Open topic with navigation

Tracking Still Frames

Before you do anything else, you need to tell CameraTracker which still frames you want it to track and how it should distribute the tracking features on each frame. Then, you can track your still frames.

Selecting the Frames to Track

• Input - the default value, sets the frame range to the length of the sequence attached to the Source input.

• Global - sets the tracking frame range to the range set in the Project Settings frame range controls.

If no frame range is defined, the frame range of the first image you read in is used as the Global frame range.

• Custom - sets a tracking range of frames described by the from and to fields.

• Reference Frames - allows you to manually set keyframes on the frames you want to analyze.

• To set all frames in the input as reference frames, set the Add dropdown menu to Add All . Any missing frames on the input are skipped.

• To set a specific frame range as reference frames, set the Add dropdown menu to Add Range. In the dialog that opens, enter the frame range in the Frame range field and click OK.

• To set individual frames as reference frames, set the Thumbnails dropdown menu to All at the top of the Viewer. Then, scrub to a frame you want to set as a reference frame and click the add reference frame button . The current frame is set as a keyframe and displayed in the thumbnail gallery at the bottom of the Viewer.

Scrub to the next frame you want to add as a reference frame and repeat the process until you're happy with your set of reference frames.

TIP:  If necessary, you can also use the delete reference frame button or the Delete dropdown menu in the CameraTracker properties to remove frames from the set of frames to analyze.

Adjusting the Features to Track

For example, if you're using the alpha channel from a Roto node attached to the Mask input, select Mask Alpha. For more information, see Masking Out Regions of the Image.

NOTE:  For stereoscopic or multi-view footage, set the Principal View on the CameraTracker or Settings tab to the main tracking view. Any masking should be applied to this view, which is then used to calculate the secondary camera.

• Number of Features - define the number of features you want to track in each frame.

Ideally, you should use more than 200 tracks per frame. In most cases, the default 250 should be sufficient, but in difficult solves you may consider using twice that number.

• Detection Threshold - set the distribution of features over the input image.

If you enter a low detection threshold value, features are tracked evenly on all parts of the image and vice versa.

• Feature Separation - set the distribution of features in relation to each other.

To force feature separation and spread features evenly over the image at even distances, enter a high feature separation value.

Preview comes in handy when you want to tweak the tracking parameters further before tracking - it updates dynamically when controls are adjusted.

It's important to make sure that the previewed features are distributed evenly and not clustered together too densely before tracking using the distribution and separation controls.

Tracking the Selected Frames

CameraTracker begins by detecting viable features, aligning the reference frames, and then tracking forwards. Tracks that don't meet the quality thresholds set in the Settings tab Tracking controls are reseeded so that the number of tracks remains constant.

When the playhead reaches the end of the sequence, it begins a verifying pass by reading the frames sequentially backwards. Any tracks that were reseeded due to error are tracked back past the point where they were created, if they remain viable.