Approximately 1M sample points on projection plane for each map projection

Root link of the proposed FWD-GCA-based metric: 10.6084/m9.figshare.15020151. Approximately 1 million sample points projection plane for all map projection we studied. It is used to plot distributions and contours of traditional differential-based (10.6084/m9.figshare.15022074), GCA and the proposed FWD-GCA (10.6084/m9.figshare.15022092) metrics. Unzip all zip files to a folder named 'points_1M', and use codes in 10.6084/m9.figshare.15022095 to calculate and plot metrcis.