Exercise: TV Replacement.
Click on the icon for a quick preview of the exercise and the final result.

Download an archive that contains the footage as well as the setups used in this exercise.
Put these files in your Flame system: for example under the /usr/tmp directory.

To learn how to load material into the Flame Library, see the exercise:
“Loading an archive”

Images are subject to copy rights: please read the disclaimer in the “About” section.

To set up the shot, we must connect the moving shot as the background, and the shot to which we want to apply motion as the front.

Start in Batch.
1. Drag the Library node in the Batch schematic.
2. Select the Monitor, Reflection and Flower clips. press Load.
3. Set the timebar’s length to 24 frames.
4. Drag an Action node in the Batch schematic.
5. Connect the Monitor clip to the back input of the Action node.
6. In Action’s media menu, make sure an empty media strip is selected and choose Add Input.
7. In the Batch schematic, connect the Flower clip to the newly created media input (both front and matte inputs)

8. In Action’s media menu, make sure the Flower media strip is still selected and turn it’s matte off (on the right of the strip).

A four-point track does not move the front image in 3D space, but rather pins its corners to the corners of the back image. To manipulate the corners of an image with linear segments, we’ll choose a bilinear surface.

1. In Action, make sure the flower object is selected in the Action schematic (if no object is present, create one by dragging the media thumbnail in the Action schematic).
2. Set the surface type to Bilinear instead of Flat. The Vertices menu appears directly to the left.
3. In the Vertices menu, make sure the Stabilizer is set to Track at the bottom.
4. Click Stabilizer. The Stabilizer interface appears.

Since we entered the Stabilizer with a bilinear surface, four points appear in the stabilizer menu. They must be arranged in a z-pattern.

1. Make sure you’re at the first frame.
2. Drag Tracker 1 to the upper-left dot on the screen.
3. Drag Tracker 2 to the upper-right dot.
4. Drag Trackers 3 and 4 to the lower-left and lower-right dots respectively.
5. To manipulate all four trackers at once, set the tracker selection box from Selected to Gang.
6. Drag the Reference Width and Height parameters to include the entire dots in the box (a value of about 30).
7. Drag the Tracker Width and Height to a larger size (about 60).
8. Click Analyze. The tracker determines the dots’ location at every frame.

Some trackers may fail due to the reflections in the screen. Let’s fix them one-by-one.

1. If a tracker fails, select it from the list on the left, and set the tracker selection box to Solo.
2. Move the timebar to the last frame where the tracker seems accurate.
3. Disable Fixed (below the reference settings). This will update the tracker’s reference at every frame.
4. Press Analyse again.
5. Repeat from step one with each tracker that fails.
6. Set the tracker selection box back to Selected, to see all trackers.
7. Return to the Action module.

if you are having problems, sometimes it is easier to start over tracking from scratch. To reset the selected tracker, press Reset (in the lower-right corner). To reset all trackers, press Reset All.

The result tracks fine, but the image does not reach the edge of the monitor. Let’s use offsets to adjust this. There are two ways to do this. Let’s use the interactive method.

1. Press Alt+2 to display 2-up view.
2. Set the left view to Media Front (F1) and the right view to Result (F4).
3. Zoom-out the views if necessary.
4. In the lower-right corner of the Vertices menu, enable Edit Offsets. Yellow crosshairs appear in the corners of the front image.
5. In the Media Front view, drag the crosshairs while looking at the Result view. Adjust the offsets until the front appears to fit snugly in the monitor.
Tip: To fine-tune the offsets, you can edit the values directly in the Vertices view.

A clip of a reflection has been included. Let’s composite it on top of the image to add realism. To make things simpler, let’s re-use the tracking settings we generated earlier.

1. Press Alt+1 to return to 1-up view.
2. Set the view to the Action schematic (~)
3. In Action’s Media list, select the empty strip at the bottom.
4. Choose Add Input.
5. In the Batch schematic, connect the new media input to the Reflection clip (both front and matte).
6. If a new layer was created in the schematic, delete it by dragging to the bottom of the screen.
7. Select the Flower’s axis node.
8. Choose Branch and Copy in the lower-right corner of the screen. A duplicate image is created. Make sure it is selected.
Let’s replace the source footage for the duplicate.
9. With the Reflection media strip selected in the media list, click Apply. This will replace the source of layer 2 with the reflection.
10. Display the result and scrub the timebar.

To make the reflection more realistic, let’s make a few adjustments.

1. With the reflection still selected, choose Simple Add as the blend mode.
2. Increase the transparency of the reflection.
3. Press preview. The result looks good, except for the jagged edge of the image in the monitor.
4. In the Node setup menu, change the antialiasing setting to AA 8 samples.
5. Press Preview again. The result is much smoother.

The composite is done. Optionally, you can add an output node to process and view the result in real-time. Refer to the Batch module for detailed instructions.

1. Add an Output node at the ned of the Batch schematic
2. T-click the Monitor clip so the output inherits its settings.
3. Name the output clip.
4. Set the destination to the clip library.
5. Process the clip.
6. Save a Batch setup for later reuse.