Washington landuse import
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- More complete coverage of the "landuse" tag, specifically landuse=residential. Initially starting with the city of Kenmore and potentially expanding to King County.
- King County GIS  , specifically the "Property" dataset
- Each parcel in the property dataset as a "PRESENTUSE" field (aka what is this parcel presently used for). The possible values are enumerated here : 
- Initially I am focused on correctly marking areas as landuse=residential
- The following values from the input dataset will be mapped to landuse=residential
|Code||Description||Example Parcel (todo)|
|2||Single family (residential use / zone)|
|16||Apartment (Mixed use)|
|25||Condominium (Mixed use)|
|38||Mobile home park|
|48||Condominium (Mobile Home Park)|
|342||Fraternity / Sorority House|
- Other values to consider for potentially being residential
|6||Single family (C/I Zone)|
|9||Single family (C/I use)|
|300||Vacant (Single-family)||"Single family" seems misleading here. This is used for various parcels without anything built on them, including Parks.|
Data Manipulation for use in OSM
- People have different opinions about how landuse areas should be mapped. How big should each polygon be? Should they cross roads (only small residential roads maybe)? If not crossing a road should it extend to the road centerline or stop at the edge of the road?
- I plan to combine neighboring parcels that are both landuse=residential to form larger polygons where possible. If I can come up with a good solution for automating the process of allowing these residential polygons to cross small roads (highway=residential ?) then I'll do it (as this will result in a smaller/simpler dataset). Otherwise I'll just only do the neighboring parcel merging and therefore not have the resulting areas cross any roads.
- The polygons from the King County GIS are more detailed than is necessary for OSM. I will simplify the resulting polygons to reduce the number of nodes.
Handling existing OSM data (todo)
- Exclude the area from the import if it overlaps with existing landuse=* tags or non-residential amenities? Maybe replace existing unnamed landuse=residential areas that overlap with the imported ones, but don't import if it overlaps with landuse=[anything except residential] ?
- Using some custom java code for parsing kml (todo replace with an existing library)
- Currently using JTS Topology Suite (Java) 
- CascadedPolygonUnion class for merging the adjacent polygons
- TopologyPreservingSimplifier for simplifying the resulting polygons
- todo : how to download osm data and translate to JTS polygons
- todo : JTS Polygon -> OSM XML ?
- osm xml -> ... upload somehow ...
Results so far
- Process King County file (600k+ parcels)
- Filter to Kenmore residential parcels (~6426 of them)
- kml->JTS polygons (10 of them failed due to being invalid polygons, havent looked at details)
- After merging the 6000+ parcels it results in 353 areas, a few of which have holes (OSM multipolygon)