All language subtitles for 04_Filter_flare_ghosts,bright_inner-lens_reflections

in this lesson

we're gonna learn how to add in ghosts

often caused by filter flare into our comp

so here's where we left off

we added a vignette

and in between each lesson

I'm gonna go in and write a little bit about

the optical

aberration and the problems that are happening

and the way we added it in

so now let's take a look at filters

and filters are very common inside of shooting video

because we need to shoot at a

consistent frame rate

and so if it's too bright or if

uh many different things are happening

we're gonna need to add

one or many filters on the end of our camera

now this is what a filter looks like

and the problem occurs

because filters are flat

and so what happens is that they have a

very high likelihood of reflecting

bright lights back into our camera

now what is this look like

well I've got a quick video here where we can see

we have these very bright lights here

and you'll notice as I frame through this

they are creating ghosts that move throughout the frame

depending on where they are in space

as well as how the camera is moving

now filter flare ghosts are dependent on the

camera lens

as well as the focal length or

the zoom level of the lens

so depending on that

these can change

they can either get smaller or get larger

now you'll notice that they move exactly opposite

of the bright lights in uh

almost an exact opposite arc or a rotation

180 degrees

so you'll see these mostly or

almost always whenever there is a light

that is incredibly bright inside of the scene

so let's go over here

and let's take a look at what we have

and we do not have many

very bright lights inside of our shot

however if we turn on our zebra stripes

we do have some areas that are ultra white

so these areas will create a filter flare

so let's begin

uh by dropping in a transformation to rotate

our entire frame

so hit t and connect this in

so here we have a transformation

and let's rotate this 180 degrees

so we're just gonna flip

the image around its axis

and now we have this flipped around

now we do not really wanna use the entire image

we just wanna use the ultra bright areas

so for this

let's key everything else out

so I'm just gonna hit tab

drop in a key or node

and I'm just gonna increase this up to one

and so now inside of our alpha channel

if we hit a

we can see that only the ultra bright areas are

staying inside of our frame

so let's pre multiply this

so we remove the rest of this information

and now we only have the

RGB information of our ultra brights

so now we need to add this back

into our original frame

so I'm gonna move this over here

and just for cleanliness sake

I'm gonna create a new dot

and then let's drop in a new merge note

so I'm gonna hit the m key

connect this to our original

and connect the a pipe into our premult

and now we can see

we have the beginning of this filter flare effect

now if we take a look at this footage

you'll notice that it is

not anywhere as bright as the filter

or as bright as the original

that we have here

this is because again

a lot of energy is lost

and not a lot of energy is reflected

so what we get is a very soft

you'll notice it is blurred

compared to the original light source and much

much dimmer okay

oops excuse me

if we jump back to nuke

we can add a blur

and then turn down the mix

so I'm gonna pull my merge down a little bit

blur this after our premult

and let's just give this

a little bit of a blur

ah maybe something like 7.5

and in our merge

let's pull our mix down quite a lot

because again

this is not

going to be

uh a purposeful reflection

it is just an

artifact from the lens that we're using

so here we can see

we have our

basic filter flare added in

so this is going to move nicely around our shot

and this might

even be a little bit too strong

we can pull us even

further down

again this isn't something you

really want to see or you

it's not something you want your

eyes to be drawn to

this is just another

important consideration that tells

our eyes that this is being shot through a real lens

with a real filter

and what I really like about filter

filter flare reflection

is that it has an interesting movement

you'll notice

the movement of this

is opposite

of the movement of our frame

and I find that that gives it again

a much more life like quality

by having our

reflections or

our hotspots

be moving one way

and then having this filter reflection another way

you can see this

adds quite a bit to

the realism

even though this is

an incredibly

simple effect

you'll notice that this

now looks like it's being shot through

some kind of glass

because whenever we

add a flat piece of glass

or a flat piece of material

over our lens

it is going to create these kind of hot spots

so we just play through that

once can see here we have that nice reflection effect

now again this is dependent on your focal length

so you can try shooting with this

or you can just eye in the

effect however you like

now a common thing that will happen with this filter

flare is it will be scaled differently

so currently we only have 180 degree rotation

and this is a sort of a rare circumstance

now you'll notice inside of this movie

we have 180 degree rotation and not much else

however for certain zoom lenses or certain lenses

will either scale up the reflection

so we could just scale this in our transform

or it will actually scale it down

so depending on the look you're going for

uh go ahead and just play around with different scale

values for this uh reflection because

it is going to slightly change how your

effect comes out

and again try different blur settings

and different mix settings to see what you like

now there actually is another way to add this in

uh one which I didn't really find too much

uh evidence for online

but I've seen many times before

so to see this

uh kind of secondary filter flare

let's copy and paste this

and this is an alternative actually introduced by

Ed Wetstone

one of our creative development authors

who has some great compositing tutorials

and instead of a normal blur

he actually uses a radio blur

so let's go into our blur here

and instead let's uh drop in

uh a directional blur

which is where the uh radio blur lives

and change our blur type to radio

and what this is going to do is it's going to smear

our hotspots around in sort of a circular fashion

again we can come in and change the blur length

and make sure your blur

center is in the center of your frame

I'll see here

we don't have a set to default

so my frame is 2 80

and the center will be divided by two

and 7 20 / 2

and that will give us the correct blur center

now if you're gonna have multiple filter reflections

I would use different scales on each of them

so that they have a kind of different characteristics

and we can see on the second merge

uh it's gonna be a very subtle effect depending on how

long we set this blur scale to

we can see that right there

and again this is um

an effect that happens because of filter reflections uh

so you can add this in if you wish uh

it just gives it another layer of that kind of

uh reflections happening from the glass

you can see here we have kind of this

smeared secondary filter reflection

okay great so that is how we can add in

filter flare reflections

so it's a very simple process

we just take our original image

we flip it upside down

or 180 degrees rotated

and then we can scale it if we want

from there we key out everything that is darker than

very bright white

now this in in this case we have an EXR image

so we have color values over 1

as you can see here

we have some values in the threes

in the fours

in the fives

and so this will work

if you're using a traditional piece of footage

something shot with a camcorder

a real camera

or a piece of film

you might need to drag this back a little bit

just so you pick up some of those

non HDR values

but since we have an EXR

we're gonna have values in the ultra white range

from there you can just pre multiply

all the other color values away

blur it a little bit

and then merge it over the original footage

at a very low mix value

and that will give us these very nice filter flare

reflections that act and

move differently than the rest of the frame again

giving us the effect or giving us the illusion that we

are seeing this

through some sort of glass mechanism

so now that we have that done

let's take a look at

lens distortion and field curvature in the next lesson