On Dec 9, 2008, at 2:13 PM, Martin Kampmann wrote:

Hello,

I just downloaded the new Chimera version and tried to combine
different models (density maps) into one volume, using the new
'combine' function, (e.g. combine #1 #2), but it returned an error
message.

Is it only possible to combine atomic structures (such as PDB files),
or is there a way to combine volumes/density?

Yes, "combine" can only combine molecular models. I'm not even sure how you would combine maps unless 2 out of 3 of their dimensions were the same and they were precisely aligned along the remaining axis.