How To Solve Motion Tracking Issues In Mocha

How To Solve Motion Tracking Issues In Mocha

December 19, 2019
Ben Thompson

Run through a quick checklist of fixes for your tracking issues!

From wire and object removals to tracking complex footage, Mocha provides VFX artists with an array of tools for creating a perfect motion track.

Since properly tracking footage takes a little time, it’s easy to run into problems such as offset tracking data or even tracking drift. Today, we’re going to look at a few ways you can overcome problematic motion tracks in Mocha and nail a solid track.

Run Through the Tracking Checklist

Before you pull your hair out and spend too much time floundering, Boris FX provides an incredibly helpful YouTube video that runs through six questions you should ask yourself when running into tracking issues.
Here’s a breakdown of the questions from their YouTube video:

1. Have I created my tracking data in the [Mocha] plug-in?

You’ll want to make sure you don’t neglect this crucial step! If you’re running Mocha AE CC, remember to click the “Create Track Data” button after completing the track in Mocha. This allows the data to transfer from Mocha to After Effects.
You’ve probably got the latest version of the plugin, but the video cautions there are older versions that require you to additionally select the process cog beside the layer you want the tracking data applied to. Make sure the cog is present beside the layer you need.

2. Have I applied it to the right layer?

Simply clicking “Apply Export” won’t automatically apply your data to the correct layer. First, choose the layer you’ll want to target in the drop-down menu beside “Layer Export To,” and you should be all set.  

3. Is it the right type of tracking data?

Figure out if you need transform data or corner pin data when performing your track. The difference is transform data applies one point of positional data (position, rotation, and X & Y scale). Corner pin data utilizes all four points of positional coordinates (Top Left, Top Right, Bottom Left, Bottom Right).
Source: YouTube | BorisFX https://youtu.be/sZu-KQtCY3I
You can uncheck anything you don’t need to avoid the risk of wonky tracking data!

4. Is my Surface set correctly in the Mocha interface?

While it can be easy to use the tracking shape to gauge the success of the track, you need to also keep in mind the surface data is critical to achieving a track that will translate well.

Turn the surface tool on and adjust accordingly to ensure a smooth and seamless track once you pop back into After Effects. For more help with tracking planar surfaces, the video above refers you here.
Source: YouTube | BorisFX https://youtu.be/sZu-KQtCY3I

5. Are my tracked footage and insert clips the same resolution?

We’ve all been there. You’ve painstakingly built your track in Mocha, only to switch over to After Effects, apply your tracking data, and the image you wanted to insert is moving appropriately, but it’s hundreds of pixels off. Here’s how to fix it!

This can be a really easy one to overlook, but oftentimes a culprit for distorting tracking data can be when you have a difference in resolutions. You have to make sure the resolution is consistent across the media you’re working with.  

If you’re overlaying a graphic onto a 4K comp, but your graphic is any size other than the size of the comp, you’re going to run into issues. You can fix this problem by pre-comping your insert graphic to match the resolution of the main comp prior to applying your tracking data to the graphic. Once you’re in the composition with your insert graphic, make sure you right-click the insert layer, and select Transform>Fit to Comp. 

Once you set your insert’s pre-comp to match the main composition (including using Fit to Comp), then apply your tracking data, it should be smooth sailing!

6. Am I sure my tracked footage and insert clips are the same resolution?

Just another reminder of the importance of question #5! If you have any mismatched resolutions floating out there in your project, you’re probably going to experience issues. Just make sure all layers are set to the same comp size using the steps mentioned above, and it should really help curb those offset tracking issues.

How to Correct Tracking Drift in Mocha

If you’ve gone through the checklist and you’re still having issues, fear not! Tracking drift can occur in certain situations, so let’s take a look at how to circumvent that with the awesome AdjustTrack module in Mocha.
If you’re struggling with reflections, shadows, or occlusions in your source video, the AdjustTrack tool allows you to place reference points throughout your source video to give you additional keyframing control. 

By adding this extra information, you can greatly alleviate drift in the track. Make sure to watch the video above for full instructions on how to best utilize AdjustTrack.

Armed with these tips, the AdjustTrack tool, and some solid footage, your next motion tracking project should go much smoother!

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