[OpenLayers-Dev] singleTile optimization

David William Bitner david.bitner at gmail.com
Thu Oct 4 09:36:16 EDT 2007


Great to see you here -- don't be a stranger.

The problem with aligning singleTile to a grid is that as soon as you have
the corner of the grid on the screen, all the sudden you are in a tiled mode
only with larger tiles.  It strikes me that for any use case that would
require any kind of grid alignment at all, really you should be using a
tiled mode only with perhaps larger tiles and smaller buffers.  The use case
that I see for single tile is for dynamic data -- data that is dynamic
enough that you wouldn't want it cached at all, ever.


On 10/4/07, Dan Little <danlittle at yahoo.com> wrote:
> Yikes, first time poster!
> I think the speed to generate a single tile is wholely dependent on the
> map-rendering engine and the dataset.
> For example, here at the City of Saint Paul, our streets layer is entirely
> vector.  I can generate a very very large tile with highly detailed streets
> for the entire city using Mapserver in less than 1/3 of a second.  Given the
> nature of MapServer, and the size of the shapefile which stores our streets
> layer, multiple tiles is much much slower (as the shapefile needs to be read
> from disk and loaded to memory for each rendered tile).  It would be nice to
> have some of the effects of tiling without the high-cost it currently
> presents in rendering performance.
> Dan "Ducky" Little
> City of Saint Paul / Public Works / GIS
> ----- Original Message ----
> From: Stephen Woodbridge <woodbri at swoodbridge.com>
> To: pspencer at dmsolutions.ca
> Cc: dev at openlayers.org
> Sent: Wednesday, October 3, 2007 9:37:29 PM
> Subject: Re: [OpenLayers-Dev] singleTile optimization
> pspencer at dmsolutions.ca wrote:
> > What do you think about aligning singleTile bounds to the grid to
> > promote cacheability in the client?
> I think that this should be an option in the layer definition if it gets
> done. I can see some benefits to doing this, but the down side is that
> all images generated will be larger and slower to generate and the
> singleTile option needs to support more than one use case in my mind
> anyway.
> -Steve
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David William Bitner
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