[OSM-dev] Which is best for this task, osmosis, osmconvert osmupdate or...

[Paul Norman]

On 12/29/2015 9:41 AM, Dave F. wrote:
> I've previously download a file of all OSM data within a rectangular 
> area. I then use mkgmap to convert it to the format by my Garmin GPSr. 
> In the future I'd like to change that so it's a multi faceted polygon 
> of only specified OSM entities.
>
> At present, each time I want to update the file, I'm downloading every 
> entity, even if they haven't been amended. What I need is to download 
> any changes within the polygon since I last updated. I read about 
> minute, hourly & daily diffs. Am I able to state the date I last 
> updated as the start point for new data?
>
> There appear to be a few programs able to do what I require, but 
> unsure which is best suited. Is Osmosis a bit overblown for my 
> purpose. Osmupdate seems a bit more lightweight. Osmconvert appears to 
> discourage doing what I need: 
> http://wiki.openstreetmap.org/wiki/Osmupdate#Use_Cases. Overpass also 
> has a way to download diffs. Anyone used that?

Your best bet is to get an extract from Geofabrik which contains the 
areas you need and use their daily diffs to keep it up to date. If you 
need a smaller area, extract it from this larger file every day.

> Is it better to work with a raw OSM data file or use a .pbf file? In 
> fact I'm a bit confused what one is. From the wiki it firstly says 
> "alternative to the XML format", but then goes on to compare it with a 
> compressed file format. Which is it?

OSM PBFs are raw OSM data, as is OSM XML and o5m. They're just different 
file formats. Avoid OSM XML unless you're using software which only 
supports that. Use PBF or o5m instead. PBF is easier to use with the 
workflow I describe above since you can download a PBF directly from 
Geofabrik.