All language subtitles for 2月29日 (8)

to part 2 of the UV

ST map tutorial

sorry it's been a couple weeks

I've been pretty busy but

more content will be coming a lot more in the next

few months here

so this is kind of

our part 2 to this video

I hope you guys have checked it out

this is UV

basically

part 1 for the CG objects and how we can use it

and you might recognize this pattern here

this green and

red that you saw wrapped around our CG objects

so we're gonna actually take that concept and just do

some of the things that we can actually do in 2d

with this and we don't actually need any

CG rendered out for this

we can do it a lot with an expression node and a

couple different things we can do that are

kind of interesting with it

so if you get straight to it

we have an expression here and the way we create this

basically pattern

is with this expression so if you put

apprentices x plus point5

divided by width

and we see that that's going into the red channel

and y plus point5 divided by height

and essentially what that does

so if we take out

if we look at the red channel on the width

so I hit R on my keyboard

and check out what's happening

we can see it's creating a

0 to 1 ramp in the red channel

and if you look at the green channel

which is the y and the height

we're seeing a 0 to 1

ramp being created in the green channel

so naturally we get a red and green

kind of combination

which is creating the yellow up here

and that's what that's doing

and you're asking well what is that doing exactly

it's just creating this picture

essentially

the way you want to think about this is it's a 2d

coordinate grid

it's telling nuke

where pixels are on this pattern

so if we just pull the picture

really simple just like an X y grid like this

basically if we are to

create this pattern

and we move some of the pixels it's going

to understand how to transform them

so if that's confusing you

we're going to show it in just a second here

but that's kind of what this is doing

so we have that expression and now

we're going to go and see what we can do with it

so

if we have a normal picture we just have a grid here

close this stuff

and we have that expression over here

which is creating a UV coordinate

basically if we apply a transformation to our

coordinates so I took a grid warp here

and I just kind of pulled some of the points like this

and then I've applied a transformation

and kind of scaled it up

and just rotated it

a little bit

if we plug that into the ST map we can see

that's actually being applied to our grid

so even though these two effects here are going on this

picture it's being applied to

basically through this ST map to our grid

and you might be asking a question

well why can't I just copy these

and just plug them directly into the grid

and you can actually gives exactly the same result

so in this instance it's not that useful

but it demonstrates exactly how it's working

so no matter what we do to this picture

it's going to be applied to

our secondary or primary source

so

furthermore we can look at how this actually

starts to become useful

so we have this picture here

which is the same we've been starting with

and another one

and what I've done here is applied some basic

warps to them

so I've kind of shifted you can see these dots here

I shifted them upwards

and if I open this grid warp

I've shifted these ones in right

in the direction

so now what you can actually do is apply the ST map

and we see that this warp is being applied

but what I've done is put a dissolve between the two

so right now it's only looking at this one

but as a dissolve animates so I set a keyframe at 0

and I set a keyframe at 1 on the frame 30

can see that if I scrub between the two

we're actually morphing between these two

transformations seamlessly

so that's really useful

because you could do a complex morph

have all of your predetermined

positions set and kind of

dissolve between a whole bunch of them

so you could have another one here

I could plug in this and

keep dissolving all the way between the

3 or 4 or infinite positions that you have

so that's really awesome way that you can use that

further

you can and probably the most common use of these

UV coordinate images

is bringing in

or saving lens distortion profiles

so if you guys have done CG composing you know that

we're pretty concerned with

matching or removing

let's say lens distortion from footage

or applying a lens distortion to a CG

object to match the footage

so if you're solving a 3D

track in another software and there's

other softwares like 3D Equalizers Synthized Blender

they all have this feature

you can remove

or solve the lens distortion

it will actually give you a picture like this

which is the

UV coordinates with that warp applied to it

so to give you a visual

understanding

we have a checkerboard here with a simulated

lens distortion

you can see that the lines are starting to

curve around the edges

if we have it off you can see they're straight

and we have it on you can see that it's distorting

around the edges of the frame

if we were to solve this

camera in another software

it might give you a picture like this to export

and essentially if we were to plug it into an ST

map afterwards

we can see that it's removing that

lens distortion

so it's basically doing exactly what we want

so that's kind of how these are useful

and if you start doing tracking other softwares

or you're getting potentially from another

match move artist or someone who did your track

they should be supplying you with something

for the lens distortion

that looks like this most likely

unless they can

export the actual numbers which is

another way to do it

but that's just to demonstrate how that's kind of used

and here's another way that's kind of interesting

we have a basic grid here and

basically all I've done is just taken

