New Feature: Playlist Center! Pick a topic and let our playlists guide the way.

Start learning with our library of video tutorials taught by experts. Get started

Maya Rendering for After Effects Composites
Illustration by John Hersey

Applying motion tracking data to a null layer


From:

Maya Rendering for After Effects Composites

with Lee Lanier

Video: Applying motion tracking data to a null layer

We placed the spaceship layer over the background footage. Now we're ready to try to motion track the ship so it matches the camera movement of that footage. Let's take a look at it. One thing you'll notice is that there is more chaotic motion, particularly at the beginning, also the fact of the camera's rotating or tilting left and right. If you watch the top of the building, you can see how that perspective changes quite a bit. That tells us two things. One, we need to have the tracker figure out the rotation of the camera. Two, the fact that there is lot of chaotic motion at the beginning of the footage, means that you probably want to do the tracking from the end of the timeline towards the beginning, in terms of analyzation.
Expand all | Collapse all
  1. 2m 0s
    1. Welcome
      47s
    2. Using the exercise files
      1m 13s
  2. 29m 49s
    1. Working with image sequences
      7m 24s
    2. Importing reference video as an image plane
      5m 13s
    3. Matching the 3D camera to the video footage
      4m 23s
    4. Lighting the model
      5m 35s
    5. Creating mattes and shadows in preparation for rendering
      7m 14s
  3. 15m 38s
    1. Using the Render Layer Editor
      4m 21s
    2. Splitting a scene into multiple render passes
      6m 6s
    3. Adding flexibility by assigning material and render overrides
      5m 11s
  4. 15m 2s
    1. Creating render passes using mental ray
      3m 50s
    2. Batch rendering render passes: Project one
      5m 24s
    3. Batch rendering render passes: Project two
      5m 48s
  5. 19m 4s
    1. Importing render passes into After Effects
      6m 25s
    2. Recombining render passes in a composition
      6m 31s
    3. Transforming multiple render passes as a single unit
      6m 8s
  6. 48m 7s
    1. Setting up a motion tracker
      5m 17s
    2. Using a tracker to analyze motion in footage
      3m 56s
    3. Adjusting tracker options for better results
      7m 2s
    4. Matching layer motion by applying tracker data
      6m 26s
    5. Refining a layer's transparency with rotoscoping
      6m 45s
    6. Improving layer movement with the Smoother tool
      5m 7s
    7. Improving the CG by adding blur and effects
      8m 7s
    8. Adding shadow to make the composite believable
      5m 27s
  7. 32m 36s
    1. Recombining render passes for project two
      5m 17s
    2. Removing unwanted elements with a garbage mask
      4m 57s
    3. Applying motion tracking data to a null layer
      6m 38s
    4. Adjusting shadows and matte edges
      8m 12s
    5. Using color correction to improve layer integration
      7m 32s
  8. 25m 46s
    1. Stabilizing shaky video with the Tracker
      8m 2s
    2. Tracking rectangular elements with the Perspective corner pin option
      5m 31s
    3. Adjusting corner pin points and paths
      6m 56s
    4. Applying corner pin data to multiple layers
      5m 17s
  9. 1m 16s
    1. Next steps
      1m 16s

Watch this entire course now—plus get access to every course in the library. Each course includes high-quality videos taught by expert instructors.

Become a member
please wait ...
Maya Rendering for After Effects Composites
3h 9m Intermediate Aug 17, 2012

Viewers: in countries Watching now:

In this course, professional animator and director Lee Lanier shows how to create render passes in Autodesk Maya, recombine the passes in Adobe After Effects, and motion track the passes to live-action video footage that contains a moving camera or a moving character. The course covers both the Render Layer Editor and mental ray contribution pass systems. Additionally, 1- and 2-point motion tracking and match moving, stabilization, and 4-point corner pin tracking are discussed.

