[Mapserver-dev] Re: time support

[Brent Fraser]

Dave,

    Conceptually, the layer describing the individual tiles would be more
for specifying the rendering of the elements (colors, fonts, etc for
vectors, not very useful for raster), while the layer describing the tile
index would be for filtering/querying (both spatial and attribute, e.g.
time).  But you could use the full power of all the layer options if you
liked (more filtering on the individual elements, etc).

    As you point out, a query (spatial at least) would have to be performed
on the tile index layer, then for each record returned from the index, the
location of the tile would be used in processing the tile layer (this is
done in the current version anyways).

  Steve Lime had mentioned in a previous post that it would be no small
effort to add this layer-pointing-to-a-layer feature, and he is right.  We
would have to look at the effect this would have on the various objects and
attributes of a layer.  For example, what if the projection object of the
tile index layer was specified differently from the tile layer? (BTW Steve,
I've got code (not checked-in!) for that).

    There are benefits though....

Brent


----- Original Message -----
From: "David W. Graham" <dgraham at i3.com>
To: <mapserver-dev at lists.gis.umn.edu>
Sent: Thursday, January 15, 2004 10:40 AM
Subject: RE: [Mapserver-dev] Re: time support


> Brent,
>
> Your solution actually makes a lot of sense.  Often times I have the
> "TILEINDEX" shapefile in the MAP object as a layer unto itself called the
> "coverage" of the raster data.  This allows user to turn on a layer and
see
> the tile lines and names of the tiles (used in data management and
ordering
> apps).  But the problem still remains that nature of the query on the
> TILELAYER in order to find the locations for the actual image tiles.
>
> Any suggestions?
>
> Dave
>
>
> ________________________________________________
> David W. Graham
>
> Director of Application Development
> dgraham at i3.com
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> -----Original Message-----
> From: mapserver-dev-admin at lists.gis.umn.edu
> [mailto:mapserver-dev-admin at lists.gis.umn.edu] On Behalf Of Brent Fraser
> Sent: Wednesday, January 14, 2004 11:44 AM
> To: Steve Lime
> Cc: mapserver-dev at lists.gis.umn.edu
> Subject: Re: [Mapserver-dev] Re: time support
>
> Steve,
>
>   Here's an idea from left field.  The basic problem is we're on the road
to
> creating a layer-within-a-layer, adding new keywords and possibly changing
> the syntax of existing keywords.
>
> How about pointing to another layer (a tileindex layer) from the layer of
> interest?
>
> LAYER
>   NAME 'landsat images'
>   TYPE raster
>   STATUS on
>   TILEITEM "Location"
>   TILELAYER "landsat_tiles"  # new keyword; points to tile layer END
>
> LAYER
>   NAME 'landsat tile outlines'
>   TYPE polygon                     # or have a new type of  "tile" ?
>   STATUS off
>   DATA "index/landsat.shp"
> END
>
> That way we could leverage existing filtering, connection, etc structure
for
> the tile layer.  Might be too weird though....
>
> Brent
>
>
> ----- Original Message -----
> From: "Steve Lime" <steve.lime at dnr.state.mn.us>
> To: <morissette at dmsolutions.ca>
> Cc: <mapserver-dev at lists.gis.umn.edu>
> Sent: Wednesday, January 14, 2004 10:16 AM
> Subject: Re: [Mapserver-dev] Re: time support
>
>
> > I could create a single new keyword (e.g. TILES) and use the older
> > keywords to populate members of the new object. That's how styles work
> > so that older map files don't break. In effect:
> >
> > TILEINDEX 'foo'
> >
> > would be the same as
> >
> > TILES
> >   DATA 'foo'
> > END
> >
> > To take advantage of filtering you'd have to move to the TILES object.
> > The only
> > side effect would be that mapscript would break since
> > $layer->{tileindex} isn't real anymore. That was the same case with
> > styles.
> >
> > This seems a reasonable compromise to me anyway.
> >
> > Steve
> >
> > >>> Daniel Morissette <morissette at dmsolutions.ca> 1/14/2004 7:55:30 AM
> > >>>
> > Steve Lime wrote:
> > > Any comments out there? I kinda need to move swiftly...
> > >
> > >
> >
> > I am concerned by the fact that the new tileindex object would break
> > existing mapfiles.  Could we stick to shapefile tileindexes for this
> > release for now, since we don't have much time anyway, and perhaps in
> > a
> >
> > later release we could move a tileindex object and support tile
> > indexes
> >
> > in any format?
> >
> > I suppose the main drawback of this approach would be that we would
> > have to create TILEFILTER/TILEFILTERITEM which would have to be
> > deprecated later when we create the tileindex object.
> >
> > I dunno.... I think we should try to avoid breaking older mapfiles
> > unless we really have to... that's always a pain for users to upgrade
> > when we break the mapfile format.
> >
> > Daniel
> > --
> > ------------------------------------------------------------
> >   Daniel Morissette               morissette at dmsolutions.ca
> >   DM Solutions Group              http://www.dmsolutions.ca/
> > ------------------------------------------------------------
> >
> > _______________________________________________
> > Mapserver-dev mailing list
> > Mapserver-dev at lists.gis.umn.edu
> > http://lists.gis.umn.edu/mailman/listinfo/mapserver-dev
>
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