Best strategy for polygon search?

Question

I have a fairly simple question. What is the best strategy to do the following scenario? I think this is a very common scenario:

1. I have a several thousands of dataset with polygon/points. Each dataset/record can have multiple polygons.

2. Allow users to draw a polygon and search which datasets fall into that space

3. I have several predefined polygon/areas, that the users can also use/pick to search for datasets.

When the search is done, just show the list of the datasets, display as markers on a map. I'm not worried about this bit because it has been done just with OpenLayers.

My current options (I am new and some of my current options may not even be possible. Please let me know if that is the case) are:

1. Put datasets in PostGIS, set it up in Geoserver. Put predefined polygons straight in geoserver. Use WMS filtering.
2. Put datasets in PostGIS, but not in Geoserver. Put predefined polygons in PostGIS and Geoserver for displaying. Use PostGIS intersection.
3. I've heard from another person that for performance ,it is best to calculate the intersection using a custom app, e.g. Java / other

I'm not sure what is the best in terms of performance and efficiency. Suggestions are very welcomed!

Answer 1

you can use cql or ecql filters.

cql_filter=INTERSECT(the_geom,%20POINT%20(-10.00000%20.000000))

or

BBOX(the_geom, -10, 20, -30, 40)

or

Cross layer filtering, here.

That is, the ability to find in layer A features that have a certain relationship with features in layer B. This can be used, for example, to find all bus stops within a certain distance from a shop, or all coffe shops in a certain city district. Since filter functions are widely supported in GeoServer this cross layer filtering can be applied in SLDs, CQL filters and WFS requests alike.

for wms:

DWITHIN(the_geom, collectGeometries(queryCollection('sf:roads','the_geom','INCLUDE')),
        200, meters)

for wfs:

@Andrea Aime has given an example about wfs request.

beside this geodjango has lots of spatial lookup as you want...

i hope it helps you...

Answer 2

If it's just search that you're looking for you can do a WFS request with a spatial filter of type Contains or Intersects, something like:

<wfs:GetFeature service="WFS" version="1.1.0"
  xmlns:topp="http://www.openplans.org/topp"
  xmlns:wfs="http://www.opengis.net/wfs"
  xmlns="http://www.opengis.net/ogc"
  xmlns:gml="http://www.opengis.net/gml"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.opengis.net/wfs
                      http://schemas.opengis.net/wfs/1.1.0/wfs.xsd">
  <wfs:Query typeName="topp:states">
    <Filter>
      <Intersects>
        <PropertyName>the_geom</PropertyName>
          <gml:Polygon>
            ...
          </gml:Polygon>
        </Intersects>
      </Filter>
  </wfs:Query>
</wfs:GetFeature>

The above will be translated into a native spatial search in PostGIS