True or False

[Pesmerga]

Hey guys, I'd like your take on this. I'm not sure I know the answer to these questions.

1. Everything is lightsource. That's the reason we are able to see. So if every color is light, shadow also reflects its color to nearby surfaces. true or false? (if this is true, I'd like to see some example)

2. Shadows are always the opposite color and opposite temperature of the lightsource. So if there are multiple lightsources (of different color), shadows will be more saturated and the edges wil be doubled. true or false?

3. Shadows don't add. (really?) Some cast shadows can be more intense due to the proximity of the lightsource. So cast shadows do add. true or false?


Thanks. I'm hopping that your answers will help me get a better understanding of it all.

[Pixeldragoon]

1: False. Everything light hits becomes a lightsource in it's own right, in the fact it reflects some light. Like how your chin turns green when you have a flourescent green shirt on. The Sun, which IS a lightsource, hits it, and it reflects that light (as a source), on to your chin. Things that create light;
Lightbulbs,
Sun,
Stars,
Moon would count, though technically it just reflects the sun.

2: I am not sure, but I am tempted to say False about the opposite color thing. Yellow (sun) really isn't opposite of blue(Shadows).
However, it is true that if a light is warm, the shadow will be cool, but if the light is cool, the shadow should be warm. Same with saturation, just substitute Warm and Cool with More saturated and Less saturated.

I don't know what you mean by the edges doubled thing.

3: The term cast shadows don't add, from Prom's tutorial, I think means that they don't "Add blue on top of what is already there", like if you have a highlight on an arm, and there is a cast shadow on the arm, you won't just put the shadow color over the arm, you have to lose the highlight (because it can't reflect a highlight if it's behind something, can it?


Hopefully I didn't make a fool out of myself again.

[DavePalumbo]

1. Light is a form of energy. It is produced by things like fire and electricity, which are true lightsources. It is reflected by objects, though they're not really lightsources as they don't give off their own light. You sometimes see reflected light from an object (like a red tint bouncing off a red wall onto a person's face, or clean white light reflecting off a sheet of paper and onto your hand), but reflected light from an object is always far dimmer than the original lightsource.

Shadows are the absence of light. They are lit, if lit at all, by the reflect light of their suroundings and not by the key lightsource. The deeper a shadow, the less light is being reflected in it. For this reason, a shadow would never reflect light onto another object (unless the other object is in deeper shadow) because the other objects are already reflecting more light that the shadow is. Reflected lights from shaded objects in shadowed areas are generally imperceptable. Technically shadows are reflecting light to you (unless they're pure black), but it's relative to it's surroundings.

2. sorta. Generally, warm light gives cool shadow. This is because the shadows are the absence of the warm light, and so our eyes read it as cool. In the same way, our eyes will read the absence of the light produced by a red bulb as sort of greenish shadow. What we see is all relative to the context that it is in.

3. Shadows, being the absence of light, don't "add". They can vary due to ambient light, though. The simplest way to explain this is repeat what I said above: if you can see anything in a shadow, it's due to ambient light reflecting off of areas which the lightsource(s) can not reach. If you were to block the ambient light from reaching a part of that shadowed area, you would not be adding to the shadow, but simply removing more light from it. The shadow will eventually become pure black in the absence of all light.

[Pesmerga]

Sorry I meant that everything we see is "lightwave" (not lightsource). I know that shadows are the abscence of light. But shadows are also a color. I remember someone talking about this on CA. It was a member's theory. I can't recall his name though. He explained with some cubes how the shadow and the ground were interacting with other surfaces. It was pretty interresting.

[Pixeldragoon]

You mean like how the sky affects the shadow on the ground?

A shadow is an absence of light. So say on the ground, there is a shadow from the sun. It's a shadow from the sun's perspective, but it is still fully lit by the sky. A shadow from the sky's perspective, is at mercy to the dominant color of it's surroundings (relative to how close they are and how much light they are reflecting.)

Right now I sit in a teal room, away from the sun (in shadow) but immersed in the light of the blue sky. I can see the blue in my skin, but when I move my hand into the shadow of my monitor, my hand turns teal.

[Pesmerga]

No, he was basicly saying that shadows actually REFLECT color. I know it sounds weird but he said it. Not me =p

[Sirithduriel]

Pesmerga > what we see are lightwaves reflecting from all kinds of surfaces which is why we see it. However, these lightwaves come only from real lightsources, like those Pixeldragoon mentioned.

Even shadowed surfaces reflect lightwaves, because else they would be absolutely black. Shadows however rarely reflect much noticable light on other surfaces (loss of intensity and stuff) (as DavePalumbo said).

[dogfood]

I'm posting more to solidify my own understanding.

1. I think Sirith nailed this, in that we're talking about surfaces which are not being directly struck by the primary light source (shadowed surfaces, vice actual shadows). The light they strike will be dependant upon the color of the secondary light source striking them and their local color.

2. There have been enormous discussions regarding this and here is what I have gleened from them: artistically, it is much more interesting to have cool and warm counter each other in light and shadows, but in reality, a shadow's color is dependant mostly on the secondary light source and the local color.

3. Dave and Pix said what I wanted to.