How to Fake a UFO Landing

The magic of Voodoo.
Sticking In the Pins

In Blender, importing your track data will give you something like what is shown in Figure 3.

Figure 3. Blender File with Voodoo Track Imported and Point Cloud Showing

The point cloud is a representation in 3-D space of the track points from Voodoo, and the camera has applied to it all the animation data (pitch, yaw, roll, position and lens length) to re-create the movement that the original camera engaged in. It is possible that upon import you will need to re-orient parts of your scene, but if you've done your job properly all that needs to be done now is to finish your 3-D UFO (texturing, animation and so on), and create your dust cloud with your particle engine. Marrying these elements together with the tracked footage is a job for your compositor—Blender has a quite capable one built in, which I covered in depth in the October 2007 issue of Linux Journal.

Figure 4. Finished Shot

With a bit of practice, you'll have your own fake UFO video suitable for posting on YouTube or fooling media pundits. Like anything, camera tracking takes practice to get right, but the toolset provided by Voodoo puts this technique well within the reach of any hobbyists willing to learn a bit about optics and spend some time training their eyes. Refer often to the on-line help—Voodoo is one of those rare freeware products with excellent documentation built right in.

Until an open-source camera tracker of equal sophistication presents itself, Voodoo likely will remain the only free camera tracker for Linux—at least in a price range that end users can afford. All hail the grad students and their advisors at the University of Hannover, Germany. Let's hope their excellent work remains free to use for the foreseeable future!

Dan Sawyer is the founder of ArtisticWhispers Productions (, a small audio/video studio in the San Francisco Bay Area. He has been an enthusiastic advocate for free and open-source software since the late 1990s, when he founded the Blenderwars filmmaking community ( He currently is the host of “The Polyschizmatic Reprobates Hour”, a cultural commentary podcast, and “Sculpting God”, a science-fiction anthology podcast. Author contact information is available at