[mapserver-dev] MS RFC 68: Support for combining features from multiple layers (Call for discussion)

Tamas Szekeres szekerest at gmail.com
Mon Feb 14 10:03:57 EST 2011


Hi Jeff,

'Cluster:FeatureCount' would be added to the CLUSTER layer as an additional
attribute. In this regard it can be used as the text data when labelling the
features, I imagine something like:

LAYER
  TYPE POINT
  NAME cluster
  CONNECTIONTYPE CLUSTER
  PROCESSING "SOURCELAYER=layername"
  CLASS
    EXPRESSION ([Cluster:FeatureCount] > 1)
    TEXT ([Cluster:FeatureCount])
    LABEL
    ...
    END
  END
  ...
END

I would prefer this option to work even with the STYLEITEM "AUTO" setting,
where the styles for the source layer would be retrieved only for the
individual shapes not for the clustered shapes. I hope I can provide a
working example soon.

Best regards,

Tamas



2011/2/14 Jeff McKenna <jmckenna at gatewaygeomatics.com>

> Hello Tamas,
>
> This is a very interesting proposal.  I often have a hard time to picture
> these changes beforehand, but I am trying to now and I have a question: when
> it comes to clustering, I think a common need is also to label the number of
> clustered points...and since you'll know how many features are combined
> according to your proposal (I see 'Cluster:FeatureCount' mentioned in the
> RFC) I believe we must also expose this clustercount in the label object.
>  How I am not sure, but to me this will be a common need.  Or is this
> mentioned in the RFC already?
>
> -jeff
>
>
>
>
> On 11-02-10 6:02 PM, Tamas Szekeres wrote:
>
>> Hi Devs,
>>
>> In reference to the feature request from WhereGroup
>> <http://www.wheregroup.com/en/welcome> we did some refinement in the
>>
>> specification and I've created MS-RFC-68
>> (
>> http://trac.osgeo.org/mapserver/browser/trunk/docs/en/development/rfc/ms-rfc-68.txt
>> )
>> which contains a reasonable implementation to this option without
>> requiring significant modifications in the MapServer codebase and the
>> current processing chain. With regards to the timing, I already have
>> some working code in place which could be finished by the time of the
>> feature freeze of MapServer 6.0 we are targeting now (feb. 28).
>>
>>
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