After you load and set up your clips in the Warper, you create meshes to define the shape and position of the input image—the original image before the warp or morph—and the output image—the result of the warp or morph. The meshes use control points to determine the change, in shape and position, and create a convincing transition from the input image to the output image.
You use two meshes, a source mesh and a destination mesh, to generate the warp effect. For instance, if you want to morph a square into a circle, the source mesh defines the input image, which is a square, and the destination mesh defines the output image, which is a circle.