[Talk-ca] [Imports] [Import] Ottawa Buildings & Addresses [Statistics Canada project]

[Kevin Farrugia]

Generally the planimetric CAD drawings (what Stewart posted) are/were the
source for most municipal building footprints, from what I've seen in my
experience. In some cases the footprints are still maintained in that
format and exported out for GIS, while in other cases they're now
exclusively maintained in GIS. Ottawa may be doing the latter, which might
explain the mismatch between the two.  I know the latter has
happened/happens at my work.

On Oct 25, 2016 8:54 AM, "James" <james2432 at gmail.com> wrote:

There is also a factual basis in the example Scruss provided:
https://wiki.openstreetmap.org/wiki/File:12.PNG

TD Place(Renovated/New buildings constructed in Summer 2014) is not mapped
in the DWG(scruss said as far back as 2011)
In the newer data it is:
https://wiki.openstreetmap.org/wiki/File:13.PNG

I know this as I am a local mapper.

On Mon, Oct 24, 2016 at 6:52 PM, James <james2432 at gmail.com> wrote:

> I can guarantee that this data is roof level data. While I was examining
> data there were cart returns mapped as outlines. This data was also traced
> via orthophotos
>
> On Oct 24, 2016 6:45 PM, "Christoph Hormann" <chris_hormann at gmx.de> wrote:
>
>> On Monday 24 October 2016, Stewart C. Russell wrote:
>> >
>> > > Could you please clarify what the alleged source of the building
>> > > data to be imported is?
>> >
>> > Yes, as far as I understand it, at least: these data to be imported
>> > were given to a group of OSM contributors by the City of Ottawa. They
>> > have explicit permission to include it in OSM from the City. The only
>> > place you can inspect the data is on the contributors' own hosting
>> > sites, as the city doesn't host it anywhere. Details of the licence
>> > and permissions are on the Ottawa import information page.
>>
>> I would then suggest to contact the person who provided the files for
>> metadata and specifications on those, in particular dates and methods
>> of survey, processing applied, especially coordinate system conversions
>> and specifications on what exactly is contained in it (i.e. what the
>> definition of a building is here and if it's ground footprints or roof
>> outlines).  You also might want to specifically ask regarding the
>> geometry issues i pointed out earlier.
>>
>> You can be pretty sure the original producer of this data set has this
>> information and if there is interest in having this data in OSM they
>> should also be willing to provide such information.
>>
>> In OpenStreetMap we put high importance on knowing and documenting how
>> data is acquired since - as every experienced mapper knows - sources of
>> information can be faulty and misleading.  Just because someone says: I
>> have this data here and you may use it and it mostly looks reasonable
>> and plausible at the first glance does not mean we should throw all our
>> sense for critical evaluation of sources out of the window, especially
>> if you plan to add several hundred thousand new features.
>>
>> > The public 2011 data set is cut into 2×1 km tiles, slicing through
>> > buildings on the border. There are no common attributes which would
>> > allow repair, as the data is packaged in AutoCAD DWG files.
>>
>> This alone should not be a problem since you know the location of the
>> cuts and therefore could dissolve them based on position.
>>
>> The real question is - is there a factual basis for the assumption that
>> the data you intend to import is newer than the data in these files?
>> Note a different level of detail is not necessarily an indication for
>> age or accuracy of the data.
>>
>>
>> --
>> Christoph Hormann
>> http://www.imagico.de/
>>
>> _______________________________________________
>> Imports mailing list
>> Imports at openstreetmap.org
>> https://lists.openstreetmap.org/listinfo/imports
>>
>


-- 
外に遊びに行こう！

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