Original subtitles

Hello and welcome back

In this video we take a look at our final composite in fundamental

Perspective

It is typically the hardest compositing fundamental to follow because it can be very tricky to identify

That's wrong especially if you need a composite name

Where can I inform you here on exactly what you should be looking for when your matching perspective to sit you on the

So let's get star

Now prospective is all about how an object or element spatially sits within us

He needs optically make sense within its environment

Lot of the time and were talking about perspective it's affecting more complex shops where we are replacing a back

Entirely

Integrating CG

Shots of that nature

Another prospective of your footage is determined by three main factors and that is the focal length

The cameras sensor size and the positioning rotation of your camera if you have this

Information for all the elements in a short it will make matching your perspective significantly easier because you'll be

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Mathematically determine how to position yourself

Look at that later in this video

Do these three factors all have to do with perspective

Let's take a look at the two main characteristics that we need to match in order to have or correct perspective

The focal length and sensor size will give us or lens compression

And then the camera positioning and rotation will give us our vanishing

If we have these two characteristics match

We will have the correct prospect

Within our shop

So let's take a look at these two more in-depth and figure out exactly how we can find them

Lens compression is about how compressed elements appear within your shop

You can see in the skiff how focal length

Effects lens compression

Why do your focal length is the list compressed objects near you will appear

And then the longer that you're focal like this

Aka your lens be more telephoto

The more compressed your objects

Well why is this

What's take a look at an example in 3D

Here on the left we have two cubes been mugged at by a 20 mm camera

And on the right we have the same 2 cubes being looked at by a 200 mm

Why is the compression different

1 order to compensate for the increased focal

We had to significantly back or camera up in order to achieve the same relative Framing

What this means is that we have a significant disparity in the relative distances between or cubes

Camera

In a 20 mm example

A background cube is about 2.5 times further away than the foreground cube

Where in the 200 mm example

Background Cubism a d 1.2 1.15 times further away

NR4

And this large discrepancy in our distance is actually the reason that the objects appear more can't

The fog that self technically doesn't have anything to do with one compression

Rather the focal lengths forces you to move a certain distance away in order to properly photograph

Subject and the distance is what creates compression

So I guess you could say fog leave does cause lens compression but it only does so indirectly by forcing

Between you and your

What's prove this really quickly in this Nick script I have a 20mm conduit in a 200mm

These cameras are in the same position in are exactly the same except for the focal

Now if I wanted to have our 20mm render match or 200mm render

I need to scale up 10 times

You know this woman Transformers up that is exactly the same

That means that if we have footage that was shot on the exact same camera with different focal lengths

We can automatically know how much to scale a background in order to match or lens compression

The formula is to take your foreground focal line

And / your background focal length

And that will give you the amount you need to scale your background by

For example if we had an 80 mm foreground in a 40 mm background we would do 80 /

And that would give us a 2 time scale

My plug lead into a transformer

We would

Perfectly match Orleans compression

This is the ideal way to work and combine elements

Unfortunately it's not always that simple if you're using multiple cameras because that means you're also using

Portable sensor sizes

And like I said earlier or lens compression

Is caused by our focal length

And or sensor size again

Decompression is indirectly caused by these but it's caused by them none the less so what does the census

Let's have to do with this

What's a good look at this graph in front of us

The circle represents everything and lands could possibly see

The boxes within the lines represents the sensor size and what we can actually record

You're not the blue sensor size has a much larger field of view

Then I read sensor size

Despite having the exact same lens

So the field of view is the total amount of area that a camera can see it's surroundings

Based on the lens in sensor size

End goal for Ireland's compassion is to have the same field of view for both of our objects

It's a look at how that affects our formula when we have different sensor sizes on

You'll see that it's not as simple as just dividing or focal length are foreground by the focal length of a background

Now we need to find the percentage difference of a foreground sensor size compared to a background

And multiply or background focal length by

This may be a little confusing so let's take a look at an example say we have a 4 grand plate with 150mm

25mm horizontal sensor size

And then we have a 30mm background lens with a 20 mm horizontal sensor size

Once we pipe fell into a formula the result is we need to scale or background play Up by 4

