Is there a way to use a light inside a sphere to simulate global illumination so it produces light and shadows (excluding shadows from the sphere it’s in of course)
I’ve played with Indirect lighting and had the balls emitting light which looks nice, but they don’t cast shadows which Nick also point out for C4D and that’s why he does that trick with a light inside the ball to help producing light and shadows, but he excludes the sphere from the light, so the light shines out from the sphere and produces
shadows on other objects.
It would be so cool if we could do something like this in 2.5 :yes:
Two sphere here. One is red opaque one that is standard. The other, glowing one has material with Emit value on it. That makes it glow. Also “Traceable” and “Shadowbuf” settings are turned off. So when you put the lamp inside, the light goes right through the sphere wall to light up the room.
Had a play with the most recent version of 2.5, came up with a so so way of doing what sounds like what you’re after. This method does not use global or indirect lighting, tried to basically convert what they did in C4D to Blender. Got 50/50 results but it was the best I could do.
Attached is a screenshot and a blend file which hopefully you can pick apart.
The 2 important settings for me were:
an objects translucency setting. By setting this and putting a light inside the sphere, the color of the light changes the color of the surface of the sphere. So even though it appears that the sphere surfaces are different colors, they aren’t, they are all white, but the light inside each sphere is a different color. Because translucency is set, backlight color gets transferred.
The other thing I did to make it so the light inside could still cast shadows, but not see the sphere was to set material for the sphere so that the traceable option was turned off. This is not a good thing but if all you want is light spheres this can work.
The scene has shadows, it doesn’t have atmospheric glow though that would be something to do in the compositor, BlenderGuru site is a good one to cover that.
There has to be better ways to get this effect though because it’s slow and disabling traceable is a pain. If you are ok with the compositor I would say do your shadowing using the compositor rather than how I did it in the blend file, would be so much quicker.
If the blend files aren’t clear and you need a run down i will try and write up a tutorial but it’s at lot of words for something that’s not the flexible anyway.
When I say it is not very flexible I mean because of the traceable option and the fact the it would be better to use proper indirect lighting when emitting mesh objects finally support shadow casting (which they should or we complain loud to the Blender DEVs :P)
Thank you both, great results from both of you :eyebrowlift:
AIBlender, your spheres looks perfect, both glossy, shiny and looks like they produce lights.
I see what you mean with “not very flexible” but it works, rendering takes forever, but looks awesome.
And as you mentioned, emitting mesh with shadows will probably soon be available as well.
But this is great learning how things can be done to produce this specific effect.
Did a bit of correction on the blend file I somehow accidentally set the soft shadow sample sizes way to high, i put them back to 6 on each of the lights in the spheres, now it renders at something approaching normal speed.
“The trick,” if there is one, is that “physical reality has almost nothing to do with it.” :eek:
“In the real world,” a sphere that appeared to be “glowing” would of necessity be “a source of light.” Therefore, your first (and perhaps, un-tested) assumption, when trying to translate that into the world of CG, is that “you must re-create that physical reality.”
Well… you don’t.
A “glowing sphere” is merely a sphere whose surface pixels have a certain, “bright,” color that has nothing to do with whatever lamps may surround it. It appears to be producing a light of its own. To your human eye, armed with your physically-based assumptions about “how things work,” it does. But to the computer, it doesn’t have to – and it’s far better if it doesn’t.
The “glowing sphere” determines what the sphere looks like. The second aspect, “what it appears to do to its surroundings,” can be handled by an appropriate, but ordinary, lamp (or lamps). Furthermore, thanks to compositing and other node-based techniques, if it needs to appear to exert “more than one influence” upon its surroundings, you can deal with each one of these separately.
One thing that was drilled into me as a nascent photographer was: “look at The Light.” Not the scene… not what the scene was supposed to depict… the light, itself. I have seen “the lovely sun-lit interior of a hotel” created at two o’clock in the morning on a moonless night (chosen for that very reason).
When regarding a scene (or considering how to create it), consider “why” the light might be the way that it is, but don’t feel in any way obligated to re-create that real-world “why.”
Here is my attempt. No nodes needed. You control the light by altering the alpha of the sphere’s material. The light leaks through as it should. Shadows and reflections are intact.
I had to remove a sphere to get the BLEND to upload. Blender 2.5 file size has increased but our file attachment limit has not!