Topics include:
  • Working with image sequences
  • Matching the 3D camera to video footage
  • Lighting models in Maya
  • Splitting a scene into multiple render passes
  • Batch rendering
  • Recombining render passes in an After Effects composition
  • Setting up motion trackers
  • Refining layers with rotoscoping
  • Adding blur and effects
  • Adjusting shadows and matte edges
  • Using color correction
  • Stabilizing shaky video
Subjects:
3D + Animation Rendering Textures Video Materials Compositing Visual Effects
Software:
After Effects Maya
Author:
Lee Lanier

Applying motion tracking data to a null layer

We placed the spaceship layer over the background footage. Now we're ready to try to motion track the ship so it matches the camera movement of that footage. Let's take a look at it. One thing you'll notice is that there is more chaotic motion, particularly at the beginning, also the fact of the camera's rotating or tilting left and right. If you watch the top of the building, you can see how that perspective changes quite a bit. That tells us two things. One, we need to have the tracker figure out the rotation of the camera. Two, the fact that there is lot of chaotic motion at the beginning of the footage, means that you probably want to do the tracking from the end of the timeline towards the beginning, in terms of analyzation.

When we go to the last frame, let's apply a tracker. I'm going to pick shot2, go to Animation, and apply Track Motion. Now in order to have it to figure out the rotation, I need to select the Rotation check box right here, Position is turned on automatically, in this case I need Rotation also. When you click on Rotation, you get a second track point, that's necessary to figure out how the camera is tilting, so track point 1 and 2. The idea is you place these over two separate features. Let's take a look, I'll zoom back.

We are fortunate in the fact that there are two lights in the side of the building that are good candidates for this. I'll place track point 1 on the left one and track point 2 on the right one. So I'll zoom in and just click-drag these by the empty portion of the center to reposition them, so track point 2 will go over this light here. Now the track point boxes are smaller then the light feature, so I am going to expand this box--just want them to encompass that feature loosely. So here is track point 2, now track point 1, there we go. Let's try to analyze this from the end of the timeline backwards.

All right, let's take a look at track point 2, that's looking pretty good, now track point 1. It's here already on frame 0, it slipped off, and however, the rest of the motion path looks pretty solid, so you could go in and adjust the track points to continue to reanalyze or check the options in the tracker. In this case, though, because I only have maybe two frames that are incorrect, I think I'll manually place the track point. So on frame 0, I'll drag it back up to where it needs to be, and in frame 1, do the same. All right, that's looking pretty good. So now we have motion paths for these two track points, we can apply it to the spaceship.

Now there is a potential issue. Normally when you apply the tracker to a layer, it keyframes the properties. In this case, because we have Position and Rotation, if I apply to spaceship, it's going to animate position/rotation here. Therefore, although I can offset the positions to the anchor point, I cannot offset the rotation unless I change the resulting keyframes. That could be a lot of work. So one thing we could do to avoid this potential problem is apply the tracker to a Null and then parent the ship to the Null.

Now what's a Null? A Null is a special layer inside After Effects, it doesn't actually render. It has a set of Transforms which you can apply something like a tracker to and parent things to but doesn't occlude anything below it. So if I apply the tracker to a Null, then parent the ships to the Null, I'm free to later adjust the position offset or rotation offset on the ship layer itself. Let's try that. Now there is one thing we should probably do before we apply it though to the Null, and that is remember that the tracker applies the data based on where the anchor point is for the layer, so the anchor point is basically stuck to the motion path.

Now in this case, because we have two track points, that'll be stuck to the motion path for track point 1. So we really want the anchor points for the Null on the spaceship over here where the track point 1 is. Let's go back to the composition view. So here is the spaceship. While we have that, let's go and select that layer and move it to anchor point from here, down to where the light is for frame 0. Let me go to frame 0. I want to use Pan Behind tool to move that, and I'll zoom in so I can see it better. So there is pretty much the center of that track point 1 for that frame, frame 0.

Okay, so we need a Null. I have already created a Null inside After Effects, you go to layer > New > Null Object, and there is a Null, it comes in as a red bar, it's indicated by red square inside the viewer. Now this doesn't actually interfere with the final render, it's just there for reference. It also has its own anchor point at the top left, and that's red. So while we had a Pan Behind tool activated, let's try that over also, I want to put in the same place, about right here. By doing that when we apply the data, it's going to make that the ship is pretty much where it needs to be right here.

Okay, I'm going to go back to the Selection tool. Now there is one another step we should take, we fix the anchor point for the Null, fix it for the spaceship, but we have to think about what to do with the matte. Remember the mattes supplying the Alpha to the ship, so it needs to travel also, so I'm going to do that through parenting. I'm going to parent the map layer to the ship and then make the ship follow the Null. I am going to parent the ship to the Null, so matte is parented to the ship, the ship is parented to the Null. So now we're ready, fix the anchor point to care the parenting, we have the Null, now we can apply the data.