I don't really expect people to have this memorise but I do write it down because even I occasionally forget

What word goes in

And if I have this info on the plates I'm using I definitely type it in because of the easiest start

White to get your perspective looking correct it automatically make sure your compression is career

The next characteristic we need to mash is our vanishing Point flash Horizon line

We need to be able to see the exact point where all of the angles in Arsene or converging

Because all of our elements will need to match these converging lines in point is determined by the

Tilt of our camera 1 footage was shot

Depending on your seen this may be difficult or very easy to determine

What's take a look at an image of an officer in walkthrough how exactly we can find the vanish

Image open in nuclear and that's where and how we can find our vanished

Really quick

I'm just going to put those two are GBX I want to actually draw some bits for wind

And to do that we need to use the open spline

And now that we can do is we're going to find the lines that we believe in real life are parallel with one another

I'm going to start here and roll one very more online

I need to make sure that it lines up all the way

And this is a little tricky to do is just one of you were and so we can actually make bots for the risen

And we can do that by hitting the strap down kind of windows and typing in

New comp viewer

Then we can go ahead and drag it to the right over here and split or view

So this is a little bit easier to adjust

You can see we have our second even out here and you can see what it is connected to

I'm going to zoom in here

Just turn off this right of shape so that we don't see it cover image

Change the width of our stroke to 2

And on this for you I'm just going to drag or end point here

Until we are all the way around

Down

You want to get there

Right on the money here

I'll wait till that is our first mine

I know what I want to do is I'm just going to duplicate this

What's go ahead and find another line

This task here

Now I'm going to you again break this wine until it's

In line with third desk entirely

Resume and we can make this nice and precise

Something like that alright

Starting to get a rough approximation of where are vanishing

Is going to do three or four of these

Duplicated again and

To see if this works and put it right at our current intersection point and move this

Here

Closely

Let's see how well this Lines

Tiny little adjustments italics actually the same that's alright because there is one distortion

Is a few facts

Go ahead and

Grab a

Point

This again

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Is that in line

Megane what does going to Linus tapas bar

A little bit

Great so you can see we have some consistency

And we're all of our lines are going approximately going

Yeah I can see that

Prudential e a l let's see it

It does mean or vanishing point is approximately

What does that mean

Well we can draw line where these are in the setting I'm going to go right here it seems to be in the middle

And what we can do now is we can click and drag this line and any other

Horizontal lines that go to the standing shin point or going to line up we can see it's in line

With this table

With the boys on a swallow with the TV as we move this around

If this is a lining up with your services

That means you have a pretty accurate vanishing

And this is exactly what we were

Great

Now there are two directions that this is currently receding

You're going to want to follow this process again except for the right side this time

Go ahead

Make another landline

Human hair so I can see what's going on

Who

Now we can grab this portion

Scan

Over

It's a little bit tedious but this process is 100% worth it

Can I help you align your seen so much

It's worth the five to 10 minutes

Text to set it up properly

Call so we have that approximate intersection what's good for the ceiling now

Peter Sagan

Here

And let's see how we can get this July

Up

Lower

Even a little lower

Literally finicky here now

This is actually an excellent vanishing Point Deezer all lining up songs go ahead and just test that

We will duplicate this

How much has Tesla ever seen that lines up that lines up

Checking period that lines up

So excellent

Very good very

What's that extra 1

In turn this Rolo shape on

And now we can see all the vanishing

Wine that we've made

Let's go ahead and check or background play because this isn't the original we had in there and see her purpose

Is stacking up

We can go ahead and duplicate one of these again

And we can chat

Best perspective

Lock screen last year

And you can see

The lines are not

Lining up

A man is not what we want

Because assuming that this is built like a grid

This should be square and flush with our building your

So that is not correct

We can also check out our other lines right here

Just going to

Grab the sand move around

These ones actually

Too bad this is kind of lucky that

This is winding up as well as it is

But the issue remains that not over vanishing lines are in line with one another

So this doesn't quite feel

Correct

And so I've actually drawn finishing lines already

For this background

You can see it lines up we just had the exact same process that we did

And

Are foreground image all of these are lined up

We have our two distinct vanishing points

And so now what we need to do is line or pairs of vanishing points up with one hand

