Applying an overlay
Suppose that object transformations are determined for a continuous range of video frames.
If an image of a patch is now pasted onto the selected frame in a fixed position, then, by applying the corresponding transformations, the patch can be warped and propagated to all other frames in the range. The result will look as if the patch was glued to the object:
A patch image applied in this way is called an overlay, and the frame where its position is fixed, a match frame.
When the output transformation layer corresponding to several segments
is not continuous, PatchMaker will apply the overlay only to its continuous
part containing the match frame.
See also :
In addition to a still overlay consisting of a single image, PatchMaker can work with a live overlay represented by a video sequence. In such a case, each overlay frame will be transformed and applied to the corresponding underlay frame. In fact, a still overlay is treated by the program as a video sequence with identical frames and duration equal to that of the composition.
Normally, an overlay image will have an alpha channel with pixel transparency data. Depending on the way it was created, the transparency values may have different interpretations, defined by the corresponding overlay property.
The overlay line of the Trackline panel defines the position of the overlay in time, its trimming, and match frame position.
See Tutorial 1 for a detailed example of overlay application.
