[OSM-dev] GeoRSS layer with support for bounding boxes

Nick Whitelegg nick at hogweed.org
Tue Nov 28 00:58:58 GMT 2006

As a follow up to posts made in the OSM dev list, I've developed a prototype 
of a possible OpenLayers "GeoRSS2" layer at


It's heavily based on the main OpenLayers GeoRSS layer but allows bounding box 
retrieval. The constructor no longer automatically fetches GeoRSS features 
from the whole world; instead, GeoRSS features are fetched on demand from the 
load() function which takes a bounds as a parameter.

There are also some functions to map <georss:featuretypetag> values to icons, 
allowing use of custom icons for different feature types.

The code still needs tidying up  - in particular it uses OL 2.1 class 
conventions at the moment, due to the OpenLayers in OSM using that version 
primarily. Also some additional error checking is required at one or two 
places to make it more robust.

Also (and I'm not sure if there are plans to do this in openlayers) the 
GeoRSS2 layer currently converts the lat/lon back to another coordinate 
system (e.g the LikeGoogle coordinate system in OSM) via a global "converter" 
object. Clearly this isn't a particularly good way of doing things but is 
there/are there plans for an OL mechanism for superimposing layers with 
different coordinate systems (e.g. georss using lat/lon and OSM using 

Despite these issues I thought I'd mention it to both dev lists for 
feedback/comments. Would something like this be useful for OL itself as well 
as OSM? Example app using it is at www.free-map.org.uk.


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