Hi there,
The general recommendation would be to normalize the streamlines to template space, and then generate the ‘number of connections’ image in template space. This is preferable to warping a density image, as the orientation dependence of density modulation based on expansion / contraction in the warp field will be performed correctly.
There is however a little trickery in deriving the appropriate warp images to perform that normalization, and it also depends on the software used to perform the registration. Unfortunately we still haven’t added a tutorial on this point to the documentation… the post here would be a good starting point.
Cheers
Rob