Figure 5
From: Protein surface representation and analysis by dimension reduction
Complete enclosed sphere and its 2D mappings: An enclosed spherical surface (left) is mapped using PCA (middle) and using sinusoidal cartography (right). The PCA method causes a collapse of the sphere in 2-D and cannot preserve the neighborhood relationship of the surface points. Sinusoidal cartography avoids this problem to some extent (except for the points at the boundaries of the 2-D map), but is not able to preserve the area information of the 3-D surface polygons.