- [Narrator] The Scanline Render node, only uses
the 3D elements that are connected to it
to render a 2D image.
It's analogous to Renderman, Vray, or Mental Ray
from the 3D world.
Here we'll dive deep into the Scanline Render node
to understand it's capabilities in detail.
So heres my 3D scene.
Let me switch the viewer to 3D for you.
What we got goin is a camera projection on
these two cards from this image up here.
Actually a clip got a little animated sky
and background and lava flow stuff.
And you can see I got my little CG character walking along.
Okay now what we do is, I'm doing two renders.
First of all I am rendering the background plate by itself.
Now we have this contact print clip here for the feet
where they contact the ground, and I'm using
that with a grade node, simply puts some foot shadow
some contact shadows on the ground
which will walk with our character.
Over here, we're doing a fold up CG character render.
Which looks like this and then
that is simply composited over that prepped background.
So that's our test set up here.
Okay so let's take a look at the Scanline Render node
and it's participation in rendering CG objects.
Let's come over to the CG character part of this.
We're going to need a little more room here,
and we'll open up this Scanline Render node here.
Now this is for our CG character, and I'll hook
the viewer up to it so we don't see the background anymore.
The first item of interest her is the filter.
Let me push in on our character,
see this filter thing happening.
This is the filter that the renderer will use
to filter the texture maps and the other parts of the image.
This can have a profound effect.
If you wanted it to be sharper,
you might suggest the Sync4 filter.
If you really wanted it to be hideous
you could use the Impulse filter.
The point is that they all do have a effect
but you need to understand your filters
before you go messing with them.
I think we need another course on filters though.
Okay one of the main purposes of the Scanline Render node
is here on the Scanline Render tab is the antialiasing.
If we look at our CG character,
Everywhere you have the edge of the CGI you're going
to need antialiasing.
By default it's off for rapid rendering
but you need to select which level of antialiasing you need.
It's important that you choose carefully.
Antialiasing is very expensive.
If you crank it up higher than you need
You're wasting a heck of a lot of rendering time.
So just to show you this is what
the high antialiasing looks like.
And of course we saw medium and low
so you're getting more antialias pixels here.
One important thing to remember about antialiasing
it's not just the edges, interior fine detail like this.
Look what happens if I turn off the antialiasing, ugly.
And then we'll turn it back to medium, lovely.
So it isn't just edges okay?
That's the important point.
It's filtering all those pixels and that filter
is controlled by your choice of the filter.
We're going to circle back to the Z-blend options
in just a few minutes.
We're going to skip projection mode and tesselation cause
those are advanced concepts that you may not have
to worry about for years in your compositing career.
But let's talk about overscan.
Now overscan means it's going to render more of the image
than you're showing on the screen.
In fact the other one is actually better for seeing that.
So let's open up this Scanline Render node
and hook our viewer up to it.
So if I set the overscan to let's say 20,
that means I want to render 20 pixels outside of the viewport.
Now you're not seeing those.
Well that's because we have to tell
the viewer to show me the overscan.
So let's go to right mouse popup and say show overscan.
There we go, in fact let me make this even more obvious
let's set that to 50 pixels, this'll make it really clear.
So we're seeing our viewport right here,
but we're also seeing 50 pixels outside the viewport
and we can actually see the part of our camera projection
that is not in the viewport.
So what's overscan for?
Well there's a couple of applications.
Sometimes you'll be using in lens distortion operations
and there are some blurs that will look better
if you turn on overscan, so the blur routine
has got some pixels outside and they're not just black.
Okay so let's turn off the overscan
by setting that back to default.
Let's set our viewer back to please don't show me overscan.
And let's take a look at ambient.
We'll go back to our CG character for that one.
Okay, ambient.
Ambient means to throw a ambient light
on top of your character like this.
I don't know why you want to do that.
If it was particularly dark maybe you would like
to throw a tiny bit of ambient, and if you go crazy with
this thing you can actually give it a color.
But maybe we kind of don't want to do that.
So just in case you need to tap up, if you got pixels
are too black, okay?
You got too much black in your dark's.
You could tap up that ambient ever so slightly.
Okay let's circle back to this Z-blend stuff up here.
Now for that, I've got another little set up
for you to look at here.
This is a classic pan-n-tile setup.
Let me clear everything out of the property bin except
this Scanline Render node right here.
So here's what we got.
Let's say you got a pan-n-tile shot and the problem
is the intersection of the cards.
You see how the cards intersect like this?
Well what that means is, as you get closer and closer
to the intersection, it become ambiguous which card
the renderer should be looking at and if things are moving,
maybe you've got a moving picture back there,
maybe you've got a moving camera.
You're going to see pixel popping and you're also
might see a seam between the two cards.
Let's try and show you that.
Okay so let me come down here now see
this is our seam right here okay?
And oh, look at this, nasty nasty, doesn't quit line up.
So let's switch to the 2D view
right here in our Scanline Render node.
There's the scene, let's make it go away with Z-blend.
By default, it's turned off.
What it wants to do is to blend between those two cards
or any two pieces of geometry frankly.
Kind of blend back and forth and take the average.
Kind of like you ran a gentle blur,
so the renderer the renderer doesn't get confused.
The first thing you have to do, is tell it
what mode you want to use, then of course it's off.
You can go linear which looks like that, you see that?
Or you could go smooth which looks a little better,
I like smooth.
Next is the Z-blend range.
This means how many mythical units is
this range for the blending.
The reason there's a tremendous range on this
is because if the geometry is really small,
like this, these cards are only one unit,
you need a very small number.
But you might load in a CG scene from Maya or something
where the units are even 100s or even 1000s.
So for us, we want a very tiny little Z-blend range
like maybe there.
Look at that, look how pretty, it's all gone.
And just to show you, there's the before
and there's the after.
So select the mode you want and then set the Z-blend range
to get rid of those ugly seams.
In the next video, we'll see the importance of
the VG input to the Scanline Render node.