[Geoserver-users] Image Pyramid Zoom Level control

Hi Geoserver Community,
I am building an OpenLayers application using GeoTiff map tiles.

My Question:
Is there any way to control the scale/zoom level "entry" and "exit"
points for each level of a pyramid?

Background:
I have a few gigs worth of map tiles at different map resolutions.
However the step between the resolutions is not 0 2 4 8 16 etc it is
more like 10 20 40 200 1000.
I am using the layers I already have in my pyramid rather than
creating overviews from the bottom layer.
I have created an imagemosaic for each level of the pyramid.
I then created an imagepyramid and imported it into GeoServer using
the ImagePyramidal plugin.

I am using OpenLayers to view my result.
I get seamless zooming between the different layers and all the levels show up.

The problem I am facing is that it enters and exits the levels too
early and hence its a little slow and shows too much complexity on the
map at certain zoom levels. Is there a way to control which level of
the pyramid is shown at a particular scale or zoom level?

I could create intermediate levels within my pyramid using gdal_warp
by simply halving the size of the original map tiles but this seems
like a cumbersome and unnecessary workaround as I already have enough
levels to do what i want to do - i just need to control what is
displayed when.

Sorry if my terminology is incorrect - i am from a telecoms background
and a GIS novice.

Thanks

James

Ciao James,
please read below...

On Thu, Oct 16, 2008 at 2:21 PM, James Cauchi <jamescauchi@anonymised.com> wrote:

Hi Geoserver Community,
I am building an OpenLayers application using GeoTiff map tiles.

My Question:
Is there any way to control the scale/zoom level "entry" and "exit"
points for each level of a pyramid?

Background:
I have a few gigs worth of map tiles at different map resolutions.
However the step between the resolutions is not 0 2 4 8 16 etc it is
more like 10 20 40 200 1000.
I am using the layers I already have in my pyramid rather than
creating overviews from the bottom layer.
I have created an imagemosaic for each level of the pyramid.
I then created an imagepyramid and imported it into GeoServer using
the ImagePyramidal plugin.

I am using OpenLayers to view my result.
I get seamless zooming between the different layers and all the levels show up.

Great :-). I might ask you to describe the procedure in our wiki!

The problem I am facing is that it enters and exits the levels too
early and hence its a little slow and shows too much complexity on the
map at certain zoom levels. Is there a way to control which level of
the pyramid is shown at a particular scale or zoom level?

The short answer is not, Of course there is a longer answer which i am
going to give you now.
The various coverage plugins can be instructed to use various
different policies for picking up the correct overviews, default,
quality, speed, etc.. The problem is that this is not exposed in the
GeoServer UI at the moment, hence GeoServer always uses the default
behavior (nearest overview). I would suggest you open up a JIRA bug
for this in the GeoServer project so that we can take care of it.

Simone.

I could create intermediate levels within my pyramid using gdal_warp
by simply halving the size of the original map tiles but this seems
like a cumbersome and unnecessary workaround as I already have enough
levels to do what i want to do - i just need to control what is
displayed when.

Sorry if my terminology is incorrect - i am from a telecoms background
and a GIS novice.

Thanks

James

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