Creative Effects > Distort > Refining Distortions >
Working with Correspondence Points

Correspondence points indicate how one frame is mapped to another in relation to source and destination splines, or Input1 and Input2 source splines when using source interpolation. If part of a clip is pulled or shifted too much during a distort, you can realign it by adjusting the correspondence points.

By default, correspondence points are added automatically. You can display the points, move them around the splines, animate them, as well as add and delete points to create a correspondence that better suits your needs. The more correspondence points a spline has, the more control you have over how the warp or morph is mapped.

To show correspondences:

1. Toggle on the visibility of the source splines and destination splines using the Show buttons.
2. In the Distort module, click Correspondences.

   Correspondence points are shown on the source and destination splines, and are connected by dotted lines. Selected splines show the connections with yellow dotted lines; unselected splines shown them in grey.

   (a) Correspondences of unselected spline (grey)(b) Correspondences of selected spline (yellow)(c) Selected spline in Distort schematic

To move correspondence points:

1. Click Correspondences to display the correspondence points.
2. Select Move mode from the Edit box, then click and move a point on either the source or destination spline.

   You can also select multiple points by Shift-clicking them.

   Points can only be moved between the two points that surround it on the spline.

   The correspondence point can only be moved between the two surrounding points

   Image courtesy of Behavior Communications Inc.

   The warped or morphed region is remapped according to the changes made to the correspondence points.

To add correspondence points:

1. Click Correspondences to display the correspondence points.
2. Select Add from the Edit Mode box.
3. In the region of the clip where you want to improve the mapping, click the source or destination spline to add a new correspondence point.

   A point is added. As well, a corresponding point is added to the corresponding spline. You can then move either of these points to improve the mapping of the clip. The more correspondence points there are, the more refined the distortion.

   Adding a correspondence point to a source spline adds one to the destination spline

   Image courtesy of Behavior Communications Inc.

To animate correspondence points:

1. Move to the frame where you want to begin animating correspondence points.
2. Display a source and destination spline by clicking the Source Show and Destination Show buttons.
3. Click Correspondences to display correspondence points.
   TipThe source and destination splines should be offset from one another to best be able to animate their correspondence points.
4. Enable Auto Key in the Distort menu.
5. Select Move mode in the Edit box, and then move one, or more, correspondence points to a new location.
6. Advance the positioner to a different frame and then move a correspondence point again.
7. Continue to move correspondence points as you progress through the clip to refine the warp or morph over time.

   Correspondence point animation for each spline is kept in a corresPts channel in the Channel Editor. See Distort Animation Channels.

To delete correspondence points:

1. Click Correspondences to display the correspondence points.
2. Select Delete from the Edit Mode box.
3. Click a correspondence point on the source or destination spline.

   The point you clicked and the corresponding point on the corresponding spline are deleted.