[HOT] Call for volunteers: Somalia roads import
mail at harrywood.co.uk
Mon Aug 22 13:51:39 BST 2011
I imported and merged in one of the Somalia road files
Most OSMers probably don't have the confidence to undertake such a thing. It's is the first time I've actually done any OSM importing myself. Maybe I was being more careful than I needed to be, but I thought it might be helpful to give a little walk-through of what I did. Either as instructions to others, or perhaps for people to tell me where I've done it wrong!
--- Steps ---
Download the chosen .osm file and open in JOSM
File -> new layer then download OSM data covering the same area (and a bit more). I needed to do this peice by peice because the are was too large for a single download (although not much data being returned by the server)
Using the layers panel to flick between datasets. Visual compare. look for overlapping areas for road.
For me there were no existing roads in OSM to worry about apart from in the town on Burao http://www.openstreetmap.org/?lat=9.5151&lon=45.5441&zoom=14 I did a general sanity check on the rural roads data, comparing bing (landsat) The MadMappers roads are mostly not visible in this, but they seemed follow logical well lined-up paths through mountains and along valley bottoms. I decided to upload the data to OSM first (creating duplicates in Burao) and then make a few de-duping fixes after that.
Go to openstreetmap.org 'logout' then 'sign up' to create a new user account for imports (if you don't already have one) e.g. 'Harry Wood Import' Verify email address etc.
back in JOSM Edit preferences. 'Connection Settings' panel. Swap to new username and password
Click upload. Set the source=MadMappers-SOM-2008-01 on the changset
I had 13,000 objects. This took 20 or 30 minutes to upload as a diff. I'm not sure if there's a better (more robust and less strenuous on the server) way to do this. Perhaps switching to "atomic" mode would be a good idea for this.
back in JOSM Edit preferences. 'Connection Settings' panel. Swap to my normal username and password.
Delete all layers and re-download the OSM and MadMappers data (now munged together on the server)
--- Fixup ---
From this point onwards I was just doing normal editing. Uploading
regularly, and I didn't set a source tag (what is the source for fixing
up an import? 'common sense'?)
The existing data by User:roage was a few main roads in the town. These lined up pretty well with the data from MadMappers, but was more crude. It mentioned source=landsat in various places, although I hated to do this, I mostly deleted User:roage's contributions in favour of the MadMappers data. However User:roage's data included stuff off the edge of the area I was dealing with so this survived. I had to cut and re-connect these ways with the imported data (main roads coming into Buroa from the south west)
In the MadMappers data itself there were some duplicates in the town. I didn't seed ways directly on top of each-other, but there was highway=track alongside highway=secondary. These were side-by-side like dual-carriageway or in places braiding over the top of each-other. Although this might have reflected some sort of reality, I'm guessing not, particularly as the highway=secondary was also surface=unpaved anyway. Clearly there is one main (but unpaved) road following this route through the town. So I guess this is the "doubled/overlapping roads" Schuyler is referring to. I imagine this is probably data from two surveyors munged together messily. So I deleted the highyway=track and made the necessary reconnections.
I used the validator plugin to find a few bugs, particularly ways ending near another way (should be connecting)
In the town main roads were broken up into separate ways pretty much at every junction. This isn't really the norm for OpenStreetMap. Where streets can be represented as one long way, they normally are. So I spent a long time doing 'combine ways' to try to group thinks logically. This was the most laborious bit of manual effort I did in fact.
Most OSMers probably don't have the confidence to undertake such a
thing. It's is the first time I've actually done any OSM importing
myself. Maybe I was being more careful than I needed to be, but I
thought it might be helpful to give a little walk-through of what I did.
Either as instructions to others, or perhaps for you to tell me I've
done it wrong!
And finally most minor roads in the town have come through in the Schuyler's conversion as highway=unclassified, but some are highway=track. I found some of the more major roads (judging by the logic of the grid layout) were highway=track. Clearly all the roads here are unpaved, so might be called "tracks", but highway=track implies less major than a highway=unclassified, so I swapped these to highway=tertiary to make the road layout of the town make sense.
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the HOT