimum of setup - Unfortunately you pay the price in render times. Light arrays are far more difficult to set up (unless it's a simple skylight) and you don't get the same nice contact shadow that you get with GI but you do get much faster render times. Plus all of the render passes that most scanlines support - something that is lacking in a lot of GI renderers...
JA-forreal
05-21-2003, 07:24 PM
Light arrays are far more difficult to set up (unless it's a simple skylight)

Most 3d softwares like Maya, Lightwave, Blender and Max support simple array copy tools. The process involves parenting a spotlight to a sphere and making sure that all the lights aim to the center of the sphere. The original duplicated light must be set to a low level. Also, the original parented spotlight must be set to softshadows. Your GI sphere will have as many lights as it has vertexes. Tweak, tweak, and Tweak. Then you use a main key light as the sun or dominate light source. I find that setting up a lighting array is as easy as setting up a three point lighting system. The difficult part is getting the results that you want at render time. This process could lend itself to an indepth lighting disscussion.
joconnell
05-22-2003, 01:47 PM
As I said yeah a skylight is easy - it's any other situation besides a skylight which is time consuming to set up. There's a tonne of scripts for max that make a light dome either with or without a bitmap for its colour value but as you mentioned it can be made just as easily with an array tool or some simple parenting and ducplication. But say for example more complicated interior bounce lighting - that's where it gets more tricky. Plus the different shapes of shadows that you can't get without clustered shadow maps or adding area lights. I always find that the best thing to do is render a grainy low res GI Image with bounce light being calculated and then use that as your guide for a faked light setup...
JA-forreal
05-23-2003, 12:22 AM
as you mentioned it can be made just as easily with an array tool or some simple parenting and ducplication. But say for example more complicated interior bounce lighting - that's where it gets more tricky. Plus the different shapes of shadows that you can't get without clustered shadow maps or adding area lights. I always find that the best thing to do is render a grainy low res GI Image with bounce light being calculated and then use that as your guide for a faked light setup...

Yeah that is true. That bugged me with Blenders lighing setup. Then I found out how to setup my GI Dome lights so that the light shines through all the walls and other surfaces but the showdows still behave naturally on the objects. It looks sweet. It's not a scientific setup but to sure looks "mighty pretty" there partner.

Where did that come from?

Above all, it test renders at 320X240 in seconds. For final renders at 1280X1024 depending on how wild I go with the amount of lights, take only a minute to a few mintues per frame. This leaves room for particle effect calculation and other render additions, plugins, etc. I am a former Max user myself and for my 3d goals Max didn't quite "stack" up to my little production setup in the area of rendering efficiency. It was a little to slow for my taste in some areas. I can't complain, now I find Blender a little slow in some areas. That's why I stand on the soap box over at blender.org, maybe some of my cg rants will spark up a new Blender software feature developement. But any 3d app can blossom if you take time to play with the tools. Try using only a limited amount of soft lights to create more dramatic looking lighting. It took me over two months to plan out a new approach to update my old lighting techniques. And it was worth it.

Still, a three point lighting setup is my favorite. The Fake GI setup is a must for more complex settings like a room or a city street environment. An you must always work with reference pictures to get things looking just right.

I wonder how fast I could render may faked GI scene on couple of those new AMD chips running with 16 gig's of ram'mola. It just might be a slight bit faster what I'm used to. HeHe.


-As for now, remember, machines don't run people, people run from machines.
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