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Value

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Transcript

Okay, in this lesson we're going to talk about value. We'll revisit it, look at it in detail and define some things about it show how it works to define form. Then we'll talk about edges, the various kinds and why they're so important to creating the illusion of 3d. Third, I'll render primitive shape to show how it's done practically. And fourth, I'm going to talk about a way to invent value, or shadows on the fly from imagination. So up to this point, planes and rhythms basically give you an idea about the construction of the head.

And what it is you're trying to show. It's a way to understand it to study it. And we've been doing it with lines and it's kind of it's like a diagram. It's like a schematic. It's a study. So the next Step we want to take.

And the next problem we have to solve is how do you show it? So how do you show the human face in the way we want to show it as artists. And that's where rendering comes in. So let's talk about value what it is and get into it. So let's define value. value is the different shades of grey between black and white.

Basically, it's how dark gray or light something is. Now there's a term called local value. And you may have heard the term local color may have not heard the term local value. So let's define that. Local value is the essential value of an object surface without lighter shadow. Now, in truth, an object surface without light or shadow will be nothing if it has no light.

We'll just see black we won't see anything. So I'd like to say it's the essential value of an object without any dramatic bright light showing on it, almost just like ambient light, or the object on a foggy day, okay? So the local value, there's some examples there, it would just be kind of flat. It's that middle gray, let's say of this particular value or these, these three objects. Okay, light and shadow, visually define objects. It's that contrast of light and dark.

The contrast of value allows us to see the world in 3d. So contrast value, super important. So it follows that we interpret the volume of objects based on the light that reflects from them back to us. So Look at that light, defining taking something from flat and 2d shape to a 3d form. Check these out, right we've got the local value, put a little light on it, and suddenly it's 3d. Okay, and there's some anatomy to this and we're gonna get into this real quick.

The big idea here is different value equals different plane. Or another way to say that is, a change in value equals a change in form. So we'll hit this idea, a lot more. But if you can remember that different value equals different plane is the way you get sculptural drawings or sculptural paintings. And the planes that face the light in the same orientation, they get the same value. And they're different from certain other planes that are facing in a different orientation to the light.

It's not that complicated, but it's a great idea. So let's continue on here. And let's look at a sphere. And talk about this now. We talked about the anatomy of light in the anatomy of form. So let's get into some specific definitions.

First of all, you'll be familiar with this we have the family of lights and the family of darks or the light family in the shadow family. And that's the first thing we did when we squinted down to reduce the complexity of the value of the total structure into two separate light and dark puzzle pieces. Now, this is also called the form light and the form shadow The Terminator, okay. That is where the light stops and the shadow begins. So light hits here and travels over the form and it stops here at the Terminator and the shadow begins. So it's where the light and it terminates.

That's a great way to think of it. One thing I wanted to mention is that the part of the object that's most perpendicular to the light, so perpendicular I mean, it's at a right angle to, let's say, the light source, right, here's the light source. Here's the object and that's a 90 degree angle that gets the most light So the part of the object that's at 90 degrees to the light source gets the most light. And that's where the, the specular highlight is going to come, right, it's going to be the brightest part of the object. And nothing else will be as light as that. And you can see, light travels in straight lines.

These photons of light, they're like little packets of light being shot out. And where the light hits the object, obviously, it's the light. And that Terminator again, is just right where that photon is at a tangent, right? Here's the photon traveling this way and it's at a tangent To the sphere, there's that tangent right there. It's a point where this photon or plane touches the edge of the sphere. And those photons travel on, right, the photons that miss the sphere illuminate the ground plane.

Okay? And the photons that get blocked by the sphere and reflected back to us. They leave there's no light, right? So an object that is in basically blocks the light. If there's an object, like this sphere between the light and the ground plane, that object or ground plane receives no light. Okay, so that's that cast shadow.

And there it is. Now interesting about the cast shadow, we can name some parts about the shadow. Okay, the cast shadow has something you may have heard of something you may not have heard of, but it's the umbra. So this area closest to the object that's casting the shadow onto the ground plane. Okay, that's called the umbra. You may have heard that before, maybe not.

And the area that's furthest away from the cast from the object, casting the shadow or the sphere. That's called the Penumbra. And the interesting things about those is that usually cast shadow right the cast shadow of color dx because dx was the animation term for doing a shadow map shorthand. The cast shadow has a hard edge generally. Okay, as opposed to a form shadow that has a soft edge, right there. Okay.

So the umbra that has the hard edge, it's closest to the object, casting the shadow. So it's hard right in here. Okay, let me change colors here. Harder right in here. Okay. And then when it gets away from the object, it starts getting soft.

Okay? It gets fuzzy. And you can see that on light poles right? Anything, when you look at a long shadow outside or even inside, you'll have the hard edge. Here at the umbra, the Penumbra will have the soft edge. Okay, that's gonna make your shadows look really good.

Just that small Hard and Soft delineation of the hard is very hard and very crisp. Okay, and then the soft can be various levels of soft but the longer the shadow, the more soft the edge, okay. Okay, the reflected light. That's the area of the shadow or not the shadow but In the form shadow, so this area here, as you'll recall, is the form shadow. There's going to be some of it, that's a little bit lighter than some other part of it, you see that this is lighter, there's a little bit darker. That's the reflected light, or bounce light.

So these are the same thing. And so what's happening is these photons are coming down. So bouncing off of the object in different directions. Okay? And some of them are bouncing off the ground plane in different directions, right? And some of them are bouncing off the ground plane, back into the sphere.

Okay. Hit the ground plane and bounce into the sphere. And that area of the sphere that's closest to the ground plane, this area and this area, that area is going to be lighter. This area here is going to be lighter because it's closer to the ground plane. Makes sense. So that's why this area here is lit up.

