4D Raster access NOT via WMS?
Samuel Hiatt
samhiatt at GMAIL.COM
Wed Oct 24 19:28:52 EDT 2007
Thanks for your help! I can always count on the pros at DM. :)
I'm still a bit unclear about how the 3-D rasters (lat,lon,time) should be
set up in the mapfile. Is there a way to define a 3-D layer in the
mapfile? Or should I do something similar to what I would to set up the n-D
WMS (with a tile-index)?
Thanks!
Sam
On 10/24/07, Yewondwossen Assefa <assefa at dmsolutions.ca> wrote:
>
> Samuel Hiatt wrote:
> > Can anyone help with this last question? I'm hesitant to start hacking
> > at this 'cause I don't really feel like re-inventing the wheel...
> > again. Is anyone familiar with the mechanism that is used when
> > mapserver gets a WMS request with a TIME parameter? Maybe the solution
> > lies there.
> >
>
> > The metadata tags required to make 4D WMS layers work all have "wms_
> > ..." at the beginning. I imagine that extending this functionality to
> > any type of mapserver request (WMS, mapscript, CGI) would be very
> > valuable (if it doesn't exist already).
> >
>
> As explained earlier, the wms will take the time parameter and
> transform it to a valid time expression and set the FILTER element of
> the layer with that expression.
>
> wms_xxx tags are there to hold information so that this tarnsformation
> can be done (hold information such as which is the time field on the
> layer, extents of valid time, default valid time ...). Most of these
> things are specific to the wms specification
>
> In you case, if you are using scripting, you should do the same
> operation of transforming the time parameter to a valid time filter and
> set it on the layer (time parameter like 2004-10-12 could be transformed
> to (`[time_field]` eq `2004-10-12). Although the underlying code exists
> in MapsServer to parse different kind of time values, there are no
> currently mapscript functions that would do that for you so you need to
> write your functions.
> You map file does not need to have any wms_xxx parameters. It is a
> regular map file and the time is just another type of expression that
> can be used on the FILTER element of the layer (or on the class object)
>
> Hope this helps.
>
> Best Regards,
>
> > Thanks for your help.
> >
> > Sam
> >
> >
> >
> >
> > On 10/12/07, *Samuel Hiatt* <samhiatt at gmail.com
> > <mailto:samhiatt at gmail.com>> wrote:
> >
> > Thanks for the help.
> >
> > It should be very easy to filter my files for time. What should my
> > mapfile look like for the 4D layer? The same thing as for a 4D wms
> > layer, with the tile index and wms_* metadata tags but I would use
> > mapscript to screen the files? Do you know of a way I might reuse
> > the screening code that is used for 4D WMS?
> >
> > Thanks!
> > Sam
> >
> >
> >
> >
> > On 10/12/07, *Yewondwossen Assefa* < assefa at dmsolutions.ca
> > <mailto:assefa at dmsolutions.ca>> wrote:
> >
> > Samuel Hiatt wrote:
> > > Hi! Thanks for the reply.
> > >
> > > So I suppose when I make a WMS request with TIME Mapserver
> > applies the
> > > filter behind the scenes, finding which feature in my
> > tile_index.shp
> > > represents the correct time and then processes the raster
> > pointed to by
> > > that feature? So if I want to implement the same kind of
> > thing with
> > > mapscript I'd have to write the filter myself?
> > >
> > That is correct : assuming that the underlying data can be
> > filtered
> > using a time field, you need to know the attribute and build the
> > time
> > expression and set it using mapscript.
> >
> > > The reason I am interested in doing this is to extend
> temporal
> > > functionality to ka-map. I may end up abandoning that
> > approach and
> > > moving to a javascript WMS client (like OpenLayers of
> > MapBuilder) instead.
> > >
> > > Thanks for your help.
> > >
> > > Sam
> > >
> > >
> > >
> > > On 10/11/07, *Yewondwossen Assefa* <assefa at dmsolutions.ca
> > <mailto:assefa at dmsolutions.ca>
> > > <mailto: assefa at dmsolutions.ca
> > <mailto:assefa at dmsolutions.ca>>> wrote:
> > >
> > > Hi there,
> > >
> > > The Time parameter that is sent with a WMS request is
> simply
> > > converted
> > > to a time expression and set on the filter object of the
> > layer. In the
> > > case of wms. the metadata wms_timeitem will be used for
> the
> > > attribute name.
> > > if you are using mapscript, you would need to build the
> time
> > > expression manually and set the filter parameter. Please
> > refer to
> > > http://mapserver.gis.umn.edu/docs/howto/wms_time_support
> > (section 2.5)
> > > to see how time parameters are interpreted.
> > >
> > > Best Regards,
> > >
> > >
> > > Samuel Hiatt wrote:
> > > > I am excited to see that Mapserver supports 4D raster
> > layers for WMS,
> > > > but I am curious if this functionality can be extended
> > to mapscript
> > > > calls as well? For example, if I set up a raster layer
> > with a TIME
> > > > dimension then will it be possible for me to request an
> > image for a
> > > > specific time with mapscript? Or would I have to do
> > this with a
> > > WMS call?
> > > >
> > > > Thanks!
> > > >
> > > > Sam
> > >
> > >
> > > --
> > >
> > ----------------------------------------------------------------
> > > Assefa Yewondwossen
> > > Software Analyst
> > >
> > > Email: assefa at dmsolutions.ca <mailto:assefa at dmsolutions.ca
> >
> > <mailto: assefa at dmsolutions.ca <mailto:assefa at dmsolutions.ca>>
> > > http://www.dmsolutions.ca/
> > >
> > > Phone: (613) 565-5056 (ext 14)
> > > Fax: (613) 565-0925
> > >
> > ----------------------------------------------------------------
> > >
> > >
> >
> >
> > --
> > ----------------------------------------------------------------
> > Assefa Yewondwossen
> > Software Analyst
> >
> > Email: assefa at dmsolutions.ca <mailto:assefa at dmsolutions.ca>
> > http://www.dmsolutions.ca/
> >
> > Phone: (613) 565-5056 (ext 14)
> > Fax: (613) 565-0925
> > ----------------------------------------------------------------
> >
> >
> >
>
>
> --
> ----------------------------------------------------------------
> Assefa Yewondwossen
> Software Analyst
>
> Email: assefa at dmsolutions.ca
> http://www.dmsolutions.ca/
>
> Phone: (613) 565-5056 (ext 14)
> Fax: (613) 565-0925
> ----------------------------------------------------------------
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/mapserver-users/attachments/20071024/02665ffc/attachment.html
More information about the mapserver-users
mailing list