Transparent background rendering

I’ve been panicked lately thinking about how to render my animation, frame by frame, without my computer exploding, especially since my sets are increasingly detailed. Then I saw the RGBA option for rendering images with a transparent background in Blender Internal.

Here’s what a dummy I am:

I always thought I had to render everything together. OR, I could apply a green background behind the character (using the World settings), then chroma-key away the green in a separate program and composite the solo character in front of any single background image or Quicktime movie.

Sure, that’s one way of doing it. But a total waste of time. Also, don’t ever tell people you were doing it that way because they’ll think you’re a fucking cuckoo!

Final Composite example created in Photoshop, rendered in Blender
Final Composite example create in Photoshop, rendered in Blender

What I really want is a render of my character with a transparent background, so I can easily plop any background into the scene without any other technical work.

So here’s the set-up:

One detailed set. One camera, locked down. One character moving within the scene.

The solution:

Render one full shot of your background at the highest quality possible. In the example below, I use a shot from my incomplete Workshop set:

Example of a detailed set used as a backdrop.  Rendered in Blender
Example of a detail set used as a backdrop. Rendered in Blender

Then render the character animation (with the background layer hidden in the render panel) using these settings for a PNG image with an ALPHA background:

Under the Scene Tab –>
Shading –> Alpha –> Transparent.
Output –> PNG
Output –> RGBA

Settings for rendering a character with a transparent background in Blender
Settings for rendering a character with a transparent background in Blender

Your rendered result should look something like this (assuming you’re viewing it in Photoshop), without a background.

Transparent Background rendered in Blender
Transparent Background rendered in Blender

NOTE: If you are looking at the final render in blender, you may notice that your foreground character or object has jagged edges. I certainly notice it. But check out the image in Photoshop or Gimp or whatever and you should have very smooth, clean edges.

I compiled the Puppet and the background image in Photoshop and used Dodge and Burn to match the character to the setting.

Unless your camera is moving in some dynamic way whereby you cannot have a static background image, use this technique for faster rendering and compositing.

Side note, for what I’m doing, I always render in PNG. JPEG is nice and all, but I prefer the quality of PNG, and now, I am really enjoying the transparent background option with PNG! Hope you enjoy it too.

If you have any questions, leave them in the comments below and I’ll get back you.

Cheers,