And then there's a gradation where it gets close from light to dark. This area is farther away. this area's farther away so it gets a little bit darker. Okay, so that's the reflected light or the bounce light. That bounce light is never going to be as light as any of your specular light or highlight or half tone in the light side. It's never going to be as light Anything in the lights it does, your values will look confused and you'll get mad.

Okay, so make sure this reflected light is still in the shadows because it's part of the shadow family. Okay, there now is the core shadow, it's the key feature is of the shadows. It's the edge. Okay, and that edge tells the story about the 3d quality of something. Now the thing that makes something look 3d is the light. It's the light reflecting off of that object.

It's not the shadows. Okay, so just remember that. Now this, the edge, the border between the light and the shadow. That edge really is important. It's so important so the core shadow is just before the light at the Terminator complete goes into shadow. It's usually soft.

Okay? The core shadow is soft. It's not the, it's not the darkest part of the shadow, but it's definitely in the shadow. Okay? So there's the occlusion shadow. occlusion shadow is the darkest part of the shadow.

And it's occlusion means to block, it's occluded. So these photons are, you know, they're bouncing around. They're bouncing into the object, right? lighting up the part of the shadow, the bounce light in here. It's bouncing. You know Obviously off the object, lighting that up.

And in here we're getting some bounce light to it's bouncing not only into the objects somewhat, but it's bouncing off the object into the shadow. Right? It's bouncing off the ground plane into the shadow. So it's a little bit shadow, it's dark. But in here, there's no light. Getting in at all, right?

So, in the occlusion shadow, that's the darkest part of the shadow. And no photons are getting into there. So you can see, it's the darkest part right there. And so you'll see that on everything, and you'll see it on the human face as well. So just great to be aware of this stuff. And again, the occlusion shadow you can really see it it's just nothing there.

So It's all almost pitch black, right? Okay. So let's look at some half tones. Okay, as the light is the most perpendicular part of that form towards the light. This is the light object. There's a light source.

And right here, there's that specular highlight that's the most perpendicular to the light source. specular is the brightest, okay, is the hottest and brightest. And on a very reflective surface, it's going to be a really tight white shape. It'll be in the shape of the object or of the light source. So it could be circular. It could be box like it could be Some kind of octagonal shape, it could be any shape, okay?

Whatever that light source is, you'll see it reflected as a specular highlight. And then you'll see all in the light form or the form light in the lights, you'll have the specular highlight and then it gets a gradation getting a little bit darker each time before it goes into shadow. So these are called halftone tones. So you get the specular highlight. Right and then as you move away from that perpendicular orientation, you get the half tones. And in the half tones, you'll have your light half tones.

Just called ht light half tones and your dark half tones. Okay, so you got your specular here. Then you have your light half tones, then you have your dark half tones. Okay, let's make those different colors. Just to make it more clear, if you light half tones here and a dark half tones. That's a lot of information.

It's just kind of good to know like what's going on. You can separate these into like, you know these bands, you have your specular light, half tone, dark, half tone and then your dark His halftone in here. It's almost like steps, right? You're like stepping the value darker and darker and these concentric rings. And I just, I basically, this this halftone you know what's important is the specular is brighter than anything else. And then just before it goes into the form shadow, okay?

That halftone right has to be this area here has to be darker than the highlight and it has to be darker than just this area here. So there's basically three zones and the lights that you can really be worried about just the specular, the light, half tone, right in blue, let's say The light half tone and that green dark half tone. Dark half tone. Don't be confused by that word dark because it's still in the lights, okay, but it's compared to other areas of light, it's darker. Okay, so those are three areas of the half tones, you'll want to be familiar with. And here we are, again.

So just to recap, you have the form light, everything in the light family, then you have the Terminator where the light terminates and turns into shadow. And that boundary at the Terminator we call the core shadow, it usually has a soft edge. And that says that the object the sphere is turning slowly away from the light. If we had a very crisp shadow, it would say That the object is turning very quickly away from the light. And in the shadows we have, yes, the core shadow, the form shadow, the cast shadow and the reflected light, the most important ones that you want to kind of the terms that you want to know the vocabulary that you want to know is going to be the highlight the core shadow, the cast shadow, the reflected light, and in here, we would have the Yeah, the half light, half tones are also called half light.

So really just five things by five terms that you need to know For value and how it turns an object to how we interpret an object that looks like a foreign like 3d, it's the highlight the half light, the core shadow, cast shadow, reflected light, and then you could throw in the occlusion shadow. But as long as you know these five terms right here, you're good to go. Alright, I wanted to point out a couple of important areas about edges and the halftone. Just because before it goes into the core shadow, and you can see here on this picture of Earth, just as it gets dark at the core shadow, here's what I want you to see. You can see the most detail in this area, the most texture, and the most color. All right, so near the contour, the upper part of the earth, it's all washed out.

He can't see much detail, because it's it's the light is just watching washing out the detail and the color. But as it turns towards us and just goes into the before it goes into the core shadow, you can see the most detail color. So that's where you're going to put it. Put your detail and color and texture in your drawing. Okay, let's look at another example. Okay, in this woman's cheek, you can see right where it turns away from the front part of the cheek to the side and goes into the shadow in that core shadow, you'll see that it warms up right so it goes from kind of a washed out white.

As it turns the corner. You see it darkens and value you see a more saturated color, which is that kind of ochre Sienna color, it warms up just before it hits that core shadow. You'll also see the texture and blemishes of her skin. the pores of the skin, you'll see any detail that's there like hair, and so on. So that's where you're going to save your details. Your detail work will be right in that area.

You don't need to put detail everywhere. And that's going to make the areas that you do put detail, much more convincing and have that much more power if you hold back some areas of detail and put detail just where you actually see it. So look for that. I hope that helps. And we'll see you in the next lesson.

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