Mocha is a great program for tracking. That data can then be applied and used in other software programs such as After Effects for various reasons and uses. Such examples include beauty retouching, set extensions, and rotoscoping among others. In Mocha you can use a tool to create a tracking area. The program then goes frame by frame and tracks the area designated. You are then able to use the data from that one tracking area, or, what I will be showing today, is using that track to act as a PARENT track and link other mocha objects to it. In this tutorial, I will show how you can track a portion of the rear end of a car that’s moving, and then use that track as the parent while highlighting other portions of the car rear (license plate, logos, emblems, etc.) and linking them to that parent track. This is a great technique to use to save time. Instead of tracking two or more objects independently, you only need to track one item and parent the rest using the same data.
I will break down this technique in the following steps:
– Creating a Parent Track
– Linking Tracks
– Exporting linked tracks and example uses in After Effects
CREATING A PARENT TRACK
At the start, I already have my footage open and ready in Mocha AE. To create a parent track I am going to use the X spline tool to create an object around the large concave marking in the rear of the vehicle.
Below the timeline there is the Track forward and Track backward buttons as marked by arrow icons with the letter T. Go ahead and select the Track Forward button and allow Mocha to track the object we just created.
Once the tracking has finished, in the LAYERS PANEL rename Layer 1 to Main TRACKER as this will help identify what you are linking to.
Now that you have your main tracker, you can create new layers using the X spline tool again and link them to this main tracker to use the same set of tracked data. In this example of the car driving down the street, I am creating new layers around the license plate, Cooper title, and emblem that are all the on the rear of the vehicle and look to follow the same path as the main track layer I have created.
In order to link these new layers to the main tracker, navigate back to the layers panel, select the layer you want linked to the main tracker, and then about halfway down the window on the left you will see a option for LINK TO TRACK. Open that drop down menu and select Main Tracker to create that link.
Now these new layers you have created and linked to the main tracker follow along the same path! Congratulations!
EXPORTING LINKED TRACKS AND EXAMPLE USES IN AFTER EFFECTS
To get this tracked data out of Mocha and into After Effects where we can continue our compositing needs, simply go to EXPORT SHAPE DATA located in the lower right of the program window, a new window will open, and then choose ALL VISIBLE LAYERS and COPY TO CLIPBOARD.
Back in After Effects, create a new Adjustment Layer and then go to EDIT > PASTE MOCHA MASKS. This will apply the shape data to the adjustment layer and create its own set of masks using the main tracker tracking data. At this point, you can composite as needed. In this example, I added a BOX BLUR to the layer, increased and feathered as needed, and now I have a tracked censor on the car.
Another thing I can do is create a new solid and paste the Mocha Mask to the solid. This technique can always be used with JPEGs or other images if you wanted to track a new image onto the car or license plate.