[HOT] Introduction

Dan S danstowell+osm at gmail.com
Mon Jul 7 08:44:24 UTC 2014


Hi Alex,

Welcome to HOT! I stumbled upon HOT a bit like you did. My personal,
non-authoritative perspective on your questions:

1) Yes, sometimes it's frustratingly difficult with low-res imagery to
know what you can contribute. I would say DEFINITELY carry on mapping
those big waterways you mention. In my experience, when we're trying
to map an unmapped area, having those landmarks in OSM's database
(waterways, major roads, residential areas) really helps future
mappers to have points of reference, even if they are approximate and
need refining later.

2) Re farmlands and forests: I sometimes draw these in, but not often.
I agree with you that it seems helpful to give a rough picture of the
landscape to expect, BUT on the other hand, I think having these
polygons all over can sometimes make the more important jobs harder:
jobs such as checking that every single building has been captured.
And since these landuse polygons are pretty much never requested in
the tasks (apart from landuse=residential which is often a crucial
first step), it seems the locals and the aid organisations don't
particularly need them. So I would suggest don't spend much time on
those.
                  If you see tasks which seem fairly complete, it
might be a better use of your time to get yourself to a point where
you feel confident enough to *validate* other people's completed
squares. It takes a little while to feel confident about being a
validator but we always need more validation effort than we get.

3) Firstly, you should indeed tag the changeset with the actual
imagery you used. But secondly, if you're not careful about which
imagery you use, there's a risk that you might end up tracing from
imagery that is a couple of years old or something like that. My
personal approach would be to try and use the recommended imagery,
since someone has usually put effort in to working out which imagery
is most appropriate. Also, there's usually a conversation on the
mailing list which always gives some clues about what to use.

Hope this helps -
Best
Dan

2014-07-07 9:24 GMT+01:00 Alexander W. Janssen <alexander.janssen at gmail.com>:
> Hi,
>
> I'm new to this list and I wanted to give a shout and say Hello. I'm
> using OSM now for... uh, frankly, I don't remember, but I only started
> mapping a few years ago. I mostly do it in my vacations and create
> GPS-tracks during my hikes. Ever since I can't walk very good any
> more, I started to improve maps in my area - mostly in the suburbs
> where streets are correctly mapped, but houses and their addresses are
> missing.
>
> I just stumbled upon HOT; I immediately liked the idea and started
> working on some Ebola Outbreak tasks.
>
> That's also why I'm writing this email, I have a few questions.
>
> 1) Imagery isn't that good - at least not for most the tasks I was
> randomly assigned too - and I'm having a hard time finding the
> proper... quality expectation. When imagery is bad I try at least
> drawing big waterways (as areas/multipolygons) using Landsat or
> MapBox. I don't quite think that the actual result is that good. What
> is best practice here - do it anyway so that at least basic
> information is available or just leave it alone?
> 2) When I get assigned to a task which looks pretty complete when it
> comes to villages, houses, streets and the such, I draw farmlands and
> forests. From my point of view - when I go to remote areas - I like it
> when the map gives me a basic idea about how the landscape looks like.
> However, the validation process takes longer. Should I continue
> drawing these areas or just skip it?
> 3) Especially regarding the tasks "Ebola Outbreak, Sierra Leone,
> Kailahun district": It says I should comment the changeset with
> "source=DigitalGlobe/Mapbox" - however, that imagery is either non
> existent or not that good - Landsat (and Spot, where available) give
> much better results. In JSOM I generally just say "fetch sources from
> active layers". I guess I'm doing it right...?
>
> Thanks!
> Alex. (user yalla)
>
> --
> The best thing about procrastinating is you can do it NOW and ANYTIME.
>
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