Now we go back to Shot2 and make sure I can see the motion tracking, click the Edit Target, select the Null, click OK, then apply the data, Apply, and Yes for X and Y. So here the Null has picked up the motion tracking data, and therefore the ship is following the Null and the matte is following the ship. Now there is a problem. You see how it's rotated? Looks like it's a little off kilter there. Let's play it back until it's going on. So the ship feels like it has the same motion as the camera, so the motion tracking is therefore successful.

However, it's off a bit in terms of rotation, but since we use the Null, we can offset that. Now the Null itself has the position/ rotation animation placed on it by the tracker. Now if I go down to the spaceship layer, you can see the position/rotation are still free. So what we can do is change the rotation--offset the rotation and get the ship back where it needs. In fact, if you enter 7.5 into the Rotation, it snaps back down to where it needs to roughly be, on top of the building. Now it's not exact match yet. We left those planes we placed in Maya little bit loose, so our layer step will deal with a really tight fit, but at least the ship is rotated correctly now.

We'll play it back, rotation is now correct. Beside from the edge tightness here, eventually there is the issue of the fact to seeing cut off here, but we'll deal with that in the later step. So we have successfully motion tracked this footage through two track points with rotation and position and applied that to a Null, and the Null basically drives the ship and the matte layer along.

There are currently no FAQs about Maya Rendering for After Effects Composites.

 
Share a link to this course

What are exercise files?

Exercise files are the same files the author uses in the course. Save time by downloading the author's files instead of setting up your own files, and learn by following along with the instructor.

Can I take this course without the exercise files?

Yes! If you decide you would like the exercise files later, you can upgrade to a premium account any time.

Become a member Download sample files See plans and pricing

Please wait... please wait ...
Upgrade to get access to exercise files.

Exercise files video

How to use exercise files.

Learn by watching, listening, and doing, Exercise files are the same files the author uses in the course, so you can download them and follow along Premium memberships include access to all exercise files in the library.
Upgrade now


Exercise files

Exercise files video

How to use exercise files.

For additional information on downloading and using exercise files, watch our instructional video or read the instructions in the FAQ.

This course includes free exercise files, so you can practice while you watch the course. To access all the exercise files in our library, become a Premium Member.

join now Upgrade now

Are you sure you want to mark all the videos in this course as unwatched?

This will not affect your course history, your reports, or your certificates of completion for this course.


Mark all as unwatched Cancel

Congratulations

You have completed Maya Rendering for After Effects Composites.

Return to your organization's learning portal to continue training, or close this page.


OK
Become a member to add this course to a playlist

Join today and get unlimited access to the entire library of video courses—and create as many playlists as you like.

Get started

Already a member?

Become a member to like this course.

Join today and get unlimited access to the entire library of video courses.

Get started

Already a member?

Exercise files

Learn by watching, listening, and doing! Exercise files are the same files the author uses in the course, so you can download them and follow along. Exercise files are available with all Premium memberships. Learn more

Get started

Already a Premium member?

Exercise files video

How to use exercise files.

Ask a question

Thanks for contacting us.
You’ll hear from our Customer Service team within 24 hours.

Please enter the text shown below:

The classic layout automatically defaults to the latest Flash Player.

To choose a different player, hold the cursor over your name at the top right of any lynda.com page and choose Site preferencesfrom the dropdown menu.

Continue to classic layout Stay on new layout
Exercise files

Access exercise files from a button right under the course name.

Mark videos as unwatched

Remove icons showing you already watched videos if you want to start over.

Control your viewing experience

Make the video wide, narrow, full-screen, or pop the player out of the page into its own window.

Interactive transcripts

Click on text in the transcript to jump to that spot in the video. As the video plays, the relevant spot in the transcript will be highlighted.

Are you sure you want to delete this note?

No

Thanks for signing up.

We’ll send you a confirmation email shortly.


Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

Keep up with news, tips, and latest courses with emails from lynda.com.

Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

   
submit Lightbox submit clicked
Terms and conditions of use

We've updated our terms and conditions (now called terms of service).Go
Review and accept our updated terms of service.