Drawing Raster Query Results

[Tamas Szekeres]

Frank,

I'm personally not too pleased with the current resultcache approach
as the primary solution of storing a results of a query. Why don't we
add the results to a predefinied inline layer? This approach would
provide all of the facilities for styling the results as we have
normally for a layer. The user could additionally swich on/off this
layer or eventally start a subsequent query based on this previous
query in another layer for example.
Threating the raster layers as point layers is a bit quicky for me.

Best regards,

Tamas


2007/4/23, Frank Warmerdam <warmerdam at pobox.com>:
> Folks,
>
> A couple years ago I implemented support for "query" against a raster layer.
> Such queries essentially return a list of point features, generally one for
> each pixel that satisfies the query criteria.
>
> Recently a user has run into problems when they try to draw a map of the
> query result.  This isn't something I've ever tried before, and to be honest,
> I'm a bit vague on how queries are normally used in MapServer.  I assumed they
> were mostly used for populating tabular results which does work fine.
>
> The drawing a query layer for a map result doesn't work properly, as documented
> in:
>
>    http://trac.osgeo.org/mapserver/ticket/2069
>
> The question, to my mind, is whether it makes sense to try and draw point
> features from a raster query result on a map, and if we did so how do we
> differentiate styling used for the raster from styling used for the query
> results which are a very different sort of data.
>
> I'm tempted to modify msDrawQueryLayer() to do nothing raster layers, but to
> issue a debug message indicating that the layer is being skipped since drawing
> raster query results is considered an unclear request.
>
> If anyone has an opinion contrary to my idea to disallow this, please let me
> know on this list, or via the ticket.
>
> Best regards,
> --
> ---------------------------------------+--------------------------------------
> I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush    | President OSGeo, http://osgeo.org
>