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

Mikel Maron mikel_maron at yahoo.com
Tue Nov 28 15:43:59 GMT 2006


Very nice.This just about implements WFS Basic, which is more or less GeoRSS retrieved with a bbox argument.

I could see this being a useful update to http://brainoff.com/osm/change/, for monitoring change over a certain area.
The worldkit monitor only retrieves changes for the entire world, and is only using landsat.

-Mikel

----- Original Message ----
From: Nick Whitelegg <nick at hogweed.org>
To: dev at openstreetmap.org
Cc: dev at openlayers.org
Sent: Tuesday, November 28, 2006 12:58:58 AM
Subject: [OSM-dev] GeoRSS layer with support for bounding boxes


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

http://www.free-map.org.uk/javascript/GeoRSS2.js

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 
LikeGoogle)?

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.

Nick


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