[HOT] Buildings and HOT's reputation in OSM

Phil (The Geek) Wyatt phil at wyatt-family.com
Sun Dec 10 00:35:21 UTC 2017

Hi John,


Seems to be a few new issues here but I will have a go at them.


·         I have never been to a mapathon so can't comment on anything to do with them

·         As I understand it, Missing Maps is a different organisation that just uses the HOT tasking manager. Their general mandate seems to be to work with local communities. If they are not, then you probably need to take that up with them (or their participating organisations). I have only worked on their projects via the HOT tasking manager

·         Do you have coding experience that can help with the ID building tool?

·         I still think some alert to save frequently (regardless of tile lock time) would be a better solution than extending tile lock time. That might simply mean that more objects have been mapped over a longer period and the problem compounds.

·         Correcting buildings when validating/shortage of validators? OK if this is unlikely to be the solution then we are back to better tools for initial digitising. Can you help with coding?

·         Wasn't aware of any scoring for validated tiles.


Cheers - Phil


From: john whelan [mailto:jwhelan0112 at gmail.com] 
Sent: Sunday, December 10, 2017 11:07 AM
To: Phil (The Geek) Wyatt
Cc: hot at openstreetmap.org
Subject: Re: [HOT] Buildings and HOT's reputation in OSM


I think the London mapperthons expect 30% of their attendees to return.  So unfortunately 50% can be expected to be "disposable" mappers and they don't search out the information as you do.  If we can keep their interest a bit longer they make fewer mistakes.  So one thing might be to see what we can do to help them return more than once.


There are two sides to HOT, one is the disaster side and I think that side needs the very organised approach to get things done quickly.  The other side is the "missing maps" side and that is where I think we could do better in involving the locals. Generally speaking mappers feel more commitment and involvement mapping locally.  There are some projects run out of Africa and its interesting to see the project managers concerned develop their skill sets over time. The first projects can be really not well thought out but they learn by experience.  OSM in general likes to see local mappers making decisions about imports etc.  Unless we can develop the mapping skills of the locals they aren't going to feel involved and I think that is important.  It's when you see the cafes and other POIs sneaking on to the map that you can be reasonably certain that there are locals getting involved and that is where HOT can get a few brownie points and at the moment I think it needs every one it can get.  This is politics with a small p.


New mappers first time mapping using iD for buildings you might be lucky to see twenty buildings.  Give them a building_tool and you'll get a lot more out of them.  When they map the tile is locked for two hours.  At the end of that time the tile becomes available again to be mapped.  The first mapper may not have uploaded their buildings.  A second mapper now maps the same tile and when they both upload that is when I think we get the double mapping which is a waste of mapper time and not only that but it screws up calculations about how many buildings there are.  With a four hour lock we stand a much better chance that two mappers will not map the same tile at the same time.  Even uploading every thirty minutes would reduce the number of double mappings.


Correcting buildings when validating?  It takes about three times longer to correct a badly mapped building than it does to map it from scratch with JOSM and the building_tool.  In Nepal 70% of the mappers mapped once.  Their building mapping was exceptionally poor.  When faced with large numbers of poorly mapped buildings it seems difficult to find validators who are motivated enough to go in and fix the problems.  I'm not one of them.  If the mappers are only going to map once any feedback will be ignored.  We know that giving feedback within 24 hrs motivates mappers and catches early errors so we get better quality work but we don't have the validators available to do this.  Validation works best if its done at the start of a project as the project progresses.  Validating three month old work is much more work, bad habits will have set in.  Instead of problem avoid its problem correct and that takes more validation effort.


TM3 hopefully will improve this by giving a score for tiles validated. 


Cheerio John


On 9 December 2017 at 18:28, Phil (The Geek) Wyatt <phil at wyatt-family.com> wrote:

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




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