[HOT] Buildings and HOT's reputation in OSM

Phil (The Geek) Wyatt phil at wyatt-family.com
Sat Dec 9 23:28:18 UTC 2017

Hi John,


I have no formal role in HOT, just a casual OSM mapper so all these comments are from that perspective. I have participated in HOT projects via their tasking manager. I am also not a coder but am aware of the process involved in respect of the ID Editor and Tasking Manager development.


I don't think building issues are restricted to HOT projects. Indeed when I first started mapping in my own neighbourhood I didnt really have a clue on how to map buildings but over time I found videos, joined mailing lists, found LearnOSM, found tasking managers across the globe and generally became a better mapper. At each step I learnt more and hopefully became a better mapper. I still don't do any validation as I don't consider myself experienced enough in JOSM and lots of the other validation tools. I have participated in some map roulette challenges.


As you have indicated in previous emails, a building tool in ID may stop some of the issues you mention and from my investigation this is actually underway already (and has been for some time). Any assistance you can provide would be appreciated by everyone involved.


I will try and answer specific points in your email from my personal perspective.


·         I think all buildings should be polygons rather than points. Better to teach people how to map as polygons rather than expect another mapper to replace a point with a polygon at some time in the future (if ever).

·         Incorrectly mapped building - I would always try and correct the error if I had the required skills. If there were many on the tile in a tasking manager project that were poorly mapped I suspect I would invalidate the tile if I could not fix them. I would also expect some details from the validator, maybe with guidance on where good instructions are for splitting the building and maintaining any past history on the object.

·         Likewise for buildings 50% greater than actual - I would do the same as above - guide the mapper on what they have done wrong and lead them to better resources.

·         Buildings mapped twice. I am on a crappy Australian fibre to the node connection that regularly crashes so I save regularly (20 - 30 objects). I dont quite understand your comment that a four hour tile lock limit would eliminate this problem - seems completely wrong to me. I would certainly be saving more frequently than every 4 hours. Maybe a reminder popup, after 100 objects, might be a better solution to ensure folks are regularly saving.

·         I don't agree with the view of HOT that "We are the professionals and we know best". Having lurked on the HOT slack channels I have seen how they size up disasters, deal with local OSM groups and other disaster relief organisations before embarking on projects. Indeed on a few occasions they have not undertaken any projects when the local communities have indicated they have the situation in hand. In those cases they simply offer support if required or use their communication channels to direct mappers to the other task managers (if desired). There are regular references to local OSM groups prior to project commencement.

·         As for what is acceptable mapping for a building. The best we can hope for is improving tools, educating mappers, more validation tools plus willing volunteers (or dare I say it, paid workers) to keep an eye on things and help the community make OSM an always improving product.


Volunteer gathered information is a bit of a dark art at the best of times and many folks/governments are still coming to grips with how it all works and how beneficial it can be. Is it perfect...not really, can it be improved...always. I think the HOT (and other) tasking managers and the ID editor are always improving with better task details, more links to resources etc. I think it's up to all of us to contribute in any way we can and put forward ideas, time, funds or expertise to make things better.


I wasn't aware of the OSMF mailing list so I will join that as well and read up what has been happening.


Cheers - Phil



From: john whelan [mailto:jwhelan0112 at gmail.com] 
Sent: Sunday, December 10, 2017 7:00 AM
To: hot at openstreetmap.org
Subject: [HOT] Buildings and HOT's reputation in OSM


Recently there has been some discussion of HOT's input into OpenStreetMap in the OSMF mailing list.


Perhaps one of the problem areas is mapping that is less than ideal.


Basically HOT mainly maps highways, landuse=residential and buildings.


These shouldn't be difficult to map correctly.


Buildings appear to be the most problematic.


I think we need to think about why we are mapping them.  Is node good enough?  There would be less room for mistakes.


If we need outlines and there good reasons why an outline is more valuable than a node then we need to define what is acceptable.  Or do we even care?  and its the do we even care part that is perceived to be the case by some within OSM and that perception is something we should care about.


>From a validation point of view does it matter if the building is not square?  Is it acceptable to square a building even though we know this will introduce an element of approximation or error.


What should be done with a building=yes that covers more than one building?  Do we expect the validator to map each building or just invalidate the tile?


What should be done when the building mapped is more than 50% larger than the image?  Invalidate the tile?


We are still mapping buildings twice.  I suspect some mappers are not uploading within two hours.  Getting mappers to upload every 30 minutes max would go a long way to reduce this, extending the tile lock to four hours would almost certainly eliminate it.  Recently on high priority project I've seen in the order of a hundred buildings double mapped.  They have been done within the last two weeks so it is an ongoing problem. There is a new tool that detects these so they aren't the problem they once were but someone has to run the tool.


If HOT could support a few more projects that were from the community on the ground rather than the "We are the professionals we know what is best" which appears to be perceived sometimes from the number of projects for the RED Cross or other northern hemisphere charities that might also help the reputation and relationship. 


So two points here on one message first is can HOT's reputation be repaired and I suspect that is longer term problem that will take time and a lot of effort rather than a PR job.


Second would someone care to comment on what is acceptable mapping for a building and what guidelines can we give to validators? 


Thanks John



-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/hot/attachments/20171210/b07a6a6d/attachment.html>

More information about the HOT mailing list