Motion Tracking with Continuum Complete

Many of the Continuum Complete 3.0.2 filters include the integrated motion tracker. Continuum Complete also includes a Witness Protection fillter which lets you apply an effect to highlight or obscure an area. For example, you could track a logo on a t-shirt and obscure the logo with a blur effect. This all made possible with the magic of motion tracking.

This tutorial uses a QuickTime movie as example footage. The clip was provided courtesy of ArtBeats, www.ArtBeats.com. However, you can use any clip that you like.

Note: When you use the Motion Tracker parameters in any filter, the Canvas window must be set to 100% to track correctly. You should also deselect Show Square Pixels in the Canvas window.

Lets Start the Motion Tracking

1. Click to select the clip in the timeline that you want to track. Move the playhead to the first frame of the clip that has the area to track.

If your clip starts before the area to track appears onscreen, use then Razor Blade tool to create razor edits around the section that you want to track. When you finish razoring the clips, click to activate the Selection Tool and apply the BCC filter to the razored section.

2. Choose Effects > Video Filters > BCC3 Effects> BCC3 Witness Protection. Alternatively, drag the BCC Witness Protection filter from the Video Effects folder in the Effect tab in the Browser to the clip in the timeline.

The effect is applied to the selected clip.

3. Double-click the clip with the applied filter to display the filter parameters in the Viewer's Filter tab. Make sure the playhead is on the first frame of the clip to display it in the Canvas.

4. Choose the appropriate effect from the Effect Method menu. This tutorial uses the Mosaic effect to obscure an advertisement on a trolley. However, you can use whichever effect you like. You can apply a mosaic, blur, tint or brightness/contrast effect.

You will use the parameters in the Mask parameter group to set up the region that you want to obscure.

5. Adjust the Region Radius to sets the size of the area to obscure. This example uses a value of approximately 6.

Note: In this example you need to animate the size of the Region Radius, because the target region grows larger as the trolley moves closer to the viewer. In your image, the size of the area to obscure may remain constant as it moves across the screen.

6. Use the Offset X and Offset Y parameters to position the mask over the area that you want to obscure. This example will obscure the blue advertisement on the right front of the trolley.

7. It may be difficult to see the area that is affected. Setting the View Mask menu to Chosen Pixels or Mask Unchosen Pixels can help you to finetune the area.

View Chosen Pixels displays the matte in black and white. Black regions represent the unfiltered pixels; white regions represent the filtered pixels. Gray areas represent partially filtered pixels. This is useful for adjusting an area that is difficult to see, for example a subtle Blur. Mask Unchosen Pixels displays a 50% red mask over the unfiltered pixels. This is also useful for adjusting an area that is difficult to see.

8. You may need to adjust Stretch to finetune the shape of the masked area. Stretch distorts the oval-shaped region by stretching it either horizontally (positive values) or vertically (negative values). This example doesn't use the Stretch parameter.

9. Return the View Mask menu to Output.

10. Use the parameters in the Effect parameter group to finetune your effect.

• When Mosaic is chosen, Amount/Brightness sets the pixelation along the horizontal and vertical axis. Set this value to approximately 5.

• Contrast/Scramble shuffles the pixels in the image. As Scramble increases, the pixels become increasingly random.
• Seed determines which value is input tothe random number generator used toscramble the pixels. If you like, you can adjust this parameter. The Color controls have no affect when Mosaic is chosen.

11. Scroll down to the Motion Tracker parameter group. You will use the parameters in the Motion Tracker parameter group to setup the Target. The Target indicates the area in the media to track.

A good target region contains a high-contrast object with good vertical and horizontal edge definition. Ideally, you should find a pattern that is visible in every frame.

12. With the playhead on the first frame of the effect, select the Track On-the-Fly checkbox. A white rectangular outline indicates the target area that will be tracked. When you select this checkbox, the effect no longer displays. Once you finish tracking, deselect this checkbox to play the applied effect.

13. Create a keyframe for the Tracker Center KF. This is important if you need to adjust the tracker later in your effect.

14. Click the crosshair in the Tracker Center KF control to enable the onscreen position point. Manually set up the Tracker Center KF at the first keyframe. These controls set up the area to track. In general it is easier to use the onscreen point controls.Then use the position controls for finetuning.

15. Adjust the Target Size. This sets the size of the area to track. Increasing this value increases preview time but can increase the accuracy of the tracking. However, if you make the area too large, a similar pattern might accidentally be tracked.

16. Analyze the motion by choosing Mark > Play > Every Frame. The filter generates tracking data.

17. Deselect the Track On-the-Fly checkbox.

The effect that you created now uses the motion tracker data to follow the target area.

18. Render the effect just as you would render any Final Cut Pro effect.

Correcting Motion Tracking Errors