the same expression and kind of blurred it

but I blurred it through a noise pattern

so we're actually blurring the coordinate system

through a pattern

and if we look at the

ST map

we can actually see that we're getting this like crazy

weird effect

so that you could create some holographic effects or

you know other stuff like that

and you can blur and the X and

y differently and stuff like that

so you can come up with different

ways to use this

and if you guys have other creative ways by the way

I'd love to hear in the comments

I'm sure other people would as well so feel free

to post it there

but if we just check out the ST map

that's what we're getting

but if we do the same effect

without the ST map

we see that's giving a totally different result

because one is doing this to the image

and one is doing it to the coordinates of the image

so that's how to think of it basically

so the last way in the most useful way

this is

something that probably seniors can even benefit from

or intermediate composers I suppose but

this is really useful

and I use this on pretty much every CG

environment scene that I'm doing

because I like to work in a kind of Lightroom style

in terms of compositing like it's kind of

just like

doing my color grades and stuff like that in a

creative way

and so if we have

a basic CG scene like this

and you want to apply some color corrections to it

some secondary grading

if we just check out the camera move first

I'll just let it play here

we have this kind of establishing

sort of shot kind of a helicopter

flying over an environment type of shot

so it's a wide angle

and we can see

I'll just let it catch all the way through here

we have a scene like that

so if I were to

want to do a bit of secondary grading and

direct your eye in a certain direction

maybe there's some subject matter

such as maybe this is a character

walking up to an important object in our scene

and I want to end you know

basically like a concept artist

your eye is always going towards the

brightest thing in the scene

and maybe we want to just make this area a little bit

brighter

and maybe this area is a little bit less important

so we want to darken it

so you're not looking over in this

basically an empty area

and of course we can just do that with rotor shapes

but those rotor shapes need to stick to our scene

as the camera is flying through

like this and a normal way that

a lot of people are doing it and it's totally fine

for most instances is to use a card

card 3D

so you have a card and you put a rotor shape on it

and you plug that into a camera

and then you could kind of draw your shape

and it's going to stick

in the scene like that

but sometimes you want your

Alphas to actually

have the same perspective and actually stick to the CG

in whatever shape that it is

and that's why this is really useful

so if I just show you the problem here

if I go to the end of this comp

I've done some color corrections

so if I go before and after

a couple of these you see I've kind of brightened

this area a little bit

keyed out the highlights

and brought them up just a tiny bit

and then I've just darkened

and done some secondary grating

which is kind of creating a natural vignette effect

and is kind of drawing your eye in the direction of

the subject so we're looking in this direction

because we have a little bit more bounce light on that

hill and a little bit less light in this area

so that's fine that's all good but if we scrub through

we see that that's not working

and we can see that there's some weird

colors floating around

that's because our mats aren't tracked

so like for example this rotor shape

it's basically just not sticking

and that's not what we want

so we're going to go back to our technique and

create this expression

same thing but what you can do before hand

we're going to basically project this onto a 3D scene

so if I look at the 3d geometry

this is the same geometry

from that render

so we have the 2d render

and we also have the 3D scene itself

so if I kind of zoom out here

it's a little bit hard to tell

but this is the same

scene that we were just looking at

so we can see the spheres here

if I zoom down

we can see some spheres and all those little

objects that were sitting there

so this is the same scene as this

and

what we want to do is project this pattern onto that

scene and as we know this pattern stores the movement

of whatever it's doing

so if we project it

and stick it onto the scene

essentially we'll be able to just stick any rotorships

we want anywhere we want

and

have a lot of flexibility and speed which is the most

important thing

so essentially what I've done here is

create the expression

and we want to put a crop beforehand

and put the crop beyond the borders of the frame

and what this does is actually gives this

pattern a bit of overscan

and that's going to help

when we project it and you'll see why in just a second

I'll demonstrate

but we want that crop beforehand pulling out

and you see that dotted line

on the outside of the frame

if you hit

Q on your keyboard to make sure you have the overlay

another thing we want to do is make sure it has a solid

alpha because we're projecting it

it's important to have a solid alpha

so I've basically just create a shuffle node

and put the alpha to one by pressing that little white

button there

so now if we look at that in the 3D view

it's not the best representation but we can see

this pattern is sort of being projected

one other thing to note

is to make sure you guys have the crop off

for the Project 3D so

if I look through the renderview

and I hit tab we can see this is what this is doing

and if I just zoom back a couple frames

so I just kind of scrump back

we can see that pattern is

basically extended beyond

even what the camera was seeing on the frame

that projecting on

