No discussion of OSM would be complete without a discussion of licensing and copyright. OSM makes this particularly complex because the project is in the process of changing their license from CC-SA-BY to ODbL. For a full discussion, I recommend the OSM Wiki, but the short version is:
- CC-SA-BY (Creative Commons, Share-Alike, with Attribution) is a license that says that anyone can use a work and modify it, as long as attribution to the original author is maintained and the terms don’t change for the derived work. This isn’t particularly surprising, it’s a typical “open source” license, similar to the GPL.
- ODbL (Open Database License) is a slight twist: with the ODbL, anyone can use the original data, but if you modify the data, you have to give back your changes. You don’t have to make your derived works open source though. (So under the ODbL if you build custom scenery out of OSM, your scenery doesn’t have to be open-source licensed, but if you ‘fix’ any roads, you need to submit the fixes back to OSM.)
OSM is CC-SA-BY now and is working to switch to ODbL. Basically their lawyers realized that CC-SA-BY is great for images and text, but isn’t actually legal for databases (which is what OSM is). The ODbL will protect OSM as it is – that is, as a “database”. Since OSM is a huge open project, the license change is going to take a long time and lots of people will post lots of rants on lots of mailing lists in the process.
Here’s our plan: we are going to make the v10 global scenery abide by both the spirit and the legal requirements of both licenses. (At least, I hope we are going to try to do this. I am not a lawyer and wouldn’t mind if this was all a lot simpler.)
- The version 10 DSFs will be CC-SA-BY. This means that you can modify and redistribute the global scenery DSFs. In the past, we haven’t officially supported this, but we’ve allowed it to go on in the community. With version 10, modifying DSFs will be officially okay. (Please note that copying the sim DVDs will not be okay. You can modify our DSFs, but we are not inviting anyone to sell pirated DVDs! X-Plane is still a commercial product!)
- We are encouraging all users to improve OSM directly in the OSM database – we will not accept modified DSFs as a way to fix roads. (This helps us comply with the ODbL.)
- All of the scenery tools used to create the global scenery will be open source.
This last case is important because we do a lot of processing to the raw OSM data before we create the DSFs. Technically we are required by the ODbL to “give back” thsoe changes, but the truth is that I don’t think anyone really wants the hundreds of GB of temporary files we create as we process. So instead we will give back the tools that do that processing, so people can recreate our processed database as desired. From my discussions with OSM community members, this is apparently an acceptable way to ‘give back’ our changes.
I should say that nothing is guaranteed here. Heck, it’s even possible that OSM will change its license in a way that screws up the whole global scenery project before we ship. (This is highly unlikely – I’m just saying that there is legal uncertainty with OSM that we haven’t had to deal with when using other data sources.) But I think we’ll be okay; X-Plane’s use of OSM (to create a mash-up of OSM plus other data sources like SRTM elevation to create a derived copyrightable work like a DSF) is definitely one of the use cases that OSM wants to make possible.