[OSM-talk] who moved Mumbai?

Sun Jul 6 09:27:41 BST 2008

Re: Need #1, I just tried this and can quantify the main problem.

The Mumbai Freemap WMS does not seem to be able to use the SRS tag to return
requests in EPSG:4326, which the JOSM WMS plugin expects. It is currently
returning requests in EPSG:32643.

Alternatively, the JOSM WMS plugin could be made to make requests in other
coordinate systems...

- Beau

On Sat, Jul 5, 2008 at 10:26 PM, Mikel Maron <mikel_maron at yahoo.com> wrote:

> Hi
>
> Let me see if I can summarize the current data sets available in Mumbai.
>
> * In February, Martijn imported AND data for India, including great detail
> over Mumbai. However, when examining the data post-import with locals, we
> discovered there was no consistent offset on the data .. there were a large
> number of inconsistencies and errors. Consulting with AND, we learned that
> Mumbai data was largely a side project of AND employees of untraced origin.
> It's likely this data was created without much regard for geographic or
> feature accuracty.
>
> * The Mumbai Freemap data was prepared for the web a couple years ago. That
> data is available as a WMS, though there are currently some unknown issues
> with incorporating that WMS server into JOSM.
>
> * There is now new data available fromthe Maharashtra Dept of Public Works,
> including quite a few data layers. (Maharashtra is the India state in which
> Mumbai is situated). That data is stored in some funky Shapefiles.
>
>
> The question is where to go from here. Technically there are two main
> needs. Can anyone volunteer a little time on...
>
> 1) Get the Freemap server serving WMS requests to JOSM correctly.
> 2) Write conversion scripts for the Shapefiles into OSM. My thinking is
> that a ruby script, using osmlib and ruby-shapefile is the most
> straightforward way to go.
>
>
> With these technical problems passed, we'll have three data sets to work
> with and compare. JOSM can handle this, though it might through up some
> usability issues with such large data sets. We may discover that parts of
> AND Mumbai are so jumbled that it's better to clear the slate and start
> fresh by importing MDPW data, or tracing Freemap. I don't think all of
> Mumbai will have this problem -- the older parts of Mumbai are likely to be
> more accurate. Locals will need to look at this area by area, and make
> judgements, and the whole effort organizing as a WikiProject Mumbai on the
> OSM wiki.
>
> Mikel
>
>
> **
> ----- Original Message ----
> From: Shekhar Krishnan <shekhar at crit.org.in>
> To: OSM Talk <talk at openstreetmap.org>
> Sent: Saturday, July 5, 2008 2:32:02 PM
> Subject: Re: [OSM-talk] who moved Mumbai?
>
> Since someone mentioned the Mumbai Freemap [1] into OSM, I thought I would
> finally introduce myself to the list. I am coordinator of the project, which
> was developed in 2005-2006 to showcase the kind of geo-data being collected
> by volunteers in Mumbai's architect and activist communities connected to
> CRIT (Collective Research Initiatives Trust) [2].
>
> The data itself is poorly formed, having been originally drawn in AutoCAD
> without geographic attributes and retrospectively warped into shape files
> from sets of disconnected lines and attribute tables [3]. In our community
> mapping project, we now hope to merge our base layers into OSM and train
> groups in JOSM to detail particular areas, which we can use as the basis for
> projects on public spaces, community housing and heritage conservation in
> Mumbai.
>
> For some time now we have wanted to contribute this data to OSM, and we now
> have devoted funds from UNDP [4] which we plan to use in support of OSM as
> an infrastructure for our research and design practice. Earlier this year
> Mikel Maron and Schuyler Erle organised a series of Freemap/OSM  workshops
> [5] which seeded new communities in cities across India, and in Mumbai
> generated significant interest.
>
> We think that the existing Mumbai Freemap is mostly useful as a backdrop
> (WMS) against which new nodes and relations need to be traced and tagged
> within OSM, and we are determined to migrate our vector data into OSM in
> stages over the next few months. Chris Schmidt wrote this script [6] to
> migrate MassGIS shape files into OSM.
>
> Any suggestions on how best to approach this SHP to OSM migration and the
> wider goals of our project are most welcome!
>
> Best,
>
>
> Shekhar
>
> [1] http://mumbai.freemap.in
> [2] http://crit.org.in
> [3] http://wiki.freemap.in/moin.cgi/MumbaiFreeMapDatabase
> [4] http://www.apdip.net/projects/ictrnd/2005/l43-in/
> [5] http://wiki.freemap.in/moin.cgi/FreeMapIndia2008
> [6] http://boston.freemap.in/osm/files/mgis_to_osm.py
>
>
>
> 2008/7/5 Nathan Vander Wilt <nate-lists at calftrail.com>:
>
>> On Jul 5, 2008, at 1:01 AM, Kenneth Gonsalves wrote:
>> > On 05-Jul-08, at 3:24 AM, Frederik Ramm wrote
>> >>
>> >>> everything is AND and everything is consistently out of place to
>> >>> the  southeast with the same offset - is there any way to
>> >>> programmatically  change this?
>> >>
>> >> I have a script that I could use for this task if people want.
>> >> Obviously I'd need to know exactly what to move and by what amount...
>> >
>> > cool - will measure the offset and revert
>>
>> Are you sure this isn't a coordinate system datum issue? If the AND
>> data uses a different datum than WGS-84, it may be more than just a
>> simple offset for all vertices that you need. There are several open
>> source programs available for converting from one datum to another.
>> What datum is the original AND data in?
>>
>> thanks,
>> -natevw
>>
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>>
>
>
>
> --
>
> Shekhar Krishnan
> 9 Supriya, 2nd Floor
> Plot 709, Parsee Colony Road no.4
> Dadar, Mumbai 400014
> India
> 
> http://web.mit.edu/shekhar
> http://heptanesia.net
> http://bombayology.net
>
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