Name: 透視--10分鐘更好的繪畫 - 第9集 (Perspective - 10 Minutes To Better Painting - Episode 9)
Uploaded: 2021-01-14T11:23:00.000Z
Duration: 10 min 23 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

Break out your pocket watch and your paintbrushes! It's time for episode 9 of

10 minutes to better painting! I am your incorrigible host, Marco Bucci.

Let's dig right in. The teacher from Starship Troopers said:

"Figuring things out for yourself is the only freedom anyone really has." This episode is about

perspective, which falls under the category of: depth. You there! Gaze upon

the visit of gods! Well...artists, actually. And they, back in

the Renaissance era, developed something called 'linear perspective.' The basics

of which involve a viewer, whose eye line gets projected infinitely far into the

horizon: this makes a horizon line - onto which we can plot a vanishing point. And

from that point comes a linear perspective grid which you then

reference to ensure your scene has cohesive depth. A single vanishing point

is called one-point perspective. You can have two vanishing points on a horizon

line. Usually these points are located quite a bit out of frame... and you get a

different angle to the scene. Changing the distance between the two vanishing

points simulates various focal lengths of a camera's lens. If you want to look

up at something, add a separate grid entirely and have that grid recede to a

third vanishing point, independent of the horizon line. This is of course three

point perspective, and putting that third point below the horizon line will

simulate looking down. This is knowledge we owe to artists who lived, like, six

hundred years ago - which is pretty cool if you ask me! ...and I bet they're rolling

in their graves. Geez, minute and a half into this

...Thanks. Hey! Get back in your car drive away and then come back again. Jus--just

do it! When he drives away from camera the car gets smaller, and when he comes

back toward camera, the car gets bigger. This leads us to a hidden relationship

between size/distance/and the eye line. This checkered floor will reveal the eye

line (or horizon line). Now, pay special attention to where the car crosses that

line. The eye line tells us that everything above that line is above our

eyes and everything below the line is below our eyes. *psst, do the driving again*.

So, as the intern travels through depth the size of the car changes but its

relationship to the eye line does not. This relationship tells you how to

resize your objects, too. The ratio of the object space above the horizon to the

object space below the horizon should also remain consistent. And of course

that ratio will change depending on where your eye line sits.

I'll move the camera here to show you how some of those changes might look.

In this illustration by Juanjo Guarnido, these two figures are at different

depths in the scene. Our eye line is nicely positioned at ... well... crotch level. I

know this because all the perspective lines traced back to a vanishing point

right at his ... Man, come on, really? *sigh* Let's take stock of the measurement above and

below the woman's crotch. When we translate that scale to our main figure,

who is the same size give or take a few inches, the relationship holds true. Of

course his feet are off-screen. But because the woman has given us the eyeline

reference, the hidden information here can still be resolved! I see a lot

of people trip up here, by simply placing large objects close to camera in hopes

to give depth to the scene. But there's no reference for these objects. I don't

know their relation to the eye line; I don't know how big they are; so it's

basically like they're floating. In the last example I had the information to

complete the picture whereas this time I do not. Speaking of

missing information: when working with depth, objects will inevitably overlap

and therefore conceal other parts of the picture. Guarnido has designed his

picture to give us contiguous slices of the perspective grid, and we then fill in

the areas that are overlapped by other stuff.

We can do this on much less - Dean Cornwell here shows us a few areas where

objects are providing some perspective information. From there we can roughly

extrapolate back to the vanishing points, from there the horizon line, and from

there the viewer can approximate the perspective grid for the entire scene!

Things that touch the ground are very good depth cues because even if an

object gets rotated, creating a custom vanishing point, that point will still

indicate where the horizon line is. Getting back to overlaps: be careful with

silhouettes. This tree overlaps the temple, while still preserving a healthy

chunk of the temple silhouette. Too many overlaps can compromise the silhouette.

This temple now almost reads like a ... *Spooky music plays*. Here's another tricky little thing! I'll call up

some perspective lines, and the unpaid intern. The intern will drive from this

point close to camera to this point a little further away. *rusty engine sound* I ... think that car

needs a tune-up, but let's plot the line he took. It looked like this. Now let's

pull out and have him drive that same path. This time the line looks like this!

Here are those two lines side-by-side. They show us that distance forces

horizontal lines. Take a look at the river that travels through depth in this

Scott Christensen painting. When I analyze the lines that those river banks make

from close up to far away we see a gradual progression towards horizontal

lines. It's like a cypher for a perspective grid that we the viewer can

solve! But a perspective grid is not an absolute requirement. Color and value

alone can deliver depth through something called

'atmospheric' or 'aerial perspective.' ...painting goes over there and over here

I'll draw up a quick chart. I'll plot the colors of the lights on the left and

shadows on the right. Starting with the shadow category, these are colors across

all objects in the painting. And I'll identify the foreground midground and

background sections. There are two things to notice here. One: there's more variety

of shadow colors and values in the foreground progressively less variety

toward the background. And second: with depth, the color is pulled toward the

cyan side of the blue family on the color wheel.

Alright let's examine the light category now. Again, corralling colors across all

objects. The first thing to notice is the overall

cooling of the color still happens ... though the light family preserves its

color more than the shadow family. Also, yellows get filtered out by the

atmosphere. This causes distant colors to appear a

touch redder. When we don't observe these trends and when we don't have a

perspective grid, we can only achieve limited amounts of depth. But just by

implementing some atmospheric perspective, we can make even large

objects in the background recede much further into the distance! This is all

super powerful stuff that we'll explore in part tw--  yeah yeah I was just getting to that.

Hey how did you buy that car?! I don't even pay you.

Alright let's sketch something! I'll start by plotting the

horizon line, vanishing point and perspective grid based on the story I

want to tell. I'm imagining myself high above the ground - like on the second

floor of a building or something. Right around roof level. So when I block my

scene in all the rooftops will be just above the horizon. I'm also picturing

this city kind of elevated off the ground, so that means the ground plane

needs to be put way below the horizon line, which you can see is this kind of

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透視--10分鐘更好的繪畫 - 第9集 (Perspective - 10 Minutes To Better Painting - Episode 9)

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