Drawing Raster Query Results

[Tamas Szekeres]

Steve,

I haven't been thinking of spanning new layers on the fly or even
dropping out this approach storing the FID-s instead of the whole
shape. Instead I would like to see a certain number of layers holding
the results. For example one additional layer implicitly assigned to
each layer with a special provider providing the results of the query.

The user should use the result set for subsequent queries (expanding
and narrowing the set in effect) or she may choose to delete the
results explicitly. According to the ESRI ArcGIS solution:

http://webhelp.esri.com/arcgisdesktop/9.2/index.cfm?TopicName=Using_selection_layers


Best regards,

Tamas


2007/4/24, Steve Lime <Steve.Lime at dnr.state.mn.us>:
> Result sets can span many layers and data types so it can get messy very quickly.
>
> Steve
>
> >>> On 4/23/2007 at 4:48 PM, in message
> <f3b73b7d0704231448j82fd0fwd93ad441737ec146 at mail.gmail.com>, Tamas Szekeres
> <szekerest at GMAIL.COM> wrote:
> > 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
> >>
>
>