One embodiment of the present invention includes a system comprising to determine a direction of tracking a fiber based on a vector corresponding to a largest value of a set of values for a tensor, if an anisotropy value of the tensor is greater than or equal to a first threshold; and to apply a weighted function to the vector of the tensor to select the direction of tracking the fiber, if the anisotropy value of the tensor is less than or equal to the first threshold and larger than or equal to a second threshold. In one embodiment, the system is to generate the weighted function comprises a linear interpolation to be performed on the vector. In one embodiment, a weight of the linear interpolation is in part dependent on the anisotropy value of the tensor, wherein the weight corresponds to the anisotropy value relative to the first threshold. One embodiment of the invention is also executable as a method.