With Estimate Surface Area, the surface area of the structure is estimated by counting voxel surfaces (Algorithm 1) and by using a method based on statistical measures (Algorithm 2).

Algorithm 2 calculates an approximation of the surface area by statistical methods and not simply by adding up the voxel surfaces. Therefore, the surface of a sphere is approximated correctly. However, the estimation is slightly biased in case of highly anisotropic media. The method originates from statistical image analysis, where the determination of the four Minkowski measures (Volume, Surface Area, Integral of mean curvature, Integral of total curvature) from voxelized images is an essential task. To determine the surface area, the Crofton formula is used, which relates at first the 3D surface area to an integral over 2D boundary lengths of planar cross sections and then second these lengths to an integral over 1D rays. Based on this formula, an analysis of the intersection points of rays in all space directions with the structure allows determining the surface area.