Camera Projection

Camera Projection

Camera projection (or camera mapping) typically begins with
a still photo, which is then projected onto 3D objects that
match the dimensions and placement of objects in the
photo. You can then move the 3D camera—typically only
along the Z axis—providing the illusion that the photo
is fully dimensional (right up until things start to tear
and break as areas and perspectives that aren’t there are
revealed).
Figure 9.18 shows a camera projection that ambitiously
features two military vehicles parked in the foreground.
A dozen separate white solids with masks were created
to form a crude 3D model, ready to receive a projected
image. This example shows both the magic
of this technique—deriving perspective shifts from a fl at,
still image—and the associated problems of image tearing
when an area of the frame is revealed that had previously
been obscured in the source photo.
The setup is key: How is it that the one “texture” (the
photo) sticks to the 3D objects? The fundamental concept
is actually relatively simple; it’s a virtual version of a slide
projector and a bunch of angled screens. Getting the setup
right is a question of managing details, and that part is
fairly advanced and not for the faint of heart (which is why
mention of a third-party option follows this description).
The steps to projecting any still image into 3D space (an
example of which, 09_cameraProjection.aep, can be found
on this book’s disc) are as follows:
1. Begin with an image that can be modeled as a series of
planes.
2. Create a white solid for each dimensional plane in
the image. Enable 3D for each, and under Material

3. Add a camera named Projection Cam; if you know the
Angle of View of your source image, add that value.
4. Add a Point light called Projector Light. Set its position
to that of Projection Cam, then parent it to Projection
Cam. Set Casts Shadows to On.
5. Duplicate the source image, naming this layer Slide.
Enable 3D, and in Material Options, change Casts
Shadows to Only and Light Transmission to 100%.
6. Slide not located properly? Add a null object called
Slide Repo; set its position to that of Projection Cam,
and parent it to Projection Cam. Now parent Slide to
it, and adjust its scale downward until the image is cast
onto the white planes, as if projected.
7. Now comes the challenge: masking, scaling, and repositioning
those white solids to build the model, ground
plane, and horizon onto which the slide is projected.
Toggle on the reference layer and build your model to
match that, checking it with the slide every so often.
8. If planes that you know to be at perpendicular 90
degree angles don’t line up, you need to adjust the
Zoom value of the Projection Cam, scaling the model
and slide as needed to match the new Zoom value.
The example fi le includes an expression applied to the
Scale value of the Slide layer so that the slide scales up
or down to match however you adjust the Zoom of the
camera, which is not necessary but is helpful.

9. Once everything is lined up, duplicate Projection Cam,
and rename the duplicate (the one on the higher layer)
Anim Cam. Freely move this camera to take advantage
of the new dimensional reality of the scene.
10. To get everything looking sharp, go to Composition
Settings > Advanced > and click Options; boost the
Shadow Map Resolution from its default Comp Size to
a higher number as needed (check the image at Full
resolution to see if it becomes sharper). I tend to max
out this setting and take the render hit.
The best way to learn about this is probably to study the
example fi le included on this book’s disc.