All language subtitles for Nuke Compositing for 3D Artists week 2 - Classroom - CG Master Academy_4

in this lecture

we're going to use the tracker um

and the tracking data that we solved for earlier

to do a match move and actually track another image

another still image to this

landscape footage that we have

um so the plan is to take this image

um and use the sky from this image to uh

put in place of the sky that we had in our other um

landscape footage

so the first thing we wanna do

um obviously if you have a close look

this landscape footage of ours is in HD

so it's 1920 by 1080

and this other image

the still image is a 4K image

so first thing we wanna do is reform at this image

so it's in the same aspect ratio

so we don't have any issues down the line with our

aspect ratio

so what I'll do is 1

I'm going to put a shuffle node down and set our

alpha to solid white

and essentially give our image an alpha channel

so we'll set this to one

so now we have an alpha channel

and then what we're gonna do is grab a reformat node

and have this image reformat to our HD image

so now we're in the same aspect ratio

so everything should play nice from here

um so what we're gonna do is just do a really simple um

mask for the sky here so we don't

we don't need all the horizon and foreground areas

from this image

so what we could do is simply grab a um

we could grab a oops

we could grab a ramp

and what we could do is move this um

and move this ramp up like so make sure it's straight

and we'll use this as our alpha

for this image right here

and what we'll do is we could multiply this against the

our image so we'll go

be input being our image and the

ramp being our alpha right there

and we could always adjust this ramp

just so we could have a little bit more fall off

if we wanted

move this up just so there's a little bit more trans

little bit more transition in that image

now what we'll do is

if we just do a straight merge and put this

over our landscape image

that's pretty cool

um obviously we need to get into doing um

roto or some kind of luma key to isolate

our foreground plant and also our mountain ranges

but for right now we're not gonna get into that

we're just gonna

have a quick look at what this image does

um and what I could do is

kind of lure this a little bit more

make sure it's straight

and move this fall off in a little bit

so right now

if I press play

you could see our sky is not doing anything

because it's a single image

our plate underneath is moving

but our clouds

aren't moving with it

so in order to get our

clouds to move with this footage underneath

we need to use this tracking information

and have it match move with our plate

so what we're gonna do is we're gonna grab our tracker

one that we saw for earlier

and plug this into

the input of our image

we wanna apply the match move to

and then under this transform tab will set

the transform type to match move

and the other thing you wanna do is

this track reference frame

you wanna set this to the frame

you're using to line up your image

so right now we're on frame 1

so that should be fine

so we'll say set to current frame

and then if we connect

the tracker

to our to our image and we view our overnote

and now if we press play

look at that

we've got our clouds moving with our footage

and that's doing a pretty good job sticking to it um

now if you have a look you could see that

we're getting cropped right here and at the top

and the reason is this first frame our image

lines up pretty well

but if you look at the bounding box of our image

it's really just it it this is the resolution for it

so we're cut off here and we're cut off at the top

so once this track starts to move

there's really no more image on the left for it

and as we get a little bit further in the timeline

you could see we don't have as much image

at the top either

so we could solve for that

we could solve for that by simply just

scaling up this image a little bit

and what we could do is just scale this

maybe 30% or 40% just to make sure

look at our last frame

and now we're pretty good

that might be a little bit too much of a push in

so we could just

yeah maybe about

1.3 30% pushing

and now if we kind of scrub through here

you could see we have enough image to cover

um and if you notice these

these red red outline around our nodes right here

as well as the um

dotted black hash lines around it

that is letting us know

it's a new feature in nuke that our bounding box is big

so it's essentially it's a visual warning that hey

keep an keep in mind

your bounding box is getting too big

so this might slow down your

your process and your new script

so it's pretty handy

really simple way to resolve this is if we

put another reformat after the fact

and you could see that

eliminated the red box around this

it's essentially

will no longer have a large bounding box

happening over here

um if you don't wanna use a reformat

you see that came back

you could also use a crop node

and that does the same thing

it basically just cuts

anything outside of our aspect ratio of 1920 by 1080

so either way you could use a reformat oracrop

but now if we look at our merge

and we press play

we've got our sky tracking quite nicely to our

to our landscape footage

and if we wanna kinda have a closer look at that

we could bring the opacity down on this

something like that just to make sure things are moving

and you could see our cloud cloud edge right here again

sir mountains back here

same with the mount the foreground bush and the clouds

and the other image over here are moving pretty nicely

and relative to what the plate is doing

so that's great

if one other thing to point out in our tracker

if say let's go to frame 60

and if we had use frame 60 to line up with our

image right here

so for example

what we'll do is we'll take

I'm gonna bypass this tracker

we'll just go straight multiply node over our image

and let's say we'll do another transform here

and let's say we had lined up this image

specifically on this frame

so let's let's move this up a little bit

let's move it a little bit to the to the left

and let's push it push in on this a little bit too

we'll go to 1.3 as well again

so if we had used frame 60 to line up our image

what you would want to do on your tracker node

what you wanna do on the tracker point

set this reference frame to be frame 60

so this will zero out or translate

so that frame 60

if I disable this lines up exactly to what we had done

and then from here on out

if we press play

it's going to

apply the same motion to it

so that's something to always keep in mind is

if you're getting a matte painting

or if you've done Broto

that you wanna track to your image

always set this reference frame and the tracker

to the frame that image is coming in on

or what the image you

what frame you used to line it up on

so if a digital matte painter had given you a

sky with more hills and what have you

painted on here

and they used Frame 60 as their reference frame

and not frame one

you need to make sure you always set that same frame

in the tracker

so that it lines up on that initial lineup frame

and the rest of it can just match match

move and track along with it um

the last thing to point out with the track node is um

if you don't wanna directly connect this as well

there is another option um

if I detach this real quick

if we go back to our tracker tab

there's this export option here

and you have the option of exporting

corner pins with the

current frame

or you could use the

transform reference frame

or you could bake out all the key frames

um as well as you could do the match

move or stabilization

um etc here

so if you don't necessarily wanna use this tracker note

and you wanna

keep this kind of

um you know

detached and off screen

you just want to use the tracking data from it

what we could do

is in the export tab

we could select

we want to select them

transform match

moved and we could bake out the keyframes

if we don't bake it out

so if I select this

transform match

move and I hit create

you'll see an expression link

with this track

tracker node

I'm sorry this transform node

with these values

linked to the tracker

so if we look into this transform tab

you could see this translate values are the same

as what our tracker showing

same with the center frame

so that's what the Transform

Export looks like

the other option is you could bake out the key frame

so you don't have this link set

so here we could go to Transform

Match Move Baked

and if we hit create

now we have

now we have these key frames baked in within this node

and it's no longer dependent on what this tracker is

so there's pros and cons to each um if

if for some reason

the nice thing about having the

the link is if we changed our reference frame on this

on the reference frame of the tracker so we

will set this to frame 10 and set to current frame

you'll see our tracker zero out

so it's gonna always link to what this tracker has done

whereas if we've baked the key frames out

it no longer changes and updates to it

so that's the difference between um

exporting out transform match move baked

or just transform match move would

will keep the links allowed

uh keep the links to it

so it's completely up to the user at that point

how you wanna use it but um

in this case

now we could use this um

baked out transform

and we'll make sure to crop this as well

so our bounding boxes and get any bigger

so now we could press play

and we got our trackers or we got our transform

doing the match move based on this tracker

without us actually using this tracker in our stream