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The shapefiles I'm concerned with can be found here, though I'm sure this could apply to any shapefile using coordinates based on state plane coordinates:

http://dor.wa.gov/content/FindTaxesAndRates/stshpdownloads.aspx

I'm currently using GeoTools, a java toolkit designed for reading in GIS shapefiles like these and displaying information about them. I am able to iterate through the file and display the polygons associated with each tax jurisdiction, but here's an example line of output:

Seattle|0.096|MULTIPOLYGON(((1157963.4622609913 862693.0463841558, 
1157982.575083658 862880.4607074857, 1158623.4100880772 
864826.6100303978, ... )))

Based on my research, these coordinates don't seem to line up with any of the typical coordinate systems. I'm expecting that they are derived from a coordinate system known as State Plane Coordinates, but currently don't seem to be in the right format even for those. I was hoping someone might know where these values come from and if there is a way to get GeoTools to output them in a more standardized Latitude/Longitude format.

Ian Turton
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Eric
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    If I rember it right, shapefiles store the projection with them. If you can get the projection from the file or the projection's `EPSG`-code (a global identifier for projections), you automatically know how to process the coordinates. – vatbub Aug 17 '17 at 00:56
  • Look at the crs tutorial on geotools.org and you will see how to do this – Ian Turton Aug 18 '17 at 12:39

1 Answers1

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I just downloaded the most recent shapefile from the site and put them into ArcGIS and it says the following:

Data Type:  Shapefile Feature Class 
Shapefile:  C:\Users\(...)\Downloads\Cities_17Q3\Cities_17Q3.shp
Geometry Type:  Polygon
Coordinates have Z values:  No 
Coordinates have measures:  No 

Projected Coordinate System:    NAD_1983_HARN_StatePlane_Washington_South_FIPS_4602_Feet
Projection: Lambert_Conformal_Conic
False_Easting:  1640416,66666667
False_Northing: 0,00000000
Central_Meridian:   -120,50000000
Standard_Parallel_1:    45,83333333
Standard_Parallel_2:    47,33333333
Latitude_Of_Origin: 45,33333333
Linear Unit:    Foot_US

Geographic Coordinate System:   GCS_North_American_1983_HARN
Datum:  D_North_American_1983_HARN
Prime Meridian:     Greenwich
Angular Unit:   Degree

Also, the polygon for seattle seems to visually line up:

enter image description here

This means that you are using the GCS_North_American_1983_HARN coordinate system with the Lambert_Conformal_Conic projection

vatbub
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