[OpenLayers-Users] Tilecache Overlay Not Displaying Properly

[Blake Crosby]

What I ended up doing was using the transform() function to convert my 
data in the database from ESPG:4329 to EPSG:900913.

Blake

Blake Crosby wrote:
> Hello,
> 
> I've been pulling my hair trying to figure out how to get this working 
> properly.
> 
> Here is my current set up.
> 
> Openlayers front end
> Tilecache to generate tiles
> Mapnik to generate maps
> Posgres to store data.
> 
> I would like to overlay my data on top of a google map (Mercator). 
> However my data is stored in lat/long WSG84 projection.
> 
> I've tried every combination of configuration options. The closest I've 
> gotten to is displaying my overlay at 0,0 on the map. The data is so 
> small, that you would have to zoom in beyond level 15 to see it properly.
> 
> It just appears as a little purple speck.
> 
> You can see an example here:
> 
> http://gateway.infiniteloop.ca/~bcrosby/tilecache/index3.html
> 
> Here are various config options:
> 
> Tilecache:
> [airways]
> type=Mapnik
> mapfile=/home/bcrosby/flightplan/airway_layer.xml
> metaTile=true
> spherical_mercator=true
> 
> Mapnik:
> <Map srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 
> +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +no_defs">
> 
> (let me know if you need more information in the mapnik config) The 
> airways layer does not have an srs defined.
> 
> The data should be appearing over Canada, at a proper zoom level. I 
> suspect that there is a re-projection problem somewhere. Specifically, 
> the data in the database is stored in lat/long units, however the map 
> units are in meters. So tilecache/mapnik/openlayers is making requests 
> for the data in the database based on meters, and not lat/long.
> 
> Any suggestions?
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