i wrote a josm plugin that does all the math and marks the border of
every canvec tile
some of the tiles match my grid perfectly, and match eachother with no
overlap or gap
other tiles are offset slightly and dont fit the grid or eachother
by checking the grid in my plugin, i can tell which node is in the
'correct' spot, because the canvec edges are always a certain fraction
of a degree
On 01/30/2012 06:36 PM, Samuel Longiaru wrote:
But which is the "right"position? When one is given to be 3 cm's off
the other, neither is more accurate, given the data collection
technique. I think you are beyond the accuracy of the data themselves
at that level. While merging and then combining a stream or a road
that crosses a tile boundary, trying to decide which node is more
"accurate" is one of those questions best asked only during periods of
intensive navel contemplation. Take either one. The precision of the
data exceed their accuracy I would guess by several orders of
magnitude. Is the next node along the way mapped to 3 cm accuracy?
Or the next, or the next? No. Here is an example where "good enough"
is TRULY "good enough". It's all the science can bear.
Sam
-----Original Message-----
*From*: michael bishop <cle...@nbnet.nb.ca
<mailto:michael%20bishop%20%3ccle...@nbnet.nb.ca%3e>>
*To*: Talk-CA OpenStreetMap <talk-ca@openstreetmap.org
<mailto:talk-ca%20openstreetmap%20%3ctalk...@openstreetmap.org%3e>>
*Subject*: Re: [Talk-ca] canvec data offset
*Date*: Mon, 30 Jan 2012 18:01:04 -0400
yeah, thats what i had to do for every node
but part is the issue there, is that when i merge 2 nodes, it doesnt
always go to the 'right' position'
need to manualy select them in the right order to make it go in the
right direction, it seems more like an error in the canvec data then
an extra step i need to do on every tile
almost looks like floating point rounding errors, but not sure why
some tiles are ok and others arent
On 01/30/2012 05:56 PM, Samuel Longiaru wrote:
Have you tried just zooming back a bit in JOSM and merging them?
It's part of my stitching process for each tile. I've never had a
merge refused because of a 3 cm difference (but, of course I've never
looked that closely to see how far apart they were actually). We're
dealing with precision here... not accuracy at that level.
Sam
-----Original Message-----
*From*: michael bishop <cle...@nbnet.nb.ca
<mailto:michael%20bishop%20%3ccle...@nbnet.nb.ca%3e>>
*To*: Samuel Longiaru <longi...@shaw.ca
<mailto:samuel%20longiaru%20%3clongi...@shaw.ca%3e>>
*Subject*: Re: [Talk-ca] canvec data offset
*Date*: Mon, 30 Jan 2012 17:42:42 -0400
yeah, its not much, but its enough to screw up josm when trying to
combine things between the 2 tiles
have to fix each node on the border one by one, no real patern to
which direction they are shifted
even along a solid line (the edge of the tile), the nodes are going
up&down and zig-zagging across the edge
On 01/30/2012 05:31 PM, Samuel Longiaru wrote:
I can hardly put my finger to my nose to within .03 meters... and
that's not even drunk. :)
Sam L.
Kamloops
-----Original Message-----
*From*: michael bishop <cle...@nbnet.nb.ca
<mailto:michael%20bishop%20%3ccle...@nbnet.nb.ca%3e>>
*To*: Talk-CA OpenStreetMap <talk-ca@openstreetmap.org
<mailto:talk-ca%20openstreetmap%20%3ctalk...@openstreetmap.org%3e>>
*Subject*: [Talk-ca] canvec data offset
*Date*: Mon, 30 Jan 2012 17:11:27 -0400
ive been working with canvec for a few days now, and ive noticed some of
the data is offset by 0.03 meters
its not matching up with nearby tiles
for example 021O10 doesnt match up with 021O07
ive noticed the problem on other tiles aswell, but didnt think to write
them down
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