Centroid Overlay

http://gisapps.co.union.nc.us/ws/rest/v2/geo_centroidoverlay.ashx

Description

Overlay feature centroids from one PostGIS layer onto another PostGIS layer and return the results.

An example for when you might want to use this service is finding all parcels within a particular subdivision. Since subdivision boundaries are sometimes crudely drawn (sorry) their boundaries are sometimes (always) not topologically coincident with parcels. By geometrically comparing the centroid of the parcel we can be fairly certain of which parcels belong "in" a subdivision.

Service Arguments

PARAMETER DESCRIPTION
from_geotable The geotable that has the feature(s) to overlay. Example: If you want to overlay a parcel on another layer, you would set parcels as the from_geotable.
to_geotable The geotable that has the features you want selected by the selected feature(s) of the from_geotable.
fields Comma delimited list of fields to be returned. Fields from the to_geotable should be given the prefix 't', like t.name, while fields from the from_geotable should have a prefix of 'f', like f.acctno.
parameters SQL where parameters. Parameters for the from_table must have a 'f' prefix, and parameters for the to_table must have a 't' prefix. Example: f.acctno = '11111111'.
format Format for the output (xml, json, or geojson)

Service Output

Service output is entirely dependant upon the fields parameter.

Sample Output

Sample XML Output

	<rows count="1">
	  <row>
	    <column name="sub_name">Brandon Oaks</column>
	    <column name="sub_code">BRAN</column>
	  </row>
	</rows>

Sample JSON Output

	{rows:[
	  {sub_name:"Brandon Oaks",sub_code:"BRAN"}
	]}