[OHM] Mapping the NY Metro Region's Historic Wetlands

Fri Sep 25 19:48:23 UTC 2015

Jerry –

Thanks for the quick and detailed reply. Watched your video that referenced NYPL’s Map Warper before posting here. And right after I sent this message to OHM, I sent a message to MapTime organizers. Will see where it goes!

The NOAA maps are in Clarke 1661 projections and, while they have points that could be used to rectify, I have been georeferencing the maps in ArcGIS. Is there a benefit to doing the rectification in Map Warper vs ArcGIS, as far as the OHM/OSM workflow? It may be easier to share the georeferenced maps after the fact, than georeferencing natural features in a browser. (NOAA maps<http://nosimagery.noaa.gov/images/shoreline_surveys/survey_scans/NOAA_Shoreline_Survey_Scans.html>)

I really like the OSM Task Manager that HOTOSM has running. It would be nice to be able to feed this into that process and chunk out the tasks to the various universities in the region that would be interested in taking on a part of it. Not sure I have the technical chops to get it up and running, but it sounds like a good way to break this up.

Semi-automated tracing sounds interesting, though the maps are not uniform in style. What are some good resources to look into further? I have stayed away from ArcGIS’s automated tracing, as it is better for roads or very obviously defined polygons. The wetlands are signified not by shading or stroke, but by a kind of grassy icon, which may make automation less tenable.

David – I’ve checked that source, but I need a rather uniform data series that covers a 31-county region as early as possible. Thanks for the tip, though.

Really appreciate the replies, as I start exploring how to open up this process. Would love to have a regional historic wetland map available to the planning community that extends earlier than 1900.

Best,
Sanjay

—

Sanjay Seth | Research Analyst

Regional Plan Association

(917) 546-4327 | rpa.org

From: SK53 <sk53.osm at gmail.com<mailto:sk53.osm at gmail.com>>
Date: Fri, 25 Sep 2015 15:26:47 -0400
To: Sanjay Seth <sanjay at rpa.org<mailto:sanjay at rpa.org>>
Cc: "historic at openstreetmap.org<mailto:historic at openstreetmap.org>" <historic at openstreetmap.org<mailto:historic at openstreetmap.org>>
Subject: Re: [OHM] Mapping the NY Metro Region's Historic Wetlands

Hi Sanjay,

A timely query. We were discussing only on Tuesday about the use-cases for mapping historical ecological data. This example of course reflects lots of them (wetlands as buffers in extreme events; as components of water quality; and in some parts of the world sources of disease).

Again we discussed on Tuesday ideas for getting communities involved. I have been thinking about this over the past few days and realise that the scheme used by Humanitarian mappers, Missing Maps, and the smaller get-togethers under the MapTIme banner both represent models for getting a group of people to map specific things allowing straightforward training, coaching & mentoring. Another, rather different, approach is the Irish Townland mapping project, which involves rectifying 1:25k maps covering Ireland (80,000+ sq km) and drawing 60,000 small administrative units from them.

Currently the OHM community is quite small and many of us have multiple commitments to existing projects and related OSM activities (for instance I am doing some specific things in the context of the townlands project), so I don't think we are a great pool of tracers. The much larger OSM communities do have many more people who are looking for such challenges. I'd perhaps start by seeing if MapTime New York<http://www.meetup.com/Maptime-NYC/> might be interested in giving you a slot.

Now for some of the technical problems/issues:

 *   OHM requires that each tagged object natural=wetland is also marked with a start_date & end_date.
 *   It is generally valuable to use a tag which identifies the apparent as_of date of the wetland (i.e., based on underlying map), this makes querying easier). This also makes it easier to filter data in some editors.
 *   It is easier to map something multiple times in different time periods rather than try & reconcile an object across from many source maps. (At least this is true until one has lots of such things).
 *   Coastlines may create problems. This is because of the OSM way of handling coastlines is inelegant. I do have some ideas about how to approach this, but haven't taken them forward yet: the coastline of the River Plate changed dramatically in the late 19th C so affecting stuff I have done with Buenos Aires).
 *   Use meta tags (source etc.) copiously; they will be the only evidence of someone's interpretation of the sources. Ultimately other info like photos, paintings and documentary evidence may need to be incorporated.

Use of any of the Map Warper websites (NYPL, MapWarper & WikiMedia) for rectification would ensure that warped maps are readily available in the editors, and following the Townlands model can also be crowd-sourced.

It may also be worth looking at semi-automated tracing if the map quality permits such an approach.

HTH,

Jerry Clough

On 25 September 2015 at 19:43, Sanjay Seth <sanjay at rpa.org<mailto:sanjay at rpa.org>> wrote:
Dear OHM Community –

I hope you are all doing well. I’m a researcher at an urban policy think-tank based in NYC. We are looking at long-term coastal adaptation strategies –  and are working to map out the NY metropolitan region’s historic wetlands, which we will use (in addition to projected future wetlands) to inform those strategies.

I’m new to the OHM community, but would like to gauge the interest in taking this on together as a group tracing effort. I have hundreds of historic maps from NOAA, starting from 1830’s onward, that would be relatively straightforward to trace, once they were georeferenced. We’re in the process of georefererencing the lot right now. I just don’t have the people-power to trace out thousands of wetlands on my own.

If this sounds like a project you are interested in – or want to just hear more about – let me know. Thanks and feel free to get in touch at sanjay at rpa.org<mailto:sanjay at rpa.org> or (917) 546-4327<tel:%28917%29%20546-4327>.

Best wishes,
Sanjay

—

Sanjay Seth | Research Analyst

Regional Plan Association

(917) 546-4327<tel:%28917%29%20546-4327> | rpa.org<http://rpa.org>

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