October 17, 2011, 02:53:40 pm
@Morten: I was also curious...

(you never know when you get into a similar trouble so best is to be prepared)
BTW I went back to the original file and did this change (only the "culprit" material swapped with another material already in the file: Bod_Schiffsboden) then did nothing special (not even cleanup) just a simple Purge (under Model info > Statistics) as it should be regularly done anyway and the file went down to 13 Mb and exported from SU just fine and imported to Lumion perfectly.
It's still a bit messy. There are a bunch of simple colours that I do not know where they are coming from. Maybe group/component materials but I did not go further to investigate because I wanted to only make this change to see if that material was indeed the culprit.
Originally there were a whole bunch of small fragments of the asphalt for instance. I have no idea where they came from because they purged perfectly.
@Alain: it was not only the size (as that could have been helped by resampling easier) but that image was buggy.