Arbroath shape here

And what I'm going to do is just roughly drawabox

Where are the centre of our vanishing lines are

And I'm going to select or background please

And move our anchor

Into the vanishing point

And let's

Go ahead and move this right

On top of

Let's see what this has done for us with another perspective check

You can check some lines and here now

And now we can see

This is nice and mine that anywhere that we check it

Which is excellent this is exactly what we want

And we can go ahead and see if this is working for our other line

McGregor vs here

Start investigating

A little bit

How to tell exactly

What is

Here but you can see there's a little bit of a discrepancy here

This is why scaling by eyes so difficult

When your trying to align your backgrounds

It doesn't quite a line with her other finishing

Weekend again

Follow the exact same process

Weekend

Look at the vanishing lights here in a cycle

We need to scale this app to measure of location

What's go ahead and start scalene and we can rotate

Are vanishing point a little bit

And now they're right on top of you

So let's take a look

The Snail

And let's check all of our lines again

So now that's very accurate

Horizontal building is accurate

Everywhere that we check

Perfectly aligns with a reindeer

So now if I turn the stereo off

And I just look at

Final result only get rid of that second viewer

All right so this is probably at there still one more issue

Because we have are receding Lines

All nice and mind

We still have our vertical lines you can see here

Tilting out words and this doesn't quite line-up

With are edges here they should be perfectly

Vertical along with our sins

There will be a little bit of bowing of the lens that takes place

So what do I do to fix that

Is I make a corner pin

And what I'll do is I'll turn it off

And let's move

These points into the corner of our window

Just like this

And then I will copy the two points just a snapper from there

And now I turn this on is going to be no effect on her image

Which is exactly what

So now I just want to skip these to the left or to the right to a line or verticals so I'm going to grab

Q4

And just screwed it to the right

A little bit

I'm here

Mrs make sure our verticals are nice and consistent this entire time

Looking at the stash line

Like a slave gone a little too far

Just like that then on a right side here

Chequer building

Using a corner train because it's not consistent throughout the entire frame

So grab r23

And to the left a little bit

That's nice and lined up

And Derry girl let's go ahead and turn it off and on

The Adjustment is saddle

Stacks of subtle differences make a huge impact on the final

That's got a head and full screen SSE

This is very words

Dropping the image in

And this is with our perspective aligned

Now off about this may not have not too bad but clearly when your ab with our align perspective

This fits with an art scene

Much much better

Van Basten

The perspective is all about the subtleties and getting them to align

And we've not only allander vanishing points but we've actually also fixed or compression by her

Windows on top of each other

So this is a great technique to use when you don't have

That information to do the mathematical School

What happens if you don't have such a friendly shark

What if you are able to determine

Any van

Well the first thing you need to do is try to establish your camera

Your camera height is where receding angles will become perfectly flat as you can see in this image here

Any angles that are above or below the camera will have a more and more pronounced v-shape

A receipt

If you can identify and then align your camera height between your two pieces of footage

You're off to a great start

Then you need to look at available visual Cues that inform you about your lens compression

Is images undergo more lens compression the receding angles become flatter

Where in wiper images

We can see the receding angles become significantly more pronounced and again the culprit behind this

Difference in the intensity of a receding angles is all about the relative distance to the cam

Veneer corner of a stack of boxes in the 50mm lens

Is a decent about closer to the camera

My other two corners

Put on the 150 mm lens the relative distance between them is negligible

And that's why they appear much

Weather in closely packed together

Do you need to take all the visual Cues that you can determine how compress the images and do your best to ski

Your background recording

It can be very difficult to scale correctly we do have an advantage if we don't have many visual Cues to a

Also means there are many visual Cues for the viewers to tell it is off as well

So it's a little more forgiving but still important to try to get it as accurate as we can

And that wraps up our final compositing fundamental

That is prospective it is definitely by far in my opinion the hardest to read

Turn up an eye for

It took me several years of doing incorrectly before I was able to see it immediately

And so don't get discouraged if you're having a hard time with that it's one of those things that is little more

And will come with experience

Don't get discouraged and thank you very much for listening

And I'll catch you in the next one