[Imports] Questions about DC import plan

Mikel Maron mikel.maron at gmail.com
Thu Aug 7 13:22:34 UTC 2014


> "Will this be taken care of in a separate process that I am unaware of?"   No plans for that at this time.  

But we (DC OSM community) can start thinking about it. Was decided that this after this first "easy" import pass, would look at this harder conflation import later.
 
* Mikel Maron * +14152835207 @mikel s:mikelmaron


On Thursday, August 7, 2014 8:19 AM, David Jackson (OCTO) <davidy.jackson at dc.gov> wrote:
 

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>Brandon,
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>To answer your solid questions.
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>1) " Are these chunks empty because there was found to be no difference from what already existed in OSM from previous imports? "
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>No. There are many differences between existing building / address data in OSM and what is being loaded. Examples included have buildings tagged with addresses,  geometry of data among others.
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>2) "Why was the decision made to use the tasking manager to conduct a partial import as opposed to conflating the entire dataset, given that the new import process is adding not only building footprints but footprints+addresses?  "
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>The goal of the project was to 'complete' or fill in (almost 100%) the buildings (with address where they exist) for the rest of DC.  This means over 50,000 buildings.   The decision was made because to do a partial import because it would be much less time intensive.
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>"Will this be taken care of in a separate process that I am unaware of?"   No plans for that at this time.  
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>- David
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>David Jackson   |  GIS Analyst  |  Office of the Chief technology Officer
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>(W) 202.724.5135  |  200 I ST SE,  5TH FL,  Washington, DC 
>davidy.jackson at dc.gov |   Blog:  dcaddresscoordinates.blogspot.com
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>Telework Day: Fri
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>On Wed, Aug 6, 2014 at 4:44 PM, Brandon Knight <bknight430 at gmail.com> wrote:
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>Posting this to the OSM Imports and the MappingDC lists:
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>>I've been reviewing the work by OCTO on DC building/address imports currently being conducted via the tasking manager[1] and I've noticed a few things that raised some questions about this plan.  Excuse me if I don't understand this or if there are obvious answers to these questions.  I'm new here.
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>>From my understanding, the current plan is to import all DC buildings and addresses in areas that were not imported in 2008-10.  Tags were converted, building shapes simplified, and then the tags from MAR points[2] were joined to building footprints[3] when a building was found to contain only one address point, and the point deleted.  Data was then split up into chunks by block group and converted to .osm files. Scripts found in the dcbuildings repo[4]
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>>After loading some of block group chunks using the tasking manager I've found that many are completely empty (0 nodes).  The explanation I was given by OCTO was:
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>>" Many of the chunks created by mapbox did not contain any data, this is due to the fact that these areas already had complete or near complete building / addresses in OSM for that area."
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>>My questions are:
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>>1) Are these chunks empty because there was found to be no difference from what already existed in OSM from previous imports? 
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>>I originally thought that the entire DC dataset would be represented in these chunks. If chunks containing only "diffs" was the plan, I couldn't find a clear description of this or representation in the code.
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>>2) Why was the decision made to use the tasking manager to conduct a partial import as opposed to conflating the entire dataset, given that the new import process is adding not only building footprints but footprints+addresses?  
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>>I found examples of large areas of block groups with previously imported buildings lacking addresses that corresponded to empty chunk files.  I looked at the raw data and these should contain buildings with joined address tags that could be copied to the existing buildings.  Currently there are large swaths of buildings with no addresses.  Will this be taken care of in a separate process that I am unaware of?
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>>I also found previously imported buildings that does not exist in the current dataset (or in any satellite imagery that I could find).  Since this import is semi-automated, wouldn't a comparison of the full dataset allowed for someone to spot this and remove it?
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>>Thanks,
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>>-Brandon
>>@geobrando
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>>[1]http://tasks.openstreetmap.us/job/6
>>[2]http://data.dc.gov/Metadata.aspx?id=190
>>[3]http://data.dc.gov/Metadata.aspx?id=59
>>[4]https://github.com/osmlab/dcbuildings
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