Exporting Maya camera to After

    This is a simple method that we used in our experimental project, that shows how to export the camera from Maya to After Effects.
    This method is very useful when we want to avail the movement of Maya's camera into After Effects, to make compositions, for example. Because with this export of the camera's information, we have a very accurate depth reference of the elements that were in Maya, through the use of locators/Null objects.
    The procedure seems long, because it involves many steps, which can be interesting also to be seen individually (they are marked in orange). But it is quite simple:

   After we have the camera movement, first of all we must configure the Maya, to be compatible with AE:

- Go to Display Render Settings window (fourth clapperboard, in the top right)
- In Render Using, change to mental ray
- In Common, on Presets de Image Size, change to the video format that you want to use

   Other needed configuration, is to change the unit of the Maya to AE's unit:

- In Window > Settings/Preferences > Preferences, go to Settings
- And in Working Units, on Linear, change to milimeter

   Also we need to create keyframes on every frame of the Maya camera's movement:

- Go to Edit > Keys > Bake Simulation

   Now, we need to create landmarks (locators), that will help in depth reading on AE:

- Create a locator in Create > Locators
- Position the locator holding the "V", to align with the object
- Duplicate and position, repeating the procedure (if there are other elements involved)

   But to AE recognize the locators, we need to change the name of all locators to NULL:

- Select all locators (it's easy to select them all with the Maya Outliner)
- Go to Modify > Search and Replace Names...
- In Search for:, put locator
- In Replace with:, put NULL
- Click in Replace

  That done, we just need to export to .ma.

- Select the camera that you want to export, and the locators (remember that with the Outliner, it's more practical)
- Go to File > Export Selection (on box)
- In General Options, on File typ:, change to mayaAscii
- In Include Options, only marks the Channels
- Click in Export Selection and define the output

   And import this .ma archive to AE:

- Go to File > Import > File... and search for .ma archive that you exported
- On the Project tab it'll apear two elements: a composition and a folder
- Click twice on composition, to see it
- Notice that inside there are the NULLS (they're the locators tha we created) and a camera
- If we move the Time Indicator, we can see the camera's movement

   After that, to make sure that our AE's camera movement matches the Maya movement:

- On Maya, generate a playblast
- On AE, import this playblast and drag it to the layers of the composition
- Increase size with the Scale, selecting the playblast layer and pressing "S"
- Increase it to match the composition size

   Done! Now if we move the Time Indicator, we'll see that the movement matched perfectly.
   Remember that if something has not been so clear, for lack of something visual, this video tutorial that I used is very good, and explain it all.

http://cg.tutsplus.com/tutorials/autodesk-maya/quick-tip-exporting-3d-camera-data-from-maya-into-after-effects/ by Jostein Finnekasa