Tensor visualization

When you need to visualize the tensors estimated by the DTI track module, you must first save them from thr DTI track module, see related documentation for more details). You can then load them in the tensor viewer module by clicking ``Open a tensor field''. It can take a little while before the tensor field is fully loaded.

Then you may need to press ``center'' to center the view on the tensors in the 3D window (see figure 4.1). You can choose between different visualization modes to display the tensor field. Figure 4.2 explains these different modes. Default setting is ``cubes'' mode. It will represent tensors as rectangular rhombs. For all modes, the main diffusion direction of the tensor is shown thanks to a RGB color code, and brightness is weighted by the Fractional Anisotropy (FA) of the tensor. You can downsample the displayed tensors for faster rendering.
NB: The ``ellipsoids'' needs more RAM memory of your computer than the other modes.

Figure 4.2: On the left you can see the visualization parameters located in the left panel of the Tensor viewer module. On the right are shown differents sets of parameters. Tensors on the left correspond to default parameter values. Those on the middle have been displayed with a greater ``glyph size'' (25). Finally tensors on the right have been displayed with a more precise resolution (15). The sample rate controls the fraction of tensors to display (i.e. 1: all tensors; 2: one tensor every two; etc).