Motion Tracking & Object Tracking inside Cinema 4D: Motion Tracker Object Attributes Part 2

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An overview of the Motion Tracker Object Attributes.

An overview of the Motion Tracker Object Attributes. The "2D Tracking" Tab. Here, we set the parameters for both Automatic and Manual 2D trackers.



The 2D Tracking tab is dedicated to, well, 2D tracking. This is the process of generating, tracking, and tweaking the 2D tracks, and can range from fully automated to fully manual. Let's focus on the attributes now. In the Automatic Tracking tab, we can see the settings for the generation and tracking of auto tracks. Number Of Tracks and Minimum Spacing defines how many automatic tracks will be generated, and how close they can be to each other. Although initially the auto tracks seem to generated randomly, actually the algorithm places them on high contrasting features of the current frame. Auto Replace Lost Tracks is a function that adds more trackers to the scene when the previous ones are lost, either because the feature exited the frame, or if an object obscures it. This setting guarantees a healthy number of tracks on every frame. Create Auto Tracks creates automatic tracks for the specific frame you're on. We use this when we feel that at a specific frame, the automatic tracks are not sufficient. Then we have the big button named Auto Track that has two arrows, one on each side, and then two separate arrows. These buttons do different things depending on the following condition. If there are no automatic trackers in the scene, you know, the ones you created with the Create Auto Tracks command, this is what's going to happen. It will first create a bunch of auto trackers based on the above attributes. Number of tracks, minimum spacing, and auto replace. Then it will load the footage into RAM and finally it will track bi-directionally, which means forwards and backwards, or in one specific direction if you selected one of those single arrows. And after these operations are done, you will have a full 2D track to inspect, refine, and do a 3D solve. On the other hand, if you have any auto tracks already created, it will load the footage and run the 2D solve without creating any more. Mind you, if you're adding your own automatic trackers, the Auto Replace Lost Tracks won't do anything. In this case, you should advance to another frame and add more auto trackers. Delete Auto Tracks deletes either any selected trackers, or all automatic trackers in the scene if none are selected. Finally, the filters allow us to filter based on four rules. Filtering means hiding and ignoring the tracks because they are of bad quality and will lead to a bad solve. Minimum Length will ignore tracks with less than the set number of frames. Maximum Acceleration helps filter out trackers that jitter suddenly, which sometimes means that it has jumped to another feature. This parameter basically compares the previous distance to the current, and decides if there's too much of a difference between them. If that's the case, the algorithm assumes it's because the tracker jumped to another feature, which essentially invalidates the track. Error Threshold deletes tracks whose error is above the set value. The error is defined by comparing the recorded pattern and the current pattern. The bigger the difference, the higher the error. Lastly, the Smart Acceleration works alongside the Maximum Acceleration, but takes into account the motion of the neighboring trackers, to identify if a track jumped or if the camera just did a sudden motion. If the camera did do a sudden motion, that will make all neighboring trackers move in a similar manner, therefore considering them valid. The Manual Tracking tab has the equivalent buttons, but for manual trackers, to track bi-directionally, forwards or backwards, and for deleting. Underneath, we have a list of all our manual trackers, their naming field, and parameters for the search size and pattern size for each selected tracker. Finally, the Options tab is where we set pattern and search size for automatic trackers, some display options, and the Extrapolate Search Position. This is a setting that I have found little use for, so just ignore it. The last setting is for adding the object track name to any manual tracker that has been assigned to a specific object track. Since we can have more than one object trackers in the same scene, it helps to know which of the manual trackers belong to which of the object trackers. For the time being, just leave it off. And this concludes our overview of the 2D Tracking tab. In the following tutorials, we will see more of these in action.
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