[Geoserver-users] Ordering/Rendering in Group Vector Tiles / OpenLayers

GeoServer GeoServer User
1

Hi All,

Im looking to know if it is possible to control the rendering/z order in the following:

Geoserver:

  • Group Layer (mapbox vector tile, pbf)

  • Layer A

  • Layer B

Given both Layer A and Layer B have a common field called “access_code”… and values that I would like rendered (top first)…

  1. access_code = Restricted
  2. access_code = Approved with Conditions
  3. access_code = Approved

And, the client is OpenLayers.

We would like access_code = Restricted always on top (regardless of being in A or B) and so forth…

Is there an SLD/CSS option that will control the sorting/ordering of the data so that it streams out the pbf and rendered in such an order? or perhaps we need to split Layer A and B into a total of 6 layers within the group layer…

Layer A - Restricted

Layer B - Restricted

Layer A - Approved with Conditions

Layer B - Approved with Conditions

Layer A - Approved

Layer B - Approved

Or… something else? or nothing else will work?

Any help would be greatly appreciated.

Cheers,
Andrew

2

Hi Andrew,

FeatureTypeStyle is each drawn into its own buffer which is then merged during composing the final image.

  • FeaureTypeStyles are used in the order defined

  • If this default order is not desired there are some vendor options for greater control of z-order

  • You can adjust the alpha and blending effects when buffers are merged as a special effect

  • You can also control z-order by introducing filtering (to control what order features are drawn in within a z-order).

Best documented in the GeoServer manual on “sld extensions”.

And with pictures here:

···

–
Jody Garnett

3

Hi Jody,

Thanks so much for the response.

I may have not been clear enough in my question - my bad. But this is for vector tile (pbf). All doco appears to only discuss sever side rendering which is not applicable for us.

We did have some success with “ORDER BY” in our sql/views (however this is less than ideal performance wise).

If you have any more advice, I would really appreciate it

Many Thanks,
Andrew

···

–
Jody Garnett

4

Hi Andrew,
as far as I can see, the code setting up queries to fetch data for vector tiles are simply not aware of the sortby vendor parameters
in your style, and thus, are not accounting for them. It’s not a big change, but nevertheless, one that requires some code development,
test writing and the like.

See this guide on how to make the necessary development happen:
https://github.com/geoserver/geoserver/wiki/Successfully-requesting-and-integrating-fixes,-improvements-and-new-features-in-GeoServer

···

Regards,

Andrea Aime

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