[thredds] aggregating gridded (tiled) netcdf files along lat and long to form one WMS layer


Hi there,

apologies for this, i am sure its a stupid question but i have spent too much time already. I have a large number of netcdf files that are actually arranged as a grid/tiled fashion, (file-001-001, file-001-002..) .. representing the same variables and dimensions and points in time, just different spatially.

i want to make a virtual dataset that is the combination of all the tiles..which i will then map via WMS.

i have tried aggregating on the lat/long dimensions like this:

<netcdf xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";>
<aggregation dimName="latitude" type="joinExisting" recheckEvery="4 sec">
<netcdf xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";>
<aggregation dimName="longitude" type="joinExisting" recheckEvery="4 sec">
<scan location="E:/save/agg/" regExp="files_26_04_2011.nc.*" />
</aggregation>
</netcdf>
</aggregation>
</netcdf>


but it is not working, i get a 'smeared' version of a single tile.. and tried doing a simple union like this:

<netcdf xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";>
<aggregation type="union">
<scan location="E:/save/agg/" regExp="files_26_04_2011.nc.*" />
</aggregation>
</netcdf>

but i get only one tile rendered via WMS.

I cannot find any references to aggregations based on any dimension other than time, and am wondering if this is even possible.. but it seems like such a common thing to do i must be doing something dumb. i found one reference to a type of aggregation called 'tiled' but no doco anywhere for it.. maybe this is what i need ?

any suggestions would be appreciated

cheers

-i