Method of motion vector derivation for video coding

An apparatus for motion information derivation for blocks of a picture, the apparatus comprising one or more electronic circuits configure to:

• receive input data associated with a current block;
• derive a plurality of affine parameter motion vectors based on spatial and temporal neighboring blocks of the current block;
• add the plurality of affine parameter motion vectors into a Merge candidate list with a predetermined order as an affine merge candidate;
• determine a current sub-block located at a current sub-block location within the current block;
• calculate a derived sub-block motion vector for the current sub-block based on an affine motion-model function depending on the current sub-block location if the affine merge candidate is selected, wherein the motion-model function is represented by F(x,y)=a×x+b×y+e, and wherein (x,y) is the current sub-block location and a, b and e are affine model parameters associated with the affine motion-model function and are determined based on the plurality of affine parameter motion vectors;
• and
• encode or decode the current sub-block using the derived sub-block motion vector for the current sub-block.