[OpenLayers-Users] tiling based upon dynamic map parameters

[scottpez]

Hello,

I have a task I am trying to wrap my head around. Below is what I want to
do. I am hoping someone can point me in the right direction. I am using
OpenLayers as my mapping client and Mapserver.

I'd like to have an image layer that is dynamically drawn from request
parameters. I have been able to do this with a singleTile=true layer, but
then every time I move the map, change the browser window size, etc. the map
draws again. I am pulling data from Postgresql/PostGIS and because of the
large amount of data I have, these requests are extremely slow.

I thought my solution could be drawing the image as singleTile=false. This
seems to work better because the image tiles are drawn less often but now I
have an unexpected tricky issue. My dynamic requests for maps produces a
grid symbolized as quantiles by data counts by Mapserver. When I set
singleTile=false, the requests are broken down into the tile requests and
then each tile has its own quantiling result.

It seems what I need is a way for OpenLayers to make a single tile request,
have Mapserver make the single tile request from PostGIS, have either
Mapserver or a tiling software break the single tile into multiple tiles and
have OpenLayers handle the multiple tiles returned. But then maybe there is
something I am missing.

I hope my explanation makes sense and please let me know if this could be
posted in a different forum. Thank you very much in advance for any advice.

Scott


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