<br><br><div class="gmail_quote">2009/3/26 William Lachance <span dir="ltr"><<a href="mailto:wrlach@gmail.com">wrlach@gmail.com</a>></span><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hey all,<br>
<br>
I've been following the discussions about the geobase import with<br>
interest. There seems to be some concern about how to correlate the<br>
existing OSM data with the Geobase dataset. In particular, how do we get<br>
the superior positioning and connectivity of geobase without blowing<br>
away all the great work people have done tagging their manually inputted<br>
ways?<br>
<br>
This topic is of some interest to me, as I've been using both GeoBase<br>
and OSM data in a project of mine called <a href="http://hbus.ca" target="_blank">hbus.ca</a> (linky:<br>
<a href="http://hbus.ca" target="_blank">http://hbus.ca</a>), which is basically a transit mapper for the Halifax<br>
Regional Municipality. Right now, I'm using OpenStreetMap data for the<br>
map view, and geobase information (the NRN road network) for the site's<br>
geocoding and pathfinding capabilities. From my perspective, it would be<br>
really great to get the GeoBase information in for Halifax, as OSM<br>
coverage for the outer areas of the HRM is rather poor.<br>
<br>
One alternative which I haven't heard mentioned is the possibility of<br>
_merging_ the two datasets. That is, writing an automated script that<br>
does the following for a given region:<br>
<br>
1. Look up all named OSM ways.<br>
2. For each way:<br>
- Finds the corresponding GeoBase segments with the same name and the<br>
same proximate positioning. Obviously some cleverness will be required<br>
here. I've written a geocoder which should be able to help with the<br>
naming bit. The positioning part is a computational geometry problem<br>
which can be solved in a number of ways -- I'd need to do some<br>
experimenting to see what works best.<br>
- Merge any tags from the existing OSM way (e.g. cyclespeed) which<br>
cannot be expressed with the GeoBase road gml files.<br>
- Replace the OSM nodes with GeoBase ones.<br>
</blockquote><div><br>It is nice to application using OSM data. Regarding your approach, one of the problems I see to use street name to match both data sets is that GeoBase and OSM do not have the same data model. For example, an OSM way does not break at road intersections where GeoBase does. So in practice you'll many GeoBase matches for on OSM way. On more problem is that not all GeoBase data sets have names. In Nova Scotia you are lucky you have name and block face addresses, but it is not the cases forl the provinces. I am in favor of the geometry matching approach. I priorise the OSM existing data so I extend or shorten Geobase segments to integrate them to the existing osm data. I agree with you : it would be nice to have a full OSM coverage and GeoBase is a good source to achieve this goal. <br>
<br>Michel <br> </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><br>
As a disclaimer, I've never written any code which actually interacts<br>
with the openstreetmap server (I've only done operations on raw OSM<br>
files), so there might be a step or two I'm missing. Other than that,<br>
can anyone see a reason why this wouldn't work? Ordinarily this is<br>
something I'd just go ahead and try (I'm planning to give it a shot next<br>
week), but I thought I'd bring it up here now since the topic is up for<br>
discussion.<br>
<font color="#888888">--<br>
William Lachance <<a href="mailto:wrlach@gmail.com">wrlach@gmail.com</a>><br>
<br>
<br>
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</font></blockquote></div><br><br clear="all"><br>-- <br>Michel Gilbert<br>