- [Instructor] Camera projection is a fundamental technique
in visual effects.
So it's important to learn how to set it up.
The whole idea is to take a photograph and project
it on to matching geometry with a 3D camera.
Then rephotograph it with a second camera.
So I'll show you how to set up a camera projection.
These two spheres simply have the images texture mapped on
them in the regular way.
We have a scene camera here that we can look through
to see our results.
Or go back to the default view.
So to set up a camera projection I'll set up the read node,
come over to the 3D pop up shader, project 3D.
The camera projection node is a shader.
So we'll select that, and hook up our projection camera.
Let's scoot in a little closer here so we can see
what's going on.
So the projection camera is like holding a slide projector
in your hand and then shining the image on a sphere.
So let's look at the project 3D property panel.
Not much here, we have the projection on both,
which would be the front and the back,
or you can say just the front,
or you can select just the back.
Normally you're going to do it on the front or both.
Now if we look at our projection camera,
I'll open up its property panel so you can see if I shift
my projection camera left to right obviously the
projection will shift with it.
You can also go to the projection tab of your projection
camera, and adjust the focal length,
changing the size of the projection on the geometry.
I'll reset that back to default.
Also we can hide our projection camera by setting
its display to off and then we won't
see it in the 3D previews.
Now let's take a look at our scene through our
scene camera, lock the view finder and play.
And I'm going to ping pong that,
and now here's the 2D render of the same scene.
So the camera projection can be rephotographed by
another camera.
And that's the whole principle of the thing.
So let's take a look at an actual work flow example.
We'll stop this, I'm going to slide over to here,
and hook up my viewer.
We'll select the entire backdrop node and type D
to enable all the nodes together.
We'll start by looking at the original photograph.
Again camera projection starts with a picture.
Here's a photograph of a box.
Keep in mind the key point is it already has all
the lighting and the shading and everything built into it.
So our task is to set up a matching camera in geometry
to project this image onto the geometry.
So if we select the scene node here we can see our
basic setup, our projection camera,
I'll turn on the display for that.
So you can see how the projection camera is doing.
So the projection camera is very carefully aimed
on a piece of matching geometry.
If I move the projection camera even the tiniest amount
the projection breaks down.
So you have to be very accurate in the position
of the camera and the geometry.
And sometimes this is a non trivial task.
Okay I am going to hide my projection camera
so we don't see it, hook up the viewer to the
scan line render node.
Now our scene camera has a nice camera move in it.
If we look through the view finder of the scene camera
we can see that this is what our scene camera
is going to rephotograph.
The static photograph projected on to the geometry
is being rephotographed by a moving camera.
We switched the 2D view and play,
we can see what the final render through that
scene camera looks like.
And to make the scene a little more interesting
we can add a little bit of geometry to the picture.
The brilliant thing about camera projection
is that it's photo realistic because you start with a photo.
It has all the texture, lighting, and shading built in
which would be very time time consuming to duplicate
using all 3D modeling texturing and lighting techniques.