Geoffrey,
To get the ellipsoid changeset you can visit: https://bitbucket.org/gsiisg/yt/compare/default..yt_analysis/yt
I scanned this and I didn't see anything glaringly wrong. You might want to change the comment block below class AMREllipsoidBase(AMR3DData) to match an ellipsoid ;). Anyway, very good work! I did run your scripts, and I ran into a couple issues. First, in _InEllipsoid, I had to make this change to avoid a crash: diff -r 676c7f17fb97 yt/data_objects/universal_fields.py --- a/yt/data_objects/universal_fields.py Mon May 09 20:46:16 2011 -0700 +++ b/yt/data_objects/universal_fields.py Tue May 10 15:52:39 2011 -0600 @@ -944,7 +944,7 @@ # allocate array to be filled with results from eqn of ellipsoid Inside = na.zeros(data["x"].shape, dtype='float64') # find the dimension length of the grid - dim = shape(data["x"]) + dim = data["x"].shape # allocate array for the dot product with the 3 e_vectors # need to take into account different grid side sizes dot_evec = na.zeros([3,dim[0],dim[1],dim[2]]) Second, I didn't see anything in the test3D.png image... I haven't looked into why, but the 2D image looked encouraging! Again, good work! -- Stephen Skory s@skory.us http://stephenskory.com/ 510.621.3687 (google voice)