[talk-ph] Luzon Coastline

maning sambale emmanuel.sambale at gmail.com
Fri Feb 20 09:10:29 GMT 2009


Just had a look at the area and coastlines seems sane.  AFAIK,
coastline are not rendered regularly.   Rendering of coastlines comes
from shapefiles based on OSM and not directly from the OSM dbase.

On another note, I browsed around the general area Subic, Castillejos,
San Narciso, San Felipe, Olongapo.  It seems a lot of data are added
the past weeks.  Along with a whole lot of errors:
unclosed areas
overlapping highways
unconnected and duplicate nodes
missing nodes on intersections

(Didn't touch anything today, though)

I'm curious (and suspicious) about the data source.  I see no yahoo
imagery, not even a public GPX trace.  This issue has been discussed
before:
http://lists.openstreetmap.org/pipermail/talk-ph/2009-January/000312.html
And I did flagged the attention of one mapper.

As I see no "proof of authenticity" I am again questioning these
edits.  I know it's a wiki.  May I ask other members of the group to
contact the respective mappers?  I am not discounting the fact that
local knowledge maybe the source (ianlopez did great in San Pablo only
with landsat and local knowledge), but can we discuss this first with
the mappers? And hopefully avoid edit war.


On Fri, Feb 20, 2009 at 4:40 PM, Ed Garcia <eppgarcia at gmail.com> wrote:
>
> I also tried to "trace" that coastline section too a few days ago via JOSM
> and was looking for possibility of "unmerged coastline nodes" somewhere.
> Found none.
>
> That section that went AWOL could be it.  Can't wait for Wednesday.
>
> Thanks Jim!
> :>)
>
> On Fri, Feb 20, 2009 at 4:20 PM, Jim Morgan <jim at datalude.com> wrote:
>>
>> I've been trying to figure out the Luzon coastline around Zambales, as its
>> driving me nuts. Personally I think it looks terribly offputting to see such
>> a glaring error, especially as we're seeing some new members recently.
>>
>> So I looked at the coastline checker here,
>>
>>  http://tile.openstreetmap.nl/coastlines.html?zoom=9&lat=15.1027&lon=120.35419&layers=B00T
>>
>> and, using the notes here
>>        http://wiki.openstreetmap.org/index.php/Coastline_error_checker
>>
>> investigated a few of the Big Red Dots.
>>
>> From looking at them in JOSM, the Big Red Dots seem to be at areas where
>> the coastline is split into different sections. The sections have the same
>> tags i.e.
>>  layer=-1
>>  name=Luzon
>>  natural=coastline
>> and the direction is correct -- wet on the right.
>> But they have different description and Notes fields.
>>
>> Is this the problem then? That the notes fields are different and that
>> this has somehow made the renderer unable to recognise that they are the
>> same coastline? I can't imagine that it is ... Or do the coastline segments
>> need to be joined together?
>>
>> I understand that the islands outlined in red are only being flagged as
>> wrong because they are currently "on land" so those will disappear when we
>> get the coast corrected.
>>
>> Possibly related to this, I noticed that a section of the coastline had
>> gone AWOL around Subic airport, and actually cut across the runway, so I put
>> in a temporary section of coastline so that the coast goes outside the
>> airport. Its very approximate at the moment, but at least it is
>> topologically sound.
>>
>> Maybe I'll wait and see if this glitch was causing all the problems. I'm
>> crossing my fingers that I haven't made things worse, but I thought I'd
>> mention what I've been doing here, so that if the sea suddenly drains away
>> from the entire Asian subcontinent, you'll know where to point the fingers
>> of blame (and where to go to start fixing things ... .).
>>
>> If anyone else has any bright ideas on how to fix this coastline, please
>> help me out here. I'm a little out of my depth (no pun intended), but its
>> been broken for several weeks.
>>
>> Jim
>>
>>
>>
>> --
>>   datalude: information security
>>   e: jim at datalude.com
>>   Philippines: +63 2 403 1311 / mob: +63 920 912 5830
>>   Hong Kong: +852 9100 7586
>>   w: http://www.datalude.com/
>>
>> _______________________________________________
>> talk-ph mailing list
>> talk-ph at openstreetmap.org
>> http://lists.openstreetmap.org/listinfo/talk-ph
>
>
>
> --
> website administrator:
> - www.waypoints.ph
> - reeflife.eppgarcia.com
>
> PADI Divemaster #491048
>
> _______________________________________________
> talk-ph mailing list
> talk-ph at openstreetmap.org
> http://lists.openstreetmap.org/listinfo/talk-ph
>
>



-- 
cheers,
maning
------------------------------------------------------
"Freedom is still the most radical idea of all" -N.Branden
wiki: http://esambale.wikispaces.com/
blog: http://epsg4253.wordpress.com/
------------------------------------------------------




More information about the talk-ph mailing list