View source for Volume conduction

===Boundary element meshing techniques===
Triangular meshes for the BEM can be derived from an MR scan using image segmentation techniques ([[#Wag95|Wag95]]). In this way very accurate brain segmentations can be obtained. Since these methods are never completely automatic they can be very time-consuming in practice. The question is also whether very accurate geometrical models are really needed, considering the numerical and modelling inaccuracies that are present anyhow in BEM models. Simpler and less accurate meshes can be obtained from MR images by fitting shape functions on a manually delineated brain, skull and skin ([[#Ent01|Ent01]]). By 
constraining the base functions only very course delineation suffice to derive BEM models for 
MEG.