Double click on your 3D object file. [A future online version of this
tutorial will include an object file, "00_detailed_lamp_v_009.car," to
use while following this tutorial online.] When Carrara 4 asks you for
the background file, point it to your background file. This file opens
in the Assembly Room. Go to the Properties Tray on the right side of
your screen and select 01 Base Pass in the Instances Tab in the lower
half of the Tray. Then click on the Film Strip icon in the upper right
hand corner of your screen; this will take you to the Render Room.

Click on the Rendering Tab in the Properties Tray. Make sure that the
boxes next to Shadows, Reflections and Bumps are checked. Then click on
the Render button in the bottom tray. Save the file as
"01_base_v_001.jpg" to a working folder. This will render out the base
color and highlights of the lamp in one pass.

Click on the Hand icon in the upper right hand corner of the screen,
which will bring you back to the Assembly Room. Uncheck the Visible box
in the General Tab, and the Show Object in 3D View in the View Tab of
the Properties Tray. Click on the Fire Pass in the Instances Tab. Go
back to the General Tab in the Properties Tray and check Visible, then
check Show Object in 3D view in the View Tab. Click on the Fire-fire
layer under the 02 Fire Pass and once again check the visible box.
(Note: 02 Fire Pass layer is the only layer in this tutorial to have
sub-layers.) Now go back to the Render Room and render and save the
image as "02_fire_v_001.jpg."

Back in the Assembly Room repeat steps 2 and 3 for the 03 Light Pass,
04 Reflection Pass, 05 Alpha Pass, and 06 Alpha Lens Pass. Name the
files in the same manner so that you’ll be able to find them easily in
the next steps. Note: We are rendering a separate alpha pass for the
lens because this will let us position the lamp freely when compositing.

Launch After Effects and open your AE file. Click on the Light Assembly
Tab to make it active. Drag your base comp from the Project Window in
the upper left corner of your screen to the After Effects timeline. Set
the layer mode to Normal. Next, bring your fire comp
to the timeline, drop it on top of the previous layer and set its layer
mode to Add. Similarly, drag your reflection comp to
the timeline, drop it on top of the other layers and set its layer mode
to Screen.
Then click on the little triangle and lower the opacity of the layer to
25 percent. Drag your alpha comp to the top of the layers in the
timeline and set its layer mode to Stencil Luma.
This mode allows you to use a black-and-white image in the color
channel as an alpha channel.

Click on the Top Level Assembly tab in the Composition window to make
it active. Then drag your background comp to the timeline, setting its
mode to Normal. Drag your light comp to the top of
the layers and set its layer mode to Add. Drag your
reflections comp from the project window to the top of the layers in
the timeline. Change its layer mode to Add and click
on the triangle to lower its opacity to the level that you think looks
realistic.

Next, we will duplicate the background layer to let us fake
transparency of the glass lens on the lamp. Click on the background
layer to select it. Go up to the Edit menu and select Duplicate from
the pull-down. Place this duplicate layer on top of all the layers in
the timeline (yes, it will cover everything, don’t worry). Drag the
Alpha Lens comp to the top of the layers and leave its layer mode in
the default Normal mode.

Make the background layer active by clicking on it and then change the
Track Matte of this layer to Luma Matte and change
the layer mode to Add. Lower the opacity of this
layer to make the reflection and lens glass look real. It should be
around 10 percent.

Go up to the Menu and create a new layer by clicking on
Layer>New>Null Object. Click on the triangle to
Scale this object to 2000 percent which will put the
bounding box outside of the frame. Adjust the Anchor
Point
of the Null Object to align with the center of the lamp housing. Rename
this layer "Light Parent." Com-mand+Click to select all the layers in
the timeline except for the two background layers and the Light Parent
layer. Once selected, go to the Parent column for this layer and set it
to "Light Parent."

Now, by selecting the "Light Parent" layer you can move the light to
any position in the composite. Move it to the left and down a little so
that the bottom of the lamp is flush with the bottom of the
composition. By rendering a separate AlphaLens pass, we have the
freedom to move the lamp to any position without having to re-render
the reflection.

From the menu select Composition>Save Frame As>File and name your
file "completed_scene" and click Save.
The default file format for AfterEffects is a Photoshop.psd file; if
you want it saved in another format you can change this now. Clicking
Save brings up the Render Queue dialog box. Under
"Light Assembly 1" set the Render Settings to Best
Settings, then set the Output Module to
Lossless.
Click on the Render button and wait. If for some reason your result
isn’t what you expected, we’ll bring you a finished file that will be
archived with this tutorial in a future online.

Support Gear:
Software: Adobe After Effects 6.5

David Bell and Lisa Yimm, leaders with DVGarage’s Pixel Corps Training
Program and founding members of the VFX production house, INDVFX.

Carrara 4 makes it easy to take advantage of multi-pass rendering for
maximum flexibility when compositing in After Effects. We’ll show you
how to composite a lamp into a background scene including real
reflections and faked transparency.

The files in this tutorial are named with a leading number to make it
easier to organize the workflow. In a future version of this tutorial
that will appear online, a complete set of pre-rendered images,
including a 3D object, background, multiple passes and final rendered
files, as well as an After Effects comp file, will be available for
download.

Source Material:

A 3D object and background created in Carrara 4

INDVFX
www.indvfx.com
e-mail:info@indvfx.com