If the goals are:
- maintain only one copy of the styling for a given feature type
- display different versions of a feature depending on scale
then perhaps you could merge all feature versions of the same feature type
into a single table, with an attribute indicating the appropriate scale,
and then render that layer with a single SLD.
Since the scale is indicated by an attribute, the standard SLD
Min/MaxScaleDenominator elements can't be used, because they are static.
Instead, use a rule filter based on the current scale, as provided by the
"wms_scale_denominator" environment variable [1]. <PropertyIsBetween> is
one way to express this, or else use the "between" function.
This also allows having just a single copy of the styling for a feature,
applied at all desired scales (the rule filter can AND the valid scale
range conditions for a particular styling together).
[1]
http://docs.geoserver.org/stable/en/user/styling/sld-extensions/substitution.html#predefined-variables
On Fri, Sep 14, 2012 at 3:01 AM, Christian Weithoeft
<christ...@dashsoft.dk>wrote:
>
> Hi Christian
>
> >From another Christian on the other side of the world.
>
> Could you please elaborate a little on this. Being new to GeoServer I'm
> struggling to understand and use all the different aspects of layers, layer
> groups and styles.
>
> My task is to display different layers dependent on scale. Example could be
> cost-lines with different level of details used for different scales. Layer
> for 1:1.000.000 has fewer details than the corresponding layer for 1:50.000
> and so on.
>
> On the other hand I want to use the same style for the feature independent
> of scale. And I don't want to have to maintain the same style in a lot of
> different SLD's. (it always goes wrong at some point in maintenance,
> forgetting one in the update process)
>
> How can Layer group help me or rather can I use layer group to select the
> "correct" layer for display dependent on scale.
>
> The data are placed in a Oracle Spatial database. The data is presently in
> use in an MapInfo based web tool. And from design data has been split into
> separate tables for each feature/scale combination.
>
> I have the option of joining the data in one table and add a label to
> indicate which scale data is meant to describe. The data are not very
> dynamic, so data maintenance is a smaller issue.
>
> --
Martin Davis
OpenGeo - http://opengeo.org
Expert service straight from the developers.
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