Before you assume that the task will be relatively straightforward, I recommend that you pay a visit to the following web site:
http://www.hollywoodcamerawork.us/vfx_index.html You'll see how the pros do it.
Furthermore, you'll probably want to avoid the use of AE entirely: since you'll hjave to shoot the live action first, you'll have to animate in 3D to the live action. A 3D application is best for this task, not AE.
3d tracking a scene is never "nothing too complicated".
The most important step is having a good script.
Other steps following that will include planning, storyboarding, shooting the scene (with enough tracking markers - or trackable elements - in the right places in the shot), shooting a clean plate (also, take the chance to grab some ambient room noise for your audio editing later), and shooting an HDRI - note: this is not an all-inclusive list.
That was all just pre-production and production.
Steps in post would include tracking the shot, modeling the 3d elements, texturing the 3d elements, lighting the 3d elements, animating the 3d elements, rendering the 3d elements and their various passes (object buffers, ambient occlusion, shadows, lights, motion vectors, depth pass, etc.), compositing your 3d elements into the scene (which will involve color correction and may or may not involve keying, rotoscoping, and other techniques - you'll figure this out during the planning stages), rendering out your composite in a proper intermediate codec, bringing your final shot into your editing program, adding sound design, color grading, and producing a finished file in the correct delivery codec. Again, there is more to it than this, but these are some of the basic steps.
Thank you. I'm new to this. The assumption I've made thus far is that it is not a straightforward process. But that's okay with me. I use Carrara 8 Pro for my 3D so I can pose this question on that forum as well. I was hoping that importing live footage into AE and using its new 3D capabilities would allow me to achieve my result.
Szalam, regarding your post, are there any good tutorials you'd recommend?
Each one of the steps I mentioned is so complex that it can be someone's entire career. Some people's entire job is matching the motion of a scene and building a 3d equivalent for simulations. Some people just do 3d modeling. Some people just do 3d texturing. Some people just do rotoscoping.
There are myriads of tutorials for each of the steps and none of them will cover every possible scenario. Books are written about each of the steps.
Anyway, I do have some good tutorials to recommend for starting out in After Effects. Bonus: THEY'RE FREE! Check them out here.
Just to give you an idea of one work flow you could use, here is a very simplistic AE camera track with a 3D door that uses Element 3D from Video Copilot as a way to be accessed in AE. It was merely an exercise exploring the process.
Please view at 1080P and full screen .
And here is another exploration without the camera tracking. Element has limited animating capabilities so as the other folks suggested, Cinema 4D might be better suited to your needs. You be the judge.
Also best viewed at 180P and full screen.
Start at the beginning: Plan the shoot. And as Szalam and Dave said, this is anything but straightforward or simple. AE's 3D tracker is useless for this kind of thing. You need to use a tool that spits out a 3D scene that you can use in your 3D program to align things.
Actually, if you're using Cinema4D, AE's 3d tracker can be used. If you go to Maxon's website, you can download two new plugins for After Effects, one lets export your AE scene as a Cinema 4D scene. So, if you create null objects in the right places in After Effects, you'll be good to go.
Granted, other programs can do this better, but if you don't have the money, at least there's this option.
Do you know of a list of 3D programs AE's camera data will export to? I've been googling without much luck. I'm interested in knowing if it works with Daz3d's Carrara 8 Pro.
The only one I know of is Cinema 4D. There is no 3d program that integrates with After Effects as well as C4D by a long shot. The C4D to AE export is amazingly useful.