Re: [Talk-in] national parks

[Kenneth Gonsalves]

On Friday 02 Apr 2010 10:57:31 am PlaneMad wrote:
> I had compared landsat lakes in chennai and found the offset error to be
> around ~20m max. But in this case it looks like its around 100m. Given the
> low resolution, seems understandable.
> 

the yahoo satellite imagery is much more accurate - unfortunately it is at 
such low res that it is almost impossible to trace.
-- 
regards
Kenneth Gonsalves
Senior Associate
NRC-FOSS
http://certificate.nrcfoss.au-kbc.org.in

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Re: [Talk-in] national parks

[Kenneth Gonsalves]

On Thursday 01 Apr 2010 7:24:28 pm H.S.Rai wrote:
> > landsat is cool
> 
> Unable to get landsat images in JOSM on Ubuntu. able to get Yahoo!,
> for landsat it give:
> 
> "Exception occurred"

I get that in some areas - ooty town gives exception, the outskirts are ok 
(exception in some places)
> 
> JOSM -> Edit -> Preferences -> WMS has wms url:
> 
> http://onearth.jpl.nasa.gov/wms.cgi?request=GetMap&layers=global_mosaic
> &styles=&format=image/jpeg&
> 
> Can you find what is wrong?
> 
I changed 'global mosaic' to globalmosaic 

-- 
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Kenneth Gonsalves
Senior Associate
NRC-FOSS
http://certificate.nrcfoss.au-kbc.org.in

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Re: [Talk-in] national parks

[PlaneMad]

On Fri, Apr 2, 2010 at 10:35 AM, Kenneth Gonsalves wrote:

> On Thursday 01 Apr 2010 7:32:37 pm PlaneMad wrote:
> > On Thu, Apr 1, 2010 at 5:45 PM, Kenneth Gonsalves 
> wrote:
> > > landsat is cool - am now able to map the lakes in the Nilgiris with
> > > reasonable
> > > accuracy
> > > --
> >
> > dont forget the lakewalker plugin. one click tracing of water bodies from
> > landsat tiles.
> >
>
> how accurate is landsat? If you look at this link:
> http://www.openstreetmap.org/?lat=11.327&lon=76.6144&zoom=14&layers=B000FTF
>
> the lakes are traced from landsat and you find the road going through the
> lake
> at points. The road is done from gps tracks and is accurate to a meter. And
> even at the closest points to the lake, it is at least 20 meters from the
> lake
> edge even if the lake is full.
> --
> regards
> Kenneth Gonsalves
> Senior Associate
> NRC-FOSS
> http://certificate.nrcfoss.au-kbc.org.in
>
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I had compared landsat lakes in chennai and found the offset error to be
around ~20m max. But in this case it looks like its around 100m. Given the
low resolution, seems understandable.

-- 
http://j.mp/ArunGanesh
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Re: [Talk-in] national parks

[Kenneth Gonsalves]

On Thursday 01 Apr 2010 7:32:37 pm PlaneMad wrote:
> On Thu, Apr 1, 2010 at 5:45 PM, Kenneth Gonsalves  wrote:
> > landsat is cool - am now able to map the lakes in the Nilgiris with
> > reasonable
> > accuracy
> > --
> 
> dont forget the lakewalker plugin. one click tracing of water bodies from
> landsat tiles.
> 

how accurate is landsat? If you look at this link:
http://www.openstreetmap.org/?lat=11.327&lon=76.6144&zoom=14&layers=B000FTF

the lakes are traced from landsat and you find the road going through the lake 
at points. The road is done from gps tracks and is accurate to a meter. And 
even at the closest points to the lake, it is at least 20 meters from the lake 
edge even if the lake is full.
-- 
regards
Kenneth Gonsalves
Senior Associate
NRC-FOSS
http://certificate.nrcfoss.au-kbc.org.in

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Re: [Talk-in] national parks

[PlaneMad]

On Thu, Apr 1, 2010 at 5:45 PM, Kenneth Gonsalves  wrote:

>
> landsat is cool - am now able to map the lakes in the Nilgiris with
> reasonable
> accuracy
> --
>

dont forget the lakewalker plugin. one click tracing of water bodies from
landsat tiles.

-- 
http://j.mp/ArunGanesh
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Re: [Talk-in] national parks

[H.S.Rai]

On Thu, Apr 1, 2010 at 5:45 PM, Kenneth Gonsalves  wrote:
>
> landsat is cool

Unable to get landsat images in JOSM on Ubuntu. able to get Yahoo!,
for landsat it give:

"Exception occurred"

JOSM -> Edit -> Preferences -> WMS has wms url:

http://onearth.jpl.nasa.gov/wms.cgi?request=GetMap&layers=global_mosaic&styles=&format=image/jpeg&;

Can you find what is wrong?

-- 
H.S.Rai

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Re: [Talk-in] national parks

[Kenneth Gonsalves]

On Wednesday 31 Mar 2010 5:36:39 pm PlaneMad wrote:
> I did it using landsat imagery, forest areas shows up with a different
>  shade of pink/green and can be distinguished from regions that had human
>  occupation, which are darker or patchy. I've mapped out all such regions
>  in Tamil Nadu and those in the Mumbai-Pune area. The national park
>  boundaries are approximate and i used the coordinates that were available
>  on wikipedia articles for that.
> 

landsat is cool - am now able to map the lakes in the Nilgiris with reasonable 
accuracy
-- 
regards
Kenneth Gonsalves
Senior Associate
NRC-FOSS
http://certificate.nrcfoss.au-kbc.org.in

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Re: [Talk-in] Tagging roads with median

[Kiran Jonnalagadda]

On Thu, Apr 1, 2010 at 12:23 PM, PlaneMad  wrote:

>
> I have been mapping it as two parallel oneways almost mainly for the
> purpose of routing. I have also found that it makes it much easier to follow
> the road pattern especially at complicated junctions/interchanges (see
> hebbalor
>  hudson
> circle).
> It doesnt make sense to do this for each and every road with a median
> though, but only for the arterial thoroughfares.
>

That makes sense, but we need a way to deal with quirks like the double
traffic lights.

Also, would the relation tags be a useful way to do this?
http://wiki.openstreetmap.org/wiki/Relation:restriction
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Re: [Talk-in] Tagging roads with median

[PlaneMad]

On Mon, Mar 29, 2010 at 5:30 PM, Kiran Jonnalagadda  wrote:

>
> Praveen, I think we should tag as per street conventions and get search
> fixed to work for it.
>
> I noticed another odd bit: many streets with dividers are in the db as two
> parallel one-way roads, resulting in oddities such as this one:
> http://osm.org/go/yy4Z9FN84--
>
> I found this earlier discussion:
> http://lists.openstreetmap.org/pipermail/newbies/2009-August/003447.html
>
> What does the list think as the appropriate way to tag divided roads?
> Parallel ways work for traffic routing algorithms, but are so much more
> work, and don't offer a clean solution for gaps in the divider.
>
>
I have been mapping it as two parallel oneways almost mainly for the purpose
of routing. I have also found that it makes it much easier to follow the
road pattern especially at complicated junctions/interchanges (see
hebbalor
hudson
circle).
It doesnt make sense to do this for each and every road with a median
though, but only for the arterial thoroughfares.


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