[Talk-ca] Map Error

Bob Dustan bob.dustan at gmail.com
Mon Oct 25 14:04:16 BST 2010


Hi Sam,

I just updated the affected area using LIO WMS to trace from. 
Incidentally, LIO matches up with Google imagery fairly well.

Bob


On 10/25/2010 12:40 AM, Sam Vekemans wrote:
> Hi,
> Yes.  Thats most likely correct.  This happens across the country
> along the NTS border lines.
> You might want to check the GeoBaseNHN data, as it could be better.
> (since its organized in water basins)[1]
>
> Then we can go 1 level deeper, into the Land Information Ontario
> dataset.   A WMS layer is available [2] as well as the source shp
> files.  (I do have direct access to it (via a data warehouse loginID)
>
> [1]
> wms layer for JOSM  (found on this page
> http://wiki.openstreetmap.org/wiki/Geobase/NHN_-_OSM_Map_Feature)
> http://wms.cits.rncan.gc.ca/cgi/wms_en.cgi?map=/export/wms/mapfiles/rhn/geobase_rhn.map&version=1.1.1&service=WMS&request=Getmap&layer=HYDRO_AGGREGAT&format=image/png&STYLE=default&layers=GEOBASE_RHN_NHN&
>
> [2]  http://wiki.openstreetmap.org/wiki/Land_Information_Ontario#Data_Access_-_WMS_Layers
> You'll have to dig... i'm not exactly sure where the river WMS is..
> but i do remember seeing it.  The Ontario servers are considerably
> slower than NRCan, so you'll need to be patient :)
>
> You might want to try using  Merkaartor, as it can handle WMS layers
> alot better.
> http://wiki.openstreetmap.org/wiki/Merkaartor
>
> Cheers,
> Sam
>
> P.S.   great to hear from another Ibycus Topo user :)   One of my
> projects is to make a better version of it, now that more data is
> available.   I don't know if Dale Atkin is planning on doing the same
> at some point.
>
>
> ---
> Across Canada Trails - Beyond 2017 - The National Trails Network
> Victoria, BC Canada
>
> Twitter: @Acrosscanada
> Blog: http://acrosscanadatrails.posterous.com/
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> Skype: 'Sam Vekemans'
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>
>
>
> On Sun, Oct 24, 2010 at 2:16 PM, Gordon Dewis <gordon at pinetree.org> wrote:
>> Interesting. I wonder if it's an artefact left over after the NAD27->NAD83 conversion.
>>
>>  --Gordon
>> -----Original Message-----
>> From: Bob Dustan <bob.dustan at gmail.com>
>> Sender: talk-ca-bounces at openstreetmap.org
>> Date: Sun, 24 Oct 2010 14:30:45
>> To: talk-ca<talk-ca at openstreetmap.org>
>> Subject: [Talk-ca] Map Error
>>
>> Hi,
>>
>> I was importing CanVec data for 031E07 and noticed what appears to be an
>> error in the map.  A section of the Oxtongue River seems to be repeated
>> nearby in 031E06.  In OSM you can see it at:
>>
>> http://www.openstreetmap.org/?mlat=45.317&mlon=-79.0&zoom=15&layers=M
>>
>> If you use JOSM or Merkaator to view this area and enable the NRCan WMS,
>> you'll see that the error is also in the WMS version of the map.
>>
>> The error also appears in "The Atlas of Canada" (Toporama) web site at:
>>
>> http://atlas.nrcan.gc.ca/site/english/maps/topo/map?layers=nodata_ntdb_50k%20north_arrow%20other_features%20million_grid%20t50k_grid%20grid_50k_3%20roads%20hydrography%20boundary%20builtup%20vegetation%20populated_places%20railway%20power_network%20manmade_features%20designated_areas%20water_features%20water_saturated_soils%20relief%20contours%20toponymy%20contour&scale=1400000.000000&mapxy=1281552.5697346777%20-273673.4692181579&map_layer[northarrow]_class[0]_style[0]=ANGLE%20-14.587661326428645&mapsize=750%20666&urlappend=
>>
>> The error also appears in the Ibycus map.
>>
>> Also, if you look north along the boundary between these 2 map sections,
>> you will see other discrepancies.
>>
>> I have topo maps of the area that I bought at least 10 years ago.  They
>> appear to be scans of paper maps.  When I line up the 2 map sections,
>> everything lines up (roads, rivers, elevation lines, etc.).
>>
>> It seems to me that some errors (albeit fairly minor) were introduced in
>> the digital form of the map.  Then the errors were propagated to CanVec.
>>
>> Is there a way to get the map corrected?
>>
>> Bob
>>
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