Phil:

Okay, trying to have "track" read single-precision floats instead of double doesn't do it either:

SEVERE: Exception in thread "main" class misc.LoggedException: Invalid number of components in input data. Check -inputmodel and -numpds options
at tractography.DT_TractographyImage.(DT_TractographyImage.java:106)
at tractography.DT_TractographyImage.getDT_TractographyImage(DT_TractographyImage.java:277)
at apps.StreamlineTractography.execute(StreamlineTractography.java:972)
at apps.EntryPoint.main(EntryPoint.java:226)

So an accidental type mismatch doesn't seem to be the problem.

If you can't think of anything obvious, then I'll just take a closer look into the code after the holidays.

Thanks again so far, and happy holidays!
TR