Howdy-

Let's say you have an ROI that you converted to a dset, such as following this example in the Bootcamp:
[www.youtube.com]
... by running the following:

ROI2dataset -prefix tuna.lh.niml.dset -input tuna.lh.niml.roi

Indeed, the tuna.lh.niml.dset dset does just contain the list of nodes in the ROI region. NB: if you wanted the above output as a *1D.dset, you could run the following with the "-of ..." option to specify "output format":

ROI2dataset -prefix tuna.lh -of 1D -input tuna.lh.niml.roi

You can use ConvertDset to make a "full" dset. You basically have to provide the max index that you want your dset to have, either as a number, an ld* value (related to MapIcosahedron), or by providing an example dset with appropriate size of mesh (probably what I would personally prefer):

ConvertDset -input tuna.lh.niml.dset -prefix full_tuna.lh -o_1D -pad_to_node d:std.141.lh.sulc.niml.dset 

# have 2 columns of data: one is value at each node, 2nd is list of node indices:
ConvertDset -input tuna.lh.niml.dset -prefix full_tuna.lh -o_niml_asc -pad_to_node d:std.141.lh.sulc.niml.dset -add_node_index

Does that do what you want?

--pt