[HOT] Tracing tagged buildings

Travis Driessen travis.driessen at pdx.edu
Tue May 5 17:29:57 UTC 2015


"Mapping an area landuse=residential tightly takes more time than a quick
looser area say 25% larger"

Good call... Perhaps then, tightly mapped Land Use can emerge more
organically out of all the preliminary first response mapping activities
and data that is created in the first waves of action, to be used as a
product by civic organizations and public agencies etc. to support long
term sustainable planning efforts....

Saludos, travis



On Mon, May 4, 2015 at 3:50 PM, john whelan <jwhelan0112 at gmail.com> wrote:

> > John, that’s worrisome. Is it because buildings are oddly shaped or
> people are just being sloppy?
>
> I repeatedly see an area of buildings labeled building=yes rather than
> landuse=residential, typically square buildings are mapped with four nodes
> but an odd shape and typically larger than the building which is why I'm
> keen to see the JOSM building tool being used more.  I also look out for
> area=yes, are they buildings? I've corrected several hundred to
> building=yes.
>
> Mapping an area landuse=residential tightly takes more time than a quick
> looser area say 25% larger but that's more an issue of how much resources
> we have available and how many projects we have in the list.
>
> Cheerio John
>
> On 4 May 2015 at 13:39, Robert Banick <rbanick at gmail.com> wrote:
>
>>
>> Hi Klaus,
>>
>> Quick thoughts:
>>
>> 1) Wow, good catch on the wiki. I think what it means though is that
>> nodes are acceptable *only* if we can’t see the outline. Since we can
>> with our imagery we should draw outlines. In a case where we only had GPS
>> points then maybe yes it would make sense to tag nodes as an interim step.
>>
>> 2) Buildings are so tricky because cultural construction practices change
>> and with them the best mapping approach. I’m sure some of our top mappers
>> could write whole books on the topic. It’s tough to define but clearly more
>> needs to be said about not using nodes.
>>
>> 3) The Building Tools plugin is amazing, glad you found it. My favourite
>> JOSM extension by far.
>>
>> John, that’s worrisome. Is it because buildings are oddly shaped or
>> people are just being sloppy?
>>
>> Cheers,
>> Robert
>>
>>>> Sent from Mailbox <https://www.dropbox.com/mailbox>
>>
>>
>> On Mon, May 4, 2015 at 5:06 PM, Klaus Hartl <k127 at gmx.de> wrote:
>>
>>> Hello Robert,
>>>
>>> thank you for your response!
>>>
>>> Regarding your second remark, which is quite the unemotional and
>>> pragmatic evaluation of my notes that I was hoping to receive, I see that
>>> it makes sense to change my workflow.
>>>
>>> I won’t map any further buildings as nodes then.
>>>
>>>
>>> Since other mappers could face the very same decisions, please let me
>>> point out how I came to my odd decision to map buildings as nodes:
>>>
>>> Whether or not we call a mapper experienced, I don’t see experience as
>>> to know tagging rules by heart. Since these could change over the years,
>>> just like visualization rules do, it does matter how those rules are
>>> recapitulated in case of need. In my case, like I did, I read the *schema
>>> specification for the key building*[1], and nothing more since
>>> attributing *a node is not denoted invalid* there*:*
>>>
>>> *Note about using this tag on nodes : although buildings are better
>>> represented with their footprints (a closed way or a multipolygon
>>> relation), OSM is working by iteration and some areas in the world don't
>>> have good aerial imagery or public datasets offering building footprints.
>>> Therefore, buildings on nodes should be tolerated until better sources are
>>> available.*
>>>
>>>
>>> And that’s where I see the odd and thus a risk of this (anti)pattern to
>>> repeat.
>>>
>>> Maybe we could adjust or refine either the specs or our judgement on
>>> applying these specs in order to arrange this procedure more even.
>>>
>>> Is there any opinion on that?
>>>
>>>
>>> Cheers
>>>
>>> *Klaus / k127*
>>>
>>>
>>>  p.s.: I just took a look at the *Building Tools* Plugin for JOSM[2],
>>> which kind of supersedes my two-pass contribution approach by providing a
>>> neat two-and-a-half-click action for creating a perfect, orthogonal
>>> building shape.
>>>
>>>
>>>
>>>  *References:*
>>>  [1] http://wiki.openstreetmap.org/wiki/Key:building
>>> [2] http://wiki.openstreetmap.org/wiki/JOSM/Plugins/BuildingsTools
>>>
>>>
>>>
>>> Am 04.05.2015 um 14:11 schrieb Robert Banick <rbanick at gmail.com>:
>>>
>>> Hi Klaus,
>>>
>>>  *First of all,* thanks for providing such a measured response to a not
>>> very measured message. I’m sorry you got such a rude message in the first
>>> place and want to assure you that it doesn’t reflect HOT’s attitude, both
>>> stated by the organization and unstated within the community, towards
>>> errors by new contributors. Everyone has to start somewhere and errors are
>>> inevitable.
>>>
>>>  *Secondly*, I do have to agree with the point of the message. The fact
>>> is your iterative work process doesn’t fit with the contribution-validation
>>> process HOT has set up to make it easy for everyone to work together.
>>> There’s no graceful way in the technical tools or HOT’s workflow to reflect
>>> that buildings-as-nodes are a transitional step by you towards perfect
>>> data. Thus it creates the potential for others to waste time “correcting”
>>> what seems like a mistake.
>>>
>>> I can understand how this system would work really well when you’re
