I am working with conversion of OSM files into geo-spatial databases for my master thesis. When I tried to select an area of ~20 km^2 from JOSM to download and save, it said 'requested area size too large' and that I should use extracts provided by the community. So I downloaded the OSM for Bonn, Germany. The Problem is, this area is too large for my purposes. Is it possible to select a smaller area from this OSM extract and save that as an OSM file with JOSM or any other free source graphical software?
Thanks!!
If you want a small to medium sized extract you could also use the "mirrored download" plugin of JOSM. It uses the Overpass API to download the data (instead of the main OSM Servers) and allows quite large extracts. On the plus side you always get the most up-to-date data and you don't have to download more data than you actually need.