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<span style="font-family: Arial;"><span style="font-size: 16px;">I
note</span></span><span style="font-size: 16px;"> </span><span
style="font-size: 16px;"><span style="color: rgb(58, 58, 58);
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rgb(255, 255, 255); text-decoration-style: initial;
text-decoration-color: initial; display: inline ! important; float:
none;">in weeklyosm</span></span><span style="font-size: 16px;"> </span><span
style="font-size: 16px;"><span style="color: rgb(58, 58, 58);
font-family: "Open Sans",Helvetica,Arial,sans-serif;
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normal; font-weight: 400; letter-spacing: normal; text-align: left;
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word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color:
rgb(255, 255, 255); text-decoration-style: initial;
text-decoration-color: initial; display: inline ! important; float:
none;">that ngumenawesamson has made some comments about data quality in
HOT mapping.</span></span><span style="font-size: 16px;"><span
style="color: rgb(58, 58, 58); font-family: "Open
Sans",Helvetica,Arial,sans-serif; font-style: normal;
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none;"><br>
<br>
I've just finished going through Ghana and doing a bit of clean up. I
tend to map in Africa these days and often end up cleaning up after HOT
mappers and I've been around a long time. <br>
<br>
I think we need to split the mapping into armchair from imagery and on
the ground.<br>
<br>
A couple of comments on the armchair side.<br>
<br>
First buildings, from imagery realistically I think all you can do is
draw a building and say building=yes. I see untagged building outlines,
I see them labelled house, with levels, I see them labelled as layer -1
etc. The NGOs aren't really interested in knowing exactly where the
building is to the nearest centimeter they're more interested in knowing
it exists so they can estimate population. Adding levels from imagery
just contaminates the map.<br>
<br>
Second highways, realistically in Africa we need to map highways between
settlements or between settlements and a highway and these can be
labelled unclassified. Let the locals sort out any other classification
including paths etc. This allows routing. One highway connection per
settlement at least provides a route to it. Let the locals add more, it
will help them feel as if they own the map.<br>
<br>
Personally I'd ignore paths and tracks going to fields. They tend to
clutter the map and take up limited mapping resources. They only other
highway type I'd map in HOT would be highway=residential.<br>
<br>
It also means that in JOSM you can just draw in the highways without
tags. Then JOSM validation will select them as being untagged. Add
highway unclassified and you're done.<br>
<br>
I think you need to understand a bit about your target audience before
planning your project. Sometime ago I worked with a group of six
American university geography students. Their lecturer gave them the
task of mapping one tile each. I was validating on the project and gave
quite a lot of feedback about four times a day. Only one student
completely mapped a tile and that took two weeks. The others dropped
out after a week. The lecturer's comment was she hadn't realised it was
so complex and wouldn't have asked them to do it if she had realised it
was so much work. None of those six mappers mapped again in OSM.<br>
<br>
The instructions on that project needed to be fleshed out. You needed
to go to other places to find out exactly how something should be tagged
and the project asked for everything to be mapped.<br>
<br>
My expectation is an American University student should have a good
command of English. Realistically HOT Mappers first language will not
be English so instructions need to be simple.<br>
<br>
Also HOT projects tend to appeal to high self monitors, ( think of a
group of people who go out on a Friday night and together do crazy
things because it's fun.) They don't have time or interest to read
boring instructions they just want to map so remove their choices as
much as possible and make the instructions simple such as: <br>
<br>
Raw satellite imagery is accurate to 60 meters. To get better accuracy
we align it to existing buildings etc. However expect the different
imagery to be aligned slightly differently and when you map a building
don't place it across a highway. Put it to the side even if the imagery
says put it in the middle of the highway.<br>
<br>
For buildings I and other experienced mappers running mapathons have
found if you give them JOSM and the buildings_tool plugin you get a lot
more buildings mapped by your mappers and they are more accurately
drawn. It takes two or three mouse clicks using the buildings_tool
compared to five or more in iD. </span><span style="color: rgb(58, 58,
58); font-family: "Open Sans", Helvetica, Arial, sans-serif;
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none;"><span style="color: rgb(58, 58, 58); font-family: "Open
Sans", Helvetica, Arial, sans-serif; font-size: 16px; font-style:
normal; font-variant-ligatures: normal; font-variant-caps: normal;
font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left;
text-indent: 0px; text-transform: none; white-space: normal; widows: 2;
word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color:
rgb(255, 255, 255); text-decoration-thickness: initial;
text-decoration-style: initial; text-decoration-color: initial; display:
inline !important; float: none;">I have yet to see a validator
invalidate a building mapped with this tool. iD gives too many choices
of tags.<br>
<br>
JOSM using Microsoft's OpenJDK is fine and is simple to use for new
mappers. It does take some planning though. Have your mappers install
it before arriving. Yes it takes bandwidth but on a laptop you can set
up the laptop to connect to the internet at off peak hours.<br>
<br>
Bandwidth for a mapathon can be a problem. Technically the image tiles
can be cached on a local server. A Raspberry Pi running SAMBA and using
an SSD works well. However one laptop can be used as a server to the
other machines. I'll leave it to HOT's technical team to sort out the
details and create a set of clear instructions. Just remember JOSM
holds the data locally and it can be uploaded at a later date so
technically you could download the tile beforehand into JOSM, work with
off line imagery and uploaded at a later date. The whole mapathon need
not be connected online which could be useful in places with poor or
expensive internet connections.<br>
<br>
On the ground mapping is different and needs a different approach.<br>
<br>
Cheerio John<br>
<br>
<br>
</span></span><span style="color: rgb(58, 58, 58); font-family:
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