Compositing Example
DISCLAIMER: The imagery may be kind of crude by todays standards. I created this page when I was teaching 3D animation for the first time. In 1999
| RGB | Alpha | Composite | |
|
Background Plate |
| No Alpha Channel | |
| Shadow | (black) |
|
|
| Rabbit |
|
|
|
Foreground Plate |
|
|
|
Premultiplied Alpha
Lightwave renders premultiplied Alpha channels.When putting the Layers together in Photoshop, you will see black edges around your objects, because Photoshop treats Alpha channels as being straight.
To layer properly:
- In Adobe After Effects - When Importing your Image files select - Treat Alpha as premutiplied
- In Adobe Premiere - When selecting the transparency for the video overlay (clip -> video -> Transparency) choose Black Alpha Matte.
Shadow of the moving object
I rendered the shadow seperately from the Rabbit.- By adjusting the gamma of the alpha channel I can control the shadow's density
- Rendering the shadows with no or little antialisaing and then blurring it a little incompositing can save time and can create softer shadows.
- In the Surface Panel:
- Basic Parameters: Remove the texture from the floor and make it's surface color black
- Advanced options: Set the Alpha Channel for the floor to Shadow Density
- In the Object Panel:
- In the Appearance Options for the rabbit object, activate Unseen by Camera, while leaving Cast Shadow on.