Hey Welcome to Proko my name is Stan Prokopenko,
嘿 欢迎观看Proko 我是Stan Prokopenko
a lot of you have been asking for a video on
shading. The first thing you need to understand when starting to shade
is how light affects the appearance of form
and how to properly capture 3 dimensional form
based on the characteristics of the light in the scene.
In some of my previous videos I talked about things like shapes, values and edges.
我在之前的一些课里讲过形状 明暗值 边线
But how do we know what shapes, values and edges to draw?
但怎么知道要画什么样的形状 明暗值 和边线？
What exactly are we looking for?
Well, we’re looking at Light
and how it illuminates the objects in our picture.
Light is the reason we see anything and the
characteristics of light can completely change the appearance of the things it illuminates.
So, I like to analyze the light in the scene and try to
capture it, so the viewer can FEEL the light.
Form looking 3-dimensional is a byproduct of correctly capturing the light on the form.
Ok, so I hope I’ve convinced you that studying light on form is important.
Now let’s take a look at all the elements.
For this I’m gonna need an egg.
For this I’m gonna need an egg.
There are two main zones. Light and shadow.
The edge where the form transitions from light to shadow is the terminator.
It’s located at the tangent between the light source and
the form. In other words, just before the planes start to face away from the light.
Lets start by talking about the SHADOW side
There are two types of shadows.
form shadow is a shadow caused by the planes turning away
from the light source. A cast shadow is caused by one form blocking the light from hitting
another form. This egg is blocking the light from reaching this part of the table. You
can find this shape by projecting lines from the light source to the termination of the
first form, and continuing those lines to the obstructed form.
Shadows will rarely be completely black.
Light bounces off objects in the environment and is reflected back into the shadows.
This is called reflected light.
In this case the light will bounce off the paper and into the shadowon the egg.
Along the terminator, sometimes you will see a core shadow.
It’s a darker plane that defines the edge of the shadow.
The thickness and softness of the core shadow can vary quite
a bit. It depends on the thickness of the form, how sharp the edge is between the planes
of light and dark, or the angle and position of the reflecting light source.
Sometimes you won’t see the core shadow at all.
Only if there is something on the shadow side, to reflect back enough light
to create a visible difference in value. This
dark piece of paper reflects less light than the white paper.
You can see a drastic difference in the value of the reflected light.
Also, regarding the visibility of a core shadow,
the reflection has to come from the right
angle. If it’s directly behind the shadow side,
it will create a nice core shadow. If
we move the reflection source closer to the angle of the main light source,
it will illuminate the area where the core shadow would have been.
If you don’t see a distinct core shadow, many artists choose to cheat one in because
it can add to the 3-dimensionality of the form.
Reflected light doesn’t just affect form shadows. It also affects cast shadows.
Less light can bounce into this deep crevice where the egg and table meet,
and so that area gets darker as it goes deeper. This is called an Occlusion shadow.
Moving on to the light zone, immediately after the terminator, is the halftone. These are
planes of the form that are partially hit by the direct light.
As the planes get closer and closer to facing the light, they will get lighter.
And the point where the form points directly at the light is called the center light.
The center light shouldn’t get confused with the highlight.
The difference between the two is that the center light is the plane facing the light source,
whereas the highlight is a reflection of the light source.
A reflection will move depending on where the viewer is.
So let’s say this is the egg.
The viewer, or camera is down here, and the light source is over here.
The center light will be here facing the light source. The highlight however
will need to be at the point where the light can bounce off the surface of the egg and
reach the viewer’s eyes. These two angles need to be equal.
If you’ve played billiards, this is very similar.
To test this concept let’s mark the point of the highlight,
and mark another point for the center light.
Now let’s move the camera and see what happens. Ok, you can see here
that the highlight moved to a different spot, following the camera. The center of light
hasn’t changed. It still pointing directly at the light source.
Don’t let the math of all this confuse you.
Highlights, and also cast shadows which we discussed earlier, can be changed
and they can still look believable.
Nobodys going to call you on a highlight being in the wrong spot.
I can take the highlight on this egg, move it to a different spot, and change the shape.
And it still looks believable…
I’ll often change the shape of a cast shadow
to better describe the form it is being cast
onto. For example if I have an object that casts a shadow appearing to go against the
form. The form of this paper towel roll is a cylinder and to show that I would change
the cast shadow from the egg to wrap around the cylinder.
I usually try to describe the form that the shadow is casting on to,
rather than the form casting the shadow.
So, give yourself artistic license. Learn the rules,
and then learn how you can break the rules to improve your drawing…
Just want to let you guys know, I will be releasing a DVD very soon.
So, keep your eyes out.
It’s gonna have all the video tutorials I’ve done so far,
PLUS a few extras that will be available only on the dvd.
I’m hoping to have it available in the next few weeks.
And as always, if you liked this video,
share it with your friends. They might like it too.
And don’t forget to subscribe to the mailing list on proko.com
to get the latest and greatest tutorials.
See you next week.
明暗处理 光线 以及物体