All language subtitles for 2月29日 (6)

hey everyone welcome to another tutorial

this time we're gonna talk

about gradient remapping inside of nuke

and what exactly that is and how we can use it so

if you guys are familiar with Photoshop you might be

familiar with a technique called gradient remapping

which is essentially just taking

a black and white image like this

and remapping multiple color

values into it so from 0 to 1 0 to 1 so white

being 1 and 0 being black

we can shove a bunch of different

color values into that range

and essentially we can actually do this in nuke and

I don't think a lot of people

are aware of this technique

with the ST map so normally how we use an ST map

you guys should already be familiar as this advanced

tutorial it's basically just for UV

sticking textures onto UV

renders out of CG so that's mainly what it's used for

but we can use it for a variety of different things

so this technique is actually really great

for a couple different things flares skies

fire jet engines

underwater lightfall off and whatever

galaxy kind of space effects you're doing

um so if you have

that I'll pull it open here

so here's a couple different examples visually

so just obviously

guys are gonna benefit a lot from this because

there's a lot of gradiation

in there so we can see some

jet engines have a lot in there so we have some white

going to orange

and then on the very edge just kind of pinkish tone

and even though it almost looks like some kind of white

on the edge maybe some air

or something like that

so these kind of effects really benefit from this

fire is another good one

under water effects

volumetric depends on the camera and the lighting but

even here we can see it's kind of white in the center

kind of falling into a very light

desaturated purple and then into these kind of

bluish tones and then also into these darker tones

so if you were to do that traditionally

you're going to have to stack a lot of

basically radials and color grades and

keyers and stuff like that to try to get that nice

fall off

again lens flares

and all that stuff

so if we get into exactly how we can do this

it's pretty simple

basically I'll just create a scratch one here

put a radio and we'll grab it ST map

and make sure that the ST

map portion is plugged into

the image that you're putting into it

you want to remap the colors

and the colors that you want to remap

goes into the source

so I'm going to take a constant

choose a color and we'll just grab something here

maybe we'll go this

kind of weird color

and plug that into the source

and so what you want to do in here is you want to

go to SD app and switch the UV channels to RGB

and we can check off

one of these channels so it's only going to grab one

basically alpha

from whatever channel you're selecting

so I'm just going to turn off the green channel

just so it's grabbing only the red channel

from this radio

and essentially the way this works is pretty weird

but it's kind of like this

so if I show you

essentially what you put in the

bottom left corner is the black

so if you look here at a radio that would be this area

around and then on the right side is the white

so that's how the colors are going to remap

so if I put this green cube if I put a transform

put it on the left side

and also the way this note is working is kind of tricky

it's only looking at the bottom row of pixels

so if I put the green cube here and I look at it

nothing's going to happen

but if I put this green cube on the bottom

and I turn this and I look at this

you can see it's starting to do something here

so we can see something's happening

so let's put another color

copy paste it stick it in

and let's change the color to

something else

and move it next to it

so again if you remember I said

on the left side is black on the right side is white

so if we look at our picture here

where it's more white

is going to appear more

this purple color

so essentially it's already doing the remap

and if I blur

our colors together we'll get a nicer fall off

so if I just blur the colors a little bit

like this

and now I look at the ST

map we can see that it's starting to do that

gradient remapping effect

one thing you can do is

if you're not liking how the colors are kind

of falling off here

we can shift them around

essentially with these transforms

so if I shift

one of these colors further

over to the left or further over to the right

it's gonna shift

essentially

where those colors are remapping into our 0 to 1 image

so for example

if I want let's go to our image here and we'll mask it

by the radio just so we can see

exactly what that's looking like

so this is what our image is looking like

if I want more green in that image I'm gonna go here

and I'm gonna pull this purple over just a little bit

so we have more green

and they'll just pull the green over

and scale it up

again it doesn't matter what's happening up here

it only matters the bottom pixels on the frame

and I look at this

so now you can see we have more green inside of

that picture

and again I could just take the X translate and

move it back and forth

and I can slide those colors around

how I want

and it's gonna be better if I have

give alphas to these so I'm gonna

use a shuffle note here

and just make sure we have alpha

on both of these constants

so that if they are overlapping

we're not gonna get

put it before the transform there

we're not going to get

some kind of transparent color shift there

so that's kind of what we do

we have just a constant solid alpha

we can translate them

left and right

and that's going to decide

where the colors are remapping in this image

so if I put a transform here

it'll be easier and I can just shift it

if I type negative 50

and I just kind of play around you'll see that

that color is sliding around in our radio

so that's essentially the concept

now of course you can

so I'm gonna go here in this example

so this is the example I had here and I masked it

so that's the example

and I can take the transformer I put after the

the two of these guys

and

shift it around

and you'll see that that's giving you a nice

effect there

so of course you can add more colors

so here's the here's three colors being put in

and again only the bottom pixel matters

so it doesn't matter

if they're not stacked

you can just kind of quickly place them

and you'll get an effect like this

if I turn the blur off

you'll see it's a very harsh remap

and I'm just using a normal radial

and if I shift them around

I can see that does shifting around

in the way that I would expect

and I can blur that together and get a nice result

and mask it by itself

because this is kind of destroying the alpha there

so

just kind of mask it back and get something like that

so

that's going to give us something we can actually use

