[Talk-GB] OSM University of Liverpool exercise (or 200 free(ish) volunteers)

SK53 sk53.osm at gmail.com
Thu Nov 27 16:35:54 UTC 2014

I agree with Matthijs that this is a nice initiative, and I'm very pleased
that you have started this discussion.

I am not a Merseysider myself, but I lots of family in the area. Although I
visit fairly frequently I rarely get the opportunity to map, but can form a
general impression about the local level of mapping detail.

My general impression of mapping both on the Wirral, and in Liverpool
proper, is that what the area seriously lacks is some
decent on the ground surveys. For instance the roads located here
<http://www.openstreetmap.org/#map=17/53.42623/-2.96033> in Everton have
undergone extensive re-development since the available aerial photos
(disclaimer, I believe some of the houses which have been demolished were
built by my great-grandfather). An excellent resource, although not
suitable for direct use in OSM, is the Flickr photos by Russ Oakes
(Liverpool Suburbia) https://www.flickr.com/photos/liverpoolsuburbia/. (I
have in the past briefly discussed the use of his photos for OSM, but have
not followed this (see for example this discussion <https://flic.kr/p/PPGqD>).
He may be amenable to use of his photos for his project.

I think digitising buildings in Central Liverpool is quite difficult, but
the suburbs are OK (as demonstrated by recent work on The Wirral): I
recently added a number of food outlets based on Food Hygiene Open Data,
and better building outlines would certainly help for this. In Nottingham
we have found that really we also need street-level photos to assist in
correct interpretation of the aerial images. The biggest caveat is ensuring
that any building outlines added are actually still extant.

I don't know to what extent you will want to assess individual students
with this work, but here are some suggestions for things which might work:

   - Get individual students to create Mapillary
   for streets in the city centre (I imagine Liverpool One is not suitable as
   most shopping centres prevent photography). Experience shows that Sunday
   mornings are the optimal time to collect such photo sequences: mainly
   because there are fewer people about.
   - Use the Mapillary sequences to map POIs (mainly shops, restaurants and
   pubs). (The existing sequences can be used to trial this approach).
   - Add address data from Food Hygiene Open Data
   <http://ratings.food.gov.uk/open-data/en-GB> where available
   - Use Mapillary sequences and the available aerial imagery to create
   building outlines. (Other sources such as Geograph photos can also assist).

Tasking can be done by individual street or a set of postcodes
(particularly useful if cross-referenced to the FHRS Open Data). The
advantage of using Mapillary is that this provides additional sources of
information about Liverpool which can also be used by other mappers.

I have metrics from my own surveys of this type, but would expect a
shopping street 200 metres long would occupy a student for perhaps a couple
of hours (certainly my first shopping street, Floral Street in London, took
quite a long time). In general data collection is much faster than data
entry (a ratio of 1:3 or 1:5 for experienced mappers probably more for
inexperienced mappers).

The reason I suggest this approach is that unlike many OSM tasks it can be
fairly readily bounded (all shops in a given postcode is usually < 40), and
introduces a wider range of mapping techniques other than digitising
buildings (as well as ontology issues, which might make for interesting
classroom discussion).

Of course I would like to see more work done in the suburbs, but suspect
that this would be impractical to manage for a large student assignment.
Getting students to add their local knowledge using the OSM Note facility
may also be beneficial.

The key problem with OSM assignments is that mastering the editors may take
most of the time allowed for the practical. There are a number of useful
presentations on using OSM in a variety of teaching environments: I dont
have a list to hand, but I think most SotM-US conferences have featured at
least one.

Hope these comments might be of some use.

Jerry Clough

On 27 November 2014 at 11:09, Matthijs Melissen <info at matthijsmelissen.nl>

> On 27 November 2014 at 13:50, Nick Bearman <n.bearman at liverpool.ac.uk>
> wrote:
> > I'm looking for someone who has completed something similar in the past
> and
> > has any recommendation on how to do this most effectively, and what
> areas in
> > Liverpool would benefit most from the students contribution. Currently,
> > giving the time available to the students, I would be thinking of a
> > desk-based digitisation exercise, but this can be flexible. I've already
> > contacted John McKerrell but I'm interested to talk to other mappers in
> > Liverpool that can suggest areas that need the most attention and/or who
> > might like to be involved.
> Nice initiative! I think adding building outlines is quite useful, and
> has relatively low risk that the students break things (an important
> consideration, especially with such a large group). West of the
> Mersey, most buildings are added, but East of the Mersey, there are
> hardly any building outlines yet. I think with such a large group, you
> should be able to cover the entire city even if you give everyone a
> tiny area to do. Probably best to split the city into several 'tasks'
> yourself to prevent overlap?
> Make sure that your students have a reference to your contact details
> somewhere, in their profile or changeset comment perhaps, so that
> mappers can contact you if something goes wrong.
> I am not a local mapper in Liverpool, make sure to also get support /
> approval from the locals.
> -- Matthijs
> _______________________________________________
> Talk-GB mailing list
> Talk-GB at openstreetmap.org
> https://lists.openstreetmap.org/listinfo/talk-gb
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/talk-gb/attachments/20141127/a9175286/attachment.html>

More information about the Talk-GB mailing list