As in the threetwo-dimensional case, the eigenvalues <math>\lambda_1,\lambda_2,\lambda_3</math> of <math>S_w[p]</math>, and the corresponding eigenvectors <math>\hat{e}_1,\hat{e}_2,\hat{e}_3</math>, summarize the distribution of gradient directions within the neighborhood of ''p'' defined by the window <math>w</math>. This information can be visualized as an [[ellipsoid]] whose semi-axes are equal to the eigenvalues and directed along their corresponding eigenvectors.<ref name="Medioni"/><ref>{{Cite journal|last1=Westin|first1=C.-F.|last2=Maier|first2=S.E.|last3=Mamata|first3=H.|last4=Nabavi|first4=A.|last5=Jolesz|first5=F.A.|last6=Kikinis|first6=R.|date=June 2002|title=Processing and visualization for diffusion tensor MRI|url=https://linkinghub.elsevier.com/retrieve/pii/S1361841502000531|journal=Medical Image Analysis|language=en|volume=6|issue=2|pages=93–108|doi=10.1016/S1361-8415(02)00053-1|pmid=12044998}}</ref>
[[File:STgeneric.png|thumb|center|240px|Ellipsoidal representation of the 3D structure tensor.]]
