OpenStreetMap

CanVec Import for 085F05 (Fort Providence NWT)

Posted by JamesBadger_CanVecImport on 29 July 2015 in English (English).

I am working on improving the data availability for some of the major northern Canadian arctic communities, as improving this data in OpenStreetMap will also improve the Arctic Web Map project that is using OSM data.

I have downloaded the shapefiles from NRCan and I used ogr2ogr to convert them from EPSG:4140 to EPSG:4326. Then I am importing them a layer at a time using JOSM. I am using the CanVec Feature Catalogue and OSM CanVec Feature Guide for mapping values.

For the vegetation layer “085f05_11_0_VE_1240019_2” (Wooded area classified — polygons) I imported the shapefile into QGIS and used a dissolve operation to combine all the polygons. Then a Douglas generalize filter with a tolerance of 0.0001 was applied to remove redundant vertices. This reduced the vertex count from 363,000 to 40,000. Next I opened that shapefile in JOSM and changed the tags to natural=wood and manually merged the polygons with identical polygons in the neighbouring imported tiles.

I will continue importing one layer at a time until this NTS tile is complete.

Location: Fort Providence, South Slave Region, Northwest Territories, Canada

Comment from Rps333 on 30 July 2015 at 00:53

Good luck. Please updated us on your progress

Comment from JamesBadger_CanVecImport on 30 July 2015 at 01:14

It seems I did not need to use the “1240019” layer as the “1240009” shapefile is the same thing without the classification; it would have meant I could skip the dissolve operation step in QGIS.

I also had to adjust the imported data to join with neighbouring polygons, and to avoid the polygons overlapping with other features. There is Bing Imagery in the region, so I was able to check that as well and the imported data is generally correct.

Comment from JamesBadger_CanVecImport on 30 July 2015 at 19:05

I have finished importing the CanVec shapefiles for the region.

Some of the shapefiles are not as useful: the building data is out of date and would be better served by tracing from Bing Aerial Imagery. The topographic layer is not imported for OSM. The elevation points were all cartographic spot points for supplementing the topographic layer so I did not import them. If they were points that were surveyed by levelling then I would have imported the points.

The ferry data layer is out of date as the ferry is no longer in operation and has been replaced with the Deh Cho bridge. Airport information was supplemented with information from Wikipedia.

Here is a before image on OpenStreetMap, as the tiles are currently cached:

Fort Providence

Here is an after image on ArcticWebMap with the new changes:

Fort Providence

Detail:

Fort Providence

(This is ArcticWebMap’s EPSG:3573 projection, with topographic data from CanVec added as a separate layer in our tile server’s rendering style.) Meridian Island is now visible as “The Big Snye” river is now mapped.

The next step would be to get someone more familiar with the area to map the road names and buildings. I will be moving on to mapping another community that is lacking coverage.


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