I was always wondering if the robots in transformers had millions of parts like LEGOs and the different parts snapped on and off and rotated in a completely mechanical way, but I feel like the VFX artists cheated a lot and make parts appear and disappear magically out of thin air. What do you think? I am not sure if this is the right place, but the robot sequences is VFX and this stackexchange seems to be about VFX.
1. They HAVE to cheat
First of all, having a part that is not showing in the frame will consume render time to be computed, even if it is not showing. The files are heavier to handle and all the process becomes sluggish.
2. Transforming in a 3D program is given by 3 main operations
- Rotating, which they are pretty obvious in a transformation.
But you also have
- Scaling. If you have something scaled so tiny that you can not see it, the geometry is still there consuming resources of the computer that are wasted.
3. The goal is
Telling a story, a fantasy story about fictitious characters, not to be accurate on a transformation.
The other main goal is to make things look cool, somehow logic and accurate but mainly cool.
4. Autobot's universe actually has parts that "disappear"
Take for example the Spark humungous building-sized cube. It does not only compress in size to be handheld... It would have the density of Jupiter nuclei, weighing the same as a building. But somehow things there just went "poof"... So, again some liberty can be used on the transformations.
Animations like this are always created within 3D tools like blender, Cinema 4D or other 3D engines. Basically you have a 3D scene with all the objects that you can select, rotate and move. You put them together like you want them when for example representing the robot. Then you save this state with all the positions of the single objects.
When transforming the robot to a car, the objects are animated to rotate in a specific way, or or maybe break into many single pieces. But all of this is done in other programs and sometimes there might be a kind of programming behind it to define specific animations.
After everything is ready and animations are set up, you can render the movement and export the whole thing as a movie clip. This is just a basic explanation to understand the single steps of creating the animation and then using the created clip for the edit. If you want to learn more about it check out this movie. In fact, it is even more complicated and before they could create the animation they also created little models of these transformers