[HOT] HOT OSM Tasking Manager - lots of them

[Nick Allen]

Hi,

I agree that smaller squares are generally a better idea - something 
that an experienced mapper will finish in 10 minutes will generally take 
a whole mapathon for someone new.

But - couple of notes of caution;

Highways & other longer features.  For a straight road, you place a node 
at each end of the straight & then at intervals around the curve. If 
your two nodes of the straight section are each outside your square then 
nothing is downloaded when you download via the Tasking Manager. When 
you are mapping your square you look at part of a highway going through 
it, wonder why it hasn't been mapped, and add it in - you don't realise 
it has already been mapped. This is far more likely to happen close to 
the corner of a square where the distances are shorter. Also far more 
likely to be a problem with smaller squares.

landuse=residential boundaries.
If your whole square is within a number of other squares which each have 
the boundary going through it, but yours doesn't because the boundary 
passes through the squares outside yours, you won't realise & will put a 
landuse=residential boundary around the buildings in your square.

Anyone downloading a large area containing what were lots of small 
squares has a lot of work to do deleting duplicate sections of highway 
and concentric areas of landuse=residential.

The most successful mapping projects that I have seen approach the 
mapping of an area in a staged approach - preferably with local mappers 
being heavily involved in the organisation & quality control. The 
process is going to vary according to urgency, skills of the team 
available, and the geography of the area, but roughly speaking you could 
do with;
1. The main roads, rivers & other larger features such as railway lines 
being present - fairly big squares or no squares at all,
2. A project to add residential boundaries & realign any features that 
need it (smaller squares) & when that is finished & validated,
3a. Project for tracing buildings (squares can be very small), - if each 
of these projects is for a smaller district of a bigger town, then - at 
the same time
3b Ground surveys for adding names, districts, etc - if the 3a projects 
were small enough & only released once the previous one is finished then 
the surveys will be easier to plan.

Although we can do a lot with 'remote tracing' we do need to work with 
the teams on the ground, and take the advice of local mappers.

& to repeat myself - for remote mapping I think smaller squares 
generally are a good idea.

Regards

Nick
On 11/12/15 10:55, Andrew Patterson wrote:
> Picking up on Jim Smith's comments about splitting tiles, I agree with 
> the idea of splitting tiles where the task is for buildings only - but 
> if highways of any form are the target for the task, I think splitting 
> makes it less easy.  I find that for full size areas I often need to 
> go into an adjacent tile to make sense of a route I'm following.  
> Sometimes what seems to be reasonably tagged as secondary highway 
> suddenly turns into little more than a track as it approaches the 
> boundary - and then has to be followed further to understand what its 
> status might be
>
>
> Andrew
>
>
>
> -- 
> Andrew Patterson
>
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-- 

Nick

Volunteer 'Tallguy' for 
https://wiki.openstreetmap.org/wiki/Humanitarian_OSM_Team

http://www.openstreetmap.org/user/Tallguy

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