All language subtitles for 2月21日 (8)

welcome to this overview of PXF Vector Etchblur

so here I have a clip of someone playing basketball

and I want to

cut the player out and replace the background

with a roto

so so I have a roto prepared here

I'm using the copy node to combine the RGB

and the Alpha together

and I'm using the premolt node to have an RGBA

premultiplied image that's ready to be put on

top of a background using n over

so far so good

so that's great

however there's a problem

if I look at the footage it's got motion blur and my

Roto does not have motion blur

so if I look at the basketball

the inside is blurry and the edge is sharp

that's a problem

so typically we would turn on the motion blur

in the Roto node

so if we go back in the Roto node

we can turn on Global Motion Blur

and now I have

a blurry

alpha so my alpha has motion blur so that's great

but there's a problem when I combine the blurry

alpha with the blurry picture

I can see in my result here parts of the ground

showing through the edge

and that's normal

see

you can see the lines from the basketball court here

so that's normal

that's expected

because when you turn on

the motion blur

the alpha

grows and we end up with parts of the background

so a mistake would be to try to fix this

by shrinking

the roto making the shape of the ball smaller

so that the blurry areas stay on the opaque bits

this will

of course fix my issue of seeing the ground but

my ball will end up looking smaller than it should

so that's a problem

the reason we're having the problem is because

in the this image here

in the blurry parts we're having a mix of the ground

and the ball

and we just want the ball we don't want the ground

so we're stuck here

we can just use the motion blur on the roto side

we need to apply motion blur here after

the premultiplication and that's where PXF Vector

Edge Blur comes in

so let's copy our branch here to compare

I'm gonna turn off the motion blur in the roto

and we're gonna bring in a PXF Vector Edge blur

and I'm gonna connect it here

and we can compare

we don't have the same shutter speed

so I'm gonna slow down the shutter here

here we go

so now we should be able to compare apples to apples

so now this is the version with

Vector Edge and this is the version without

so you can see there's quite a difference

between the two

let's comp it on top of our background

here we go

so this is the old way using the motion blur from

Nux Roto

and this is the new way using vector edge blur

so what's happening here

basically what we're doing is now we're

turning off the motion

blur in the Roto

and doing only the opaque areas in the alpha

so the Alpha or Doroto has been

made as tight as possible to include only

the opaque bits and not

to include the motion blur

once we have that

we're using a vector generator

under the hood to analyze the motion

and a vector blur to basically blur the edges

so not only are we blurring our alpha channel

we're also blurring

RGB values so essentially we're taking

the opaque bits of the ball

to recreate the transparent bits

which we cannot use from the

footage because it's mixed

with the ground

so this is giving us a pretty good result

so let's look at the

knobs and settings in Vector etular

so the first one here is

which channel to analyze for motion so basically

where are the motion vectors coming from

are we analyzing the motion of the alpha only

or the RGB it's up to you

usually alpha gives better result

but you can also analyze the motion

of the RGB image

so that's your first option

second option is whether or not to apply

the blur only on the edges

so if you turn that off you can blur the inside

this would be a mistake here

because now we're applying motion blur

to pixels that already have motion blur from the

footage so we don't want double blur here

but if you wanted to you can turn that off

you can choose which method to apply motion blur so the

Vector Blur 2 method is using the GPU

accelerated recent

Vector Blur node

this one uses the old node so it might be

useful if you're having bugs or

if you want slightly different results

this is the old Vector Blur node

and you can use the Nuke Motion Blur node

which uses multi sampling here

so you can adjust a number of samples

so if you have two low samples you're gonna see

doubled up edges here

so make sure to adjust that

if you're using the vector blur method this doesn't

make any difference

shutter time is how

slow or fast your shutter is

so the smaller the value this

less blur you're gonna have

so if you set it 2.5

this is equals to

180 degree shutter angle this is a 360 degree

shutter angle and this is would be a

90 degree shutter angle

the adjust B box

feature is

to fix errors on the edges of the bounding box

so let's create a bounding box here

I have a bounding box on my roto

so we're gonna use the copy B box

feature

and we're gonna copy the bounding box from our roto

to our pre multiplied image here

so now we have a tight bounding box around our

basketball player and if we

use our vector edge if we don't

grow the bounding box

you might have these kinds of artifacts

streaks on the edges

this seems to be an artifact of the vector blur node

so we need to grow our bounding box a little bit

we have the option here

so for example here I'm adding 50 pixels of

extra size to my bounding box to

get rid of the artifacts

so this is there for those types of problems

lastly we have to mix slider

just like most nuke nodes we can mix

our effect with the original

so that way we can blend between the original and

final effect so there you go

that was an overview of PXF Vector Edge Blur

I hope you've enjoyed it and I'll see you in the next

video goodbye