Tuesday, July 21, 2009

OSM: What You Can Do

I've been working with OpenStreetMap (OSM) data this week. The great thing about OSM (besides already containing a huge amount of road data) is that you can edit and correct data - that is, OSM manages the problem of "crowd sourcing" world map source data.

I get email from people all the time, saying "how can I help fix my local area of the global scenery". With OSM, you can help., by improving OSM's source data.

Here are two things that will matter in the quality of generated scenery:
  1. The oneway tag. Roads that are one-way need to have this tag, or the conversion to X-Plane might have an incorrect two-way road in place. If you don't see the one-way arrows on the OSM map rendering then this tag might be missing.
  2. The layer tag. When roads cross, "layer" tells OSM which one is on top (and that they do not intersect). Similarly, if a highway is underground, it's because it has a negative layer. If the layer tag is missing, complex intersections will probably render as junk.
In the US, a lot of OSM is built off an import of the TIGER census road map. Unfortunately TIGER in its previous released form does not contain one-way or layering information. So particularly for US cities, adding these tags will improve the road rendering a lot!

4 comments:

alpilotx said...

Ben, maybe you (or Nicolas) should put this info on the front page of X-Plane.org so you reach a much wider audience - because it is important (especially when the ultimate "go" for OSM is there).

krz said...

does that mean that xplane already uses openstreetmap data right now? (i havent used xplane for a while) but i use openstreetmap data for some rendering projects and i totally love it :) there is a lot of data for germany (bikeways, people roads,...) do you plan to use all available data in xplane long term...or is that simply too much data? could this data be streamed into xplane somehow?

Benjamin Supnik said...

KRZ:

X-Plane never uses OSM data directly. OSM must be converted into some kind of X-Plane scenery.

Some users are making third party scenery with Jonathan Harris' tool. I do not know if he uses one-way or layer. LR has not already shipped global scenery using OSM.

do you plan to use all available data in xplane long term...or is that simply too much data?

The data will almost certainly be filtered - OSM contains tons of weird stuff, whatever someone wants to tag, so it is impossible to say "I will use it all" - there can be data that we simply don't know how to interpret. For global scenery we may also have to omit some roads or ways due to file size (e.g. not include all foot or bike paths).

It will be possible to create custom scenery from OSM that is potentially even more detailed than the default scenery, for those whose machines can handle it.

krz said...

ah thats great to hear. correct streets also lead to better building placement right? does scenery generation of xplane consider roads for building placement/rotation?