so we're projecting on frame 89

if I go back to frame 72 we'll see actually

beyond what that camera seeing

so one important box to check off is the crop

so if I turn that back on this is by default

so you see by default

from the frame 89 looks great

we're getting our pattern projected

but as soon as we zoom back

we can't have our rotor shapes going beyond

the edge of that

projection which is not what we want

we want to turn that off

and we also want to project only on the front of the

geometry

and the last thing

don't have any of these set because

you'll get some weird

kind of artifacts and stuff like that

so that's how I do it front turn off the crop

and make sure you have this crop

so we have that over scan you see if I disable this

actually you can't really tell visually but basically

the math is not the same exactly

so it's like stretching the pixels

versus having the detail outside of the frame

so just make sure you have that and this

and now that if we pre comp that out

we're basically done

so now we have this pattern

and I can scrub really fast

now we see that because this is pre comp

we can scrub really quickly and it's not using a 3D

it's not loading this whole 3D scene anymore

we've just created this 2d video

some of the render settings by the way

you want to make sure to render out 32 Bitfloat

and you also want to make sure

the compression is set to none

those two settings are really important

for the math because we're storing a position

and usually those kind of utility pass

especially this one you're going to want

the 32 bit and no compression

I've done a couple tests with this

and it is definitely necessary even to turn off the

zip compression

so if we check out our result here we have the image

if we want to just take a checkerboard picture and

just stick it in the scene

I'm just going to transform it down

put it in a random spot

and then plug it into the ST map

make sure we're set to RGB

and now if I hit play

you see that it's automatically tracking to our scene

and I don't have a large

projection setup anymore

I don't have to load and do all of this again

for every single projection I want to do

I can just put this stuff wherever I want

and it's going to stick

and wrap around our geometry and have the perspective

so as we hit play we can see it kind of wraps

so essentially we're gonna take the same principle

we already have that thing pre compt out

and we're just gonna apply it to a roto shape

so I have that

that image here and I have RCG scene

I have those same roto shapes that I've done

so for example I have this roto shape here

that brightens this area

it's a very subtle effect but it's

brightening this area

but just before

we use it in the mask of the grade

we're applying the

SD map which is going to apply that motion

to this alpha

so if I hit a

and I look at it

and I scrub through you'll see automatically

when it's not enabled

it's not doing anything and when I enable the SD map

it's sticking to the CG scene

and essentially also

one important thing that's kind of a gotcha

and you can mess it up

pretty easily because it's default

is you want to make sure to turn off

this

clip too you want to make sure it sets a no clip

and the reason for that is

the frame that we've drawn it on

so I drew it on frame 89

we can see I drew it a little bit outside of

the frame of the video

and if we have it set the format

we actually get some weird like stretching

but if I turn on no clip

it'll actually maintain what was outside of that area

so always make sure to do that with your roto shapes

if you're doing this

kind of tracking with these

EV coordinates

same thing with radio

so if you want to stick for example a radial

in the settings of the radio

you want to make sure it sets no clip

so if I look at that alpha

we can see all those rotors are sticking to the scene

I can look at this alpha

I used a radial up here to brighten

and you see that it's sticking to the scene

and that's essentially the idea

so that's a really useful way to use it

and it kind of opens up a more

creative way to just project a ton of different things

without having to

you know have a ton of

different projections

which is going to slow down your script

and that's all what

that's all it's about really

speed and efficiency and getting a good result

just one important thing I forgot to mention

is that there is

a little bit of limitation with this technique

and that if there's a lot of overlapping objects

you might have some kind of problems

so I've just done a quick roto shape here

along these two geometry

and I've kind of drawn a roto shape and I've used our

ST map you'll see that if I scrub through

it sticks and there's really no problem

in terms of this angle

but if I were to kind of expand

that rotor shape to the edge

of this tube so let me just double click this

and let's say I put it on the very edge

and just kind of put it like this

and it's on the inside

we can see it's inside that cylinder so it's fine

but if we scroll through

let me just make sure I have no keyframe

we scroll through

we see it's actually projecting through

our geometry and onto that ground that's behind

so it's not occluding itself

and the projectivity occlusion is not that great

so it's not going to be able to do that

so we might have to separate that

piece of geometry out or use an ID

to kind of remove it behind

so that's just something to keep in mind

if there's a lot of overlapping objects

this technique is not the greatest but

if it's just rocks and pebbles and stuff like that

for soft color grades this is still a very good method

so just something to keep in mind

so essentially that's the idea

if you guys liked the video hit like

I really appreciate it

and if you want to check out the other video

if you haven't seen it

I'll put it in the description below as well

and thanks so much