Using BCC Motion Key in Autodesk Flame to remove a foreground object from a scene

In this exercise, we'll use the BCC Motion Key spark within the Autodesk Flame host to remove a moving foreground object from a scene which does this without rotoscoping or heavy compositing.

• Import the clip MotionKeyBefore.mov, which is a 2 second clip Artbeats stock clip DSF110.mov.
• Load the BCC Motion Key Spark into one of the open sparks slots.
• Click on the BCC Motion Key Spark and select the MotionKeyBefore.mov clip for both front and matte inputs.
• Click on a destination reel to enter the spark user interface.

• Scrub the clip to familiarize yourself with the motion of the car in the clip - this is the foreground element that we will remove.

To remove the unwanted foreground element, in this case the car that passes through the intersection in the center of the frame, we need to show the filter where this car is in the frame on every frame. We achieve this by keyframing the set-up region over time so that on every frame it encompasses the pixels that are to be removed from the scene. By default the remove area region is an oval shape - we'll change this to a rectangle and keyframe the position of the rectangle over time.

• By default the filter is set to the setup region mode.

• Click on the area shape pop-up and select Rectangle from the list.

• Move to a frame where you can see the entire shape of the car so that we can correctly set the size and aspect ratio of the rectangle.

• If you have not already done so, disable the auto-key function.

• Position the region rectangle over the center of the car.
• Set the area scale to 2.0.
• Set the area aspect ratio to -1.6.

• Enable the autokey function.
• Move the cti to the start of the clip.
• Reposition the rectangle so that it is centered on the car.

• Move through the timeline, keyframing the position of the rectangle once every 15 frames, as it moves from left to right across the frame.
• The last keyframe should position the rectangle out of the frame.
• Scrub through the timeline to ensure that the car is covered by the rectangle on all frames and make adjustments (adding keyframes) as necessary.

The next step is to remove the car.

• Click on the mode pop-up which now shows setup region and select remove area from the list.

• Scrub through the effect to ensure that the car has been eliminated from every frame.

• Process the result.