Mumbai

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Zoom level : 11
Latitude : 19.03642
Longitude : 72.85947

Mumbai is a city on the West coast of India

People

OSM people in Mumbai, if you have a wiki user page, put [[Category:Users in Mumbai]] at the bottom, to add yourself to Category:Users in Mumbai

AND Data import

The AND Data has now been imported. This included a lots of streets in the city of Mumbai (much more detail than the rest of their coverage of India or China)


AND data cleanup

Some general observations:

The data seems to have a lot of missing street names. Looking at Yahoo! Aerial Imagery many of the streets appear misplaced too. So there is still plenty of improvement work and surveying effort required.

There seems to be an offset mispositioning of the data, compared with Yahoo Aerial imagery. But its not clear whether this is inaccurate AND data, or inaccurate Yahoo imagery. The offset can be seen clearly the crescent shaped road network here. The data is too far South, or the imagery is too far North. It's more likely that the data is too far South, but we could do with some GPS surveying to confirm. Also is this uniform across all the streets data? The 'Who Moved Mumbai?' mailing list discussion has independently raised this issue.

The AND data included an accurate tracing around the coastline. More accurate than the PGS data. Initially both were present. But the AND has now been deleted. It was in fact tagged as a very long place=city closed way. In most places it was better than the PGS data. But with exceptions (AND data showed some land reclamation areas incorrectly so must be quite old. Also the PGS data traces around some concrete piers/harbours, which is nice detail to keep) The most confusing thing about the AND data (which is now deleted), is that it matched the Yahoo imagery perfectly. How can this match, but the street data have such an offset? Weird.

Datasets

Summary of current data sets available in Mumbai (from User:Mikel's mailing list post)

  • 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 accuracy.
  • The Mumbai Freemap data ( http://mumbai.freemap.in/ ) 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 from the 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.

Action plan

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 (via WMSPlugin)
  2. Write conversion scripts for the Shapefiles into OSM. Mikel suggests 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 throw 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 here on the OSM wiki.

Past Events

GNU/Linux User Group, Mumbai Sprint

The GNU/Linux User Group, Mumbai did a mapping sprint in September 2008. Some details on their website

Free Map India 2008 Workshop

There was a "Free Map India Workshop" on February 7-8 2008 in Mumbai. This appears to have been attended by more than 20 people

See Also