Region-Based Control Points Determination for Multivector Motion Description

Motion description is a key element in region-based video,coding approaches, becoming essential for low and very low bit-rate transmissions. Among the different advanced motio-description approaches, multivector motion description (MMD) models the region motion through a variable number of motion vectors (MVs) applied on specific region points called control points (CPs). However, its application for region-based video coding would require the transmission of both MVs and CPs in order to adequately compensate each region motion. Here, a region-based control point determination strategy for MMD is proposed, which is strictly based on region contour information and the application of motion-interpolation accuracy constraints to drive the CP's location procedure. This approach offers two main advantages while keeping a reasonable computational cost: 1) it is able to operate on arbitrary-shaped regions of the image and 2) it allows the complete elimination of the transmission of any information related to the number and position of the CPs. Index Terms--Control points, interpolation, multivector motion estimation and compensation, spatial transformations, video coding.