>>> managing a task or area by yourself. But HOT tasks are done with others and
>>> the system is designed so that we build on one another’s work. Also
>>> consider that no responding agencies are looking for buildings as nodes and
>>> hence your transitional data adds no value until entered as an area.
>>>
>>>  *Finally*, a gentle reminder to experienced: if you encounter
>>> systematic errors from users, however seemingly basic or disastrous, please
>>> give them the benefit of the doubt with a *nice* message. Inviting new
>>> users to contribute guarantees mistakes, but it creates a lot more value
>>> than harm: we have to accept the mistakes as part of the process. If I was
>>> a new user and read the message above I guarantee I would be scared off
>>> mapping — and that means HOT just lost a potential longtime contributor.
>>>
>>> Best,
>>> Robert
>>>
>>>>>> Sent from Mailbox <https://www.dropbox.com/mailbox>
>>>
>>>
>>> On Mon, May 4, 2015 at 11:14 AM, Klaus Hartl <k127 at gmx.de> wrote:
>>>
>>>> Hi HOT,
>>>>
>>>> with this message I’m not particularly answering the previous one
>>>> rather than intending to jump on that topic due to some misunderstandings I
>>>> got notified by concerned users via private message (which I’ll post here),
>>>> on which a little clarification is needed. If the following issues are
>>>> clarified elsewhere, I’d like to thank you for that notice in advance and
>>>> excuse any double posting.
>>>>
>>>>
>>>> Some OSM mapper wrote to me:
>>>>
>>>>  Hi I'd like to let you know that the Task #658 (
>>>> http://tasks.hotosm.org/project/1018#task/658) is a complete mess
>>>> thanks to you and a few other users. Why don't you read the instructions
>>>> before starting to work on the map? You've entered thousand of buildings as
>>>> nodes, when instruction states that buildings has to be entered as polygons
>>>> and now someone is going to waste precious time in order to correct your
>>>> errors. I hope this was your only mistake. I'm not going to waste any more
>>>> time by writing to you; please, read carefully the instructions BEFORE any
>>>> edit.
>>>>
>>>> Have a nice one Regards
>>>>
>>>>
>>>>
>>>> I’d like to post my reasons to this list so that
>>>>
>>>>    - it can be validated by all and
>>>>    - further misunderstandings can hopefully be avoided
>>>>
>>>>
>>>>
>>>>
>>>> Hello […],
>>>>
>>>> Thank you for your friendly notice and for honoring OSM volunteer work.
>>>>
>>>> You're definitely right proposing to trace buildings as areas.
>>>>
>>>> Hence, I am fully aware that I created information what you might
>>>> consider a lack of quality.
>>>>
>>>>  However, the reasons for registering buildings like I did are these:
>>>>
>>>>
>>>>    1. I was working on an HOT task (in case you don't know, please see
>>>>       [1]). Buildings are not part of the main objective of this task, which is
>>>>       rather to find flat spaces suitable for potential helicoper landings among
>>>>       others.
>>>>       2. Regarding my paradigm of contributing to OSM data more
>>>>       generally, I tend to improve data quality in several iterations, this means
>>>>       to break up the task into various pieces (which of course have to be
>>>>       consistent), if it isn't justifiable to solve the task as an one-off (cf.
>>>>       1.). The first iteration in the given case would be to register buildings
>>>>       as quickly as possible. Technically spoken, in JOSM, I copy one building
>>>>       node and then per instance point the mouse cursor on the right spot while
>>>>       pasting. You're right when you call this far from perfect, but it's
>>>>       something me or others can start from later. And regarding the schema [2],
>>>>       attributing a single node looks fairly valid to me. Tracing the building as
>>>>       an area would therefore be part of the next iteration step since some exact
>>>>       adjustment is required per object, which renders the effort many times
>>>>       higher.
>>>>
>>>>  If you've got any remarks or further questions, please don't hesitate
>>>> to state them.
>>>>
>>>> Cheers and happy mapping
>>>>
>>>> *Klaus / k127*
>>>>
>>>> *References:*
>>>>
>>>>
>>>>    - [1] http://tasks.hotosm.org/project/1026#task/114
>>>>       - [2] http://wiki.openstreetmap.org/wiki/Key:building
>>>>
>>>>
>>>>
>>>>
>>>> Cheers
>>>>
>>>> Klaus / k127
>>>>
>>>>
>>>>
>>>> Am 04.05.2015 um 01:50 schrieb Brad Neuhauser <brad.neuhauser at gmail.com
>>>> >:
>>>>
>>>>
>>>> On Sunday, May 3, 2015, Dan S <danstowell+osm at gmail.com> wrote:
>>>>
>>>>> Hi -
>>>>>
>>>>> 2015-05-03 22:03 GMT+01:00 Phil Allford <pallford at gmail.com>:
>>>>> > 1. Should I delete the single node tag for a house when I trace a
>>>>> building?
>>>>> > JOSM warns of object within object... I left the original tags.
>>>>>
>>>>> Yes, delete it - it's important not to lose any extra tags that might
>>>>> be there, so make sure of that (but in many cases it's just
>>>>> building=yes or whatever).
>>>>>
>>>>> Advanced JOSM users like to merge the old node into one of the new
>>>>> building's nodes, moving the tags from node to way, so that the
>>>>> object's history is "connected". Don't feel obliged to do that if it's
>>>>> tricksy.
>>>>>
>>>>> Probably most new users aren't using Potlatch, but for anyone that is,
>>>> you can convert from node to area and keep all tags by selecting the node,
>>>> then shift-clicking where you want another corner to be.
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>>>>
>>>
>>>
>>
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