Figure 3.

Schematics of data processing methods. Nanoparticle on curved substrate (a). Solid lines denote the substrate and the nanoparticle, respectively, and the dotted line denotes the path of the AFM tip. The convolution effect on used data processing algorithms: (b)--nanoparticle projection, (c)-- nanoparticle volume at minimum basis, (d)--nanoparticle volume at Laplacian basis. Light gray represents the nanoparticle. Medium gray shows the nanoparticle as seen by AFM (after tip convolution), dark gray represents volume determined by the data processing algorithm. Note that even Laplacian basis cannot properly determine the whole nanoparticle volume as the surface geometry below nanoparticle is unknown. As the power spectrum-based algorithm is a global one, it cannot be illustrated within this schematic figure.