New issue 774: We shouldn't need to extend the transfer function https://bitbucket.org/yt_analysis/yt/issue/774/we-shouldnt-need-to-extend-th... Matthew Turk: I don't remember why we do this anymore -- NaNs? running of the edges? segfaults? -- but we typically extend the TF, and we shouldn't need to do this. Responsible: samskillman