[Talk-ca] OSM Geobase import: giving a try

Frank Steggink steggink at steggink.org
Sun Feb 15 17:34:05 GMT 2009


Hi,

I've sent below mail to Michel, who I met at the Sherbrooke mapping party last 
year, but I presume he's quite busy, so I'm posting it here.

I haven't really been following the talk-ca mailing list, but I would like to 
give it a try. I don't know yet how much time and energy I'm willing to spend. 
That usually comes in big lapses, just like my OSM contributions :)

I've tried to digest the wiki pages and e-mails, but it's quite a lot of 
information. It is especially hard to identify what information is still current 
and what is obsolete. Hopefully you can help me getting started by answering a 
couple of questions. I understand that the NRN data has the highest priority, so 
I'll focus on that.

1. Is there an agreed set of tags which need to be imported? There 
Geobase_NRN_-_OSM_Map_Feature page on the wiki lists a huge list of tags. Should 
  they all be converted? I assume we would like to keep the imported data 
consistent, although there will be differences between different provinces, and 
existing data will also be different.
     a. What is the final resolution about NID's? Do they need to be kept?
     b. How can we guarantee that the final import will be consistent? (See also 
my first question.)

2. Do I have to use existing software / processes, like RoadMatcher, or can I 
develop a way to import data in a way that will suit me the most?
     a. For software it makes most sense to reuse what is already available, and 
adjust it when necessary.
     b. I'm actually missing a best practice page. It is not evident what the 
most efficient process is, but that's also likely subject to personal taste / 
skills.

3. Is there an existing tool to cut the NRN data files in tiles? Or does someone 
host the NRN data which are already cut into tiles? Or is it preferred to use 
the Ibycus topo maps (and convert them to OSM)?
     a. Do the Ibycus maps contain all attributes? I don't think so, since 
they're created specifically to be used by GPSs.

4. Since it seems there are several different individual import / 
experimentation processes going on, many imports will have to be rolled back. 
(I'll create a new OSM user, so my changes will be easily detectable.) Is there 
a test server available?

[Not in the mail to Michel:]
Based on the gathered information I've developed a workflow based on PostGIS. I 
still need to test it, but if this workflow is useful, I'll share it with you. 
It will involve a certain degree of manual checks, but my experience is that 
data imports always need close attention. It is very easy to mess up things. We 
also need to take things like relationships into account.

That's about it for now. As a test area I'll probably use an area in the Beauce. 
Sheet 021L07 seems to be a good candidate. I've mapped most of the existing OSM 
roads, and there are some larger residential areas, but not too much.

Regards and thanks in advance,

Frank




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