[HOT] Fwd: mapping standards

s55447 s55447 at beuth-hochschule.de
Mon Nov 10 11:08:14 UTC 2014

Hello Pierre, hello John!

Thanks a lot for your quick and detailed replys! I did't expect a 
"simple" answer anyway ;-)

Your hint, John, that HOT-mapping is more standardised makes the 
guidelines (http://wiki.openstreetmap.org/wiki/Highway_Tag_Africa) more 
than only a rough orientation for us. And I agree with you, the most 
important tasks to work on is the traffic network and that's what we 
actually concentrating on. We're just trying to figure out how to do it 
"as right as possible". I found conventions that seem to underline the 

"In some situations it is however appropriate to base the tag value on 
the physical attributes of a highway:
- The official classification for the road is not known or easy to 
- The administrative classification for a road does not match the 
physical attributes for some historical reason."

So, is there a general favour for tagging based on physical attributes 
instead of administrative levels? Would a wide frequently used and well 
biult county-level road get a secondary-tag although it belongs to the 
3rd administrative level?

In fact, our work has been initiated by a group of Cameroonians running 
a small non-profit association for setting up connections and provide 
support in terms of research and education. They are helping us 
translating our questions and transfering them to local people they 
know. So we asked about official criteria the government uses for 
classifying their roads and for establishing a network hierarchy. We've 
been told that the guys have already approached the administration and 
are waiting for an answer. What ever this answer might be, we hope that 
some of the criteria we'll get back can be applied in our work based on 
satellite images. But we're still waiting ...

John, you've mentioned a "list of tasks". Where can we find this list? 
Does this list indicate, what features or regions are "under 
contruction"? We found a reasonable amount of "undefined" objects 
(mostly roads) in our area which are not visible in OSM or the 
iD-Editor. Is there someone working on these objects? What shall we do 
at locations where we know that these exist? I'm afraid of finally 
ending up either with an inhomogeneous, incomplete mapping result or 
with objects being mapped twice after the "undefined" showed up again.

So far for now! Thanks again for your support! kamak

Am 2014-11-09 19:49, schrieb john:
> I'm currently mapping #684 - Polio outbreak and Ebola preparedness,
> Meiganga, Cameroon and I must confess I have questions about the 
> project.
> I can understand French especially a European or African accent so the
> video was useful to some extent.
> To me HOT is different to normal OSM.  In normal OSM people basically 
> do
> their own thing.  Sometimes they use "standard" tags but there is a 
> wide
> range and style of tagging.
> HOT prepares maps for a particular target audience so to my mind takes 
> a
> more standarised approach.
> What I haven't seen is a list of requirements.
> There is a list of tasks but that isn't the same as a list of 
> requirements.
> For Meiganga there are thousands of buildings to be mapped.  I 
> understand
> the idea that ideally each building outline shape should be carefully
> mapped but realistically with the JOSM building tool I can approximate 
> the
> building size in two or three seconds.  To carefully trace the outline
> takes me twenty seconds or so.  If I look at some tasks I see someone 
> has
> mapped three buildings then given up.  They are beautifully mapped but 
> when
> there are another 98+ buildings to map in the task and another 180 odd
> tasks to do?  Yes we are using volunteers so their time doesn't cost us
> anything but mapping buildings is tedious and how fast do we want the
> information to be made available and how accurate do we need it?  What
> exactly is the requirement?
> I think for this you need to go back to the AID agencies and the 
> Cameroon
> government cartographers and get them to make a list and set 
> priorities.
> Can we tackle the tasks differently?  The road network and water really
> need to be done first.  It's better to have as few a number of segments 
> in
> a read as possible.  That way when you tag the name you only need do it
> once.  Water, in a task its difficult to see if its a river, ditch or a
> clump of trees sometimes.  From further out you stand a better chance.
> Also if we break the tasks down then the grunts, sorry less skilled
> volunteers, can tick off the task as done when they've mapped all the
> houses and paths.  If they are daunted by the idea that they have to 
> map
> all the "residential and non-residential" buildings and forests before
> marking the task done they maybe reluctant to tick the box and we end 
> up
> with lots of tasks mapped but not ticked as done.
> Then we get to the quality of the map.  It sounds dumb but different
> satellites have different accuracy.  DigitalGlobe’s WorldView-2 is one 
> of
> the better ones.  There was presentation by *Kevin* Bullock on the 
> subject
> at a SOTM US recently but the video seems to have disappeared.  If you 
> can
> find it the relevant bit is 15 mins in for 90 seconds.  If you look at 
> in
> task 684 you'll notice that the Bing imagery and the Mapbox imagery 
> don't
> quite line up.  Some mapping has been carefully done from Bing and some
> from the DigitalGlobe imagery.
> Can we clean the data up?  Interesting question, from a satellite 
> imagery
> I'm unable to tell if a building is residential or not, however many
> buildings mapped from satellite imagery are tagged building=house 
> rather
> than building=yes.  I would suggest that if building=house is tagged 
> from
> satellite imagery this be changed to building=yes by bot but only if 
> its
> the initial tag on the building.
> Some small blobs might be a car or an outhouse.  Perhaps it might be
> worthwhile to scan for a minimum size building?
> If we go back to the idea of requirements again it seems likely that to 
> get
> a better map we need someone on the ground.  worldbicyclerelief.org do
> reasonable bikes for Africa, I'm from a technical background so I like 
> the
> idea of some sort of computing device to enter data on. Smart phone 
> perhaps
> or can we work with one of the local schools?  I assume that Internet
> access is not ideal but text messaging might work.  I'd envisage
> compressing / encoding the information so it fitted into the 
> constraints of
> text messaging to get the updates back.  It would need some programming
> effort on the device and at the other end but there are a large number 
> of
> programmers around OSM.  This may well be already sorted out but as a
> mapper I'd like to think that my efforts were used rather than left 
> waiting
> for someone on the ground to do their bit.  I might even dump some cash
> into a charity that could sort this sort of stuff out and yes I know 
> its
> not as instant as a bag of flour but it is important to have the
> infrastructure in place.
> Cheerio John

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