and make a lens flare or whatever you're doing

and that's going to work for

any black and white image

so again if you have a roto shape

you can remap the roto shape through a feather

so I'm just feathering this roto shape here

we just look at it looks like that

the remap set to the red channel

and essentially that's the effect

so that's pretty cool

some other examples of what I did with this

this is not necessary

but I took this concept a little bit further and

made a quadratic Lumaki tool

so I use this in my nuke 44 class

if you guys are interested in taking that

it's more of an intermediate course

kind of mid level sort of

it's available in the description below

if you're interested

advanced color grading and relighting

but essentially what this luminance key does is

if we open it up I'll just show you what it is

essentially what I'm taking here is the same

gradient remap technique so I'm using the ST map

but I'm using

essentially

rotor shapes with a quadratic fall off inside of them

and this is going to give us a nice

roll off of the highlights

unlike a normal key here

so a normal key here is going to give us

something like this

so if I go here just set these back to the fault

let's say like my previous

tutorials if you looked at my YouTube channel

we're talking about glossiness

on some asphalt

normally you'd have to stack a lot of gears to get

nice pingy highlights

on some rocks like this

so I would have to go here in my

lumens key and I would have to try to isolate okay

let's just try to get the very

highlights on some of these rocks

okay that's gonna work for the very

the pings of the rocks but what if I want some

highlights around those rocks

well I'd have to go here with another key

and do something like this

and then I had to stack these together

and you know it's kind of a process

so basically I created a tool called Quadratic Lumiki

which

kind of does this automatically so it's using this

this

exponential glow

and essentially when you're

shifting the key it's just sliding it left

and right in this ST map

so it's doing the same thing

I just showed you with the colors

except for doing it with this

quadratic falloff effect

and it's really not advanced or anything

if you guys are like tool makers out there

probably looking at this

like it's really simple

there's people out there definitely better than me at

you know making tools and stuff like that

but I think this is pretty useful

for what it is

so basically if I shift that key around

you'll see that not only am I getting some

broad kind of

key in there

but I'm also getting the little pings of highlights

automatically

so I'm not having to like stack a bunch of keys

so again if we go back and compare

we see that's kind of flat

and then we have the pings but they're not together

so this quadratic Lumiki is kind of doing that

and I can adjust the gamma

or the multiply in there as well

and there's different modes that I put in here as well

so you can switch the type of falloff

if you want to play around with that

so this is free

if you guys want to

download that

description below as well

quadratic Luma key

you can open it up and see how I did it

it's basically the same as this but just using

what I just showed

so this is also a really good technique for

remapping pee bubbles sometimes pee bubbles have that

already in there in kind of in the settings

but a lot of times they don't and sometimes you want

a quadratic fall off

in a P mat for example if you're relighting a CG scene

you're gonna want that nice fall off

in your alphas to kind of create lights in that scene

so yeah by default a lot of times it doesn't have

the right fall off you want

so essentially you can take a normal

linear kind of fall off

like this radio here

and I could just chuck on a quadratic Luma key

and just play around the key

and you're going to see that it kind of

gives it that quadratic look

pretty quickly I don't have to do that much to it

so that's kind of how it works

and I can just

switch the mode

and it's going to give me different falloffs on that

alpha

so that's pretty useful as well if you're doing

maybe you're doing a car driving at night

and you want to draw some headlights

normally you'd have to mess around with a rota shape

and it's kind of annoying

let's switch this to RGBA

so this is the quadratic Lumi key

I'm going to pull that out so it has

the effect that I want

some like this

and you see that the way it's falling off

kind of feels quadratic

and you can slide that key around

like this

so the rotor shape

by default does have a couple settings in here

you should probably know if you're an advanced easier

but

sometimes it doesn't look the same way that you want

so

just keep that in mind

and that's basically it so

here's another practical example

I guess of using this

technique so we have a black and white image

and one thing that this technique doesn't like

is super whites

so if you have some values that are over 1

it's going to sort of break so again this

this kind of square

that's searching the bottom pixel

is looking for 0 to 1 values

it's not really

looking for things past 1 but

if you really want to do some super whites

I've played around with

converting the image to log space and then

doing it there

and you can kind of get away with some stuff

so you can play around with different techniques

to do that

but usually 0 to 1 is fine and then

you can grade that image as well as your control image

so if I remap that

to the colors I'm putting in so I have a couple like

sunset type of colors here

I can put a grade beforehand and just essentially

adjust the fall off of those colors quite easily

you see if I go past one it starts to break

so if I put the white clamp

it's going to fix that problem mostly

so if you still push in around it's sort of weird but

generally 0 to 1 is working pretty well

and yeah that's pretty much it

the other thing here so I just

this is another example here so you can see this is

three colors

and that's given this result

and then we can put a fourth color

like the blue in there

and we start to get

some more blue in the shadows

and we have some very like slightly magenta

in the very dark shadows

and I can shift that around

with my transform

so if I shift it around here

you can see

that's how it works

sometimes I use this as like a base image

so I'll use this ST map kind of as like a base color

contamination image

and then I'll just multiply that against the original

so I'm taking the original picture

multiplying that color result

so we can kind of mix the two and get better Lumitz

kind of range there

without having to mess around too much

so that's basically the concept

hope you guys got something useful out of the video

and hit like if you liked it

and thanks so much