Using WMS time dimension with rasters?

[Paul Ramsey]

Jeff,

Support for the time dimension in rasters exists, you just have to  
take a slight detour to get there.  You want to use a "tile index" in  
your raster layer.  This is a vector file that contains one record  
for each raster file.  The shape should be the outline of the  
raster.  It should have at least one attribute, which contains the  
file path to the raster file.  For time based data, it will contain a  
second attribute, the date associated with the raster file.

The vector "file" can be any of the Mapserver vector formats, so it  
can be shape file, or a postgis table, or an oracle table, etc.  You  
can use the "tile4ms" (either part of mapserver or gdal, I am not  
sure) command to create a tile index from a directory of data, though  
it won't fill out a time stamp attribute for you.

So, when mapserver is told to draw an image, it will (a) first look  
in the tile index to see what images fit the spatial and time extents  
being requested then (b) open up those images and draw them into the  
output image then (c) return the result.

Yours,
Paul

Refractions Research
www.refractions.net



On 10-Oct-05, at 11:22 AM, Jeff Schmaltz wrote:

> Hello,
>
> I am exploring the possibility of using MapServer to serve up MODIS
> satellite imagery as a WMS.
>
> I have managed to create a working mapfile containing a single  
> raster image
> for a single day.  I need to to serve up a 2nd image which covers  
> the same
> geographic extents but is from a different date.  Ultimately, I  
> want to
> serve up years of daily images, hence my desire to use the time  
> dimension.
>
> Searching the MapServer documentation - in the "WMS Time Support  
> HOWTO", I
> found the statement "wms_ timeitem: (Mandatory) this is the name of  
> the
> field in the DB that contains the time values".  I am surmising  
> that "DB"
> refers to database and that PostGIS is the open source database one  
> would
> use with MapServer.  From the PostGIS Manual FAQ "You can store  
> point, line,
> polygon, multipoint, multiline, multipolygon, and  
> geometrycollections."
>
> Therefore, I have come to the conclusion that it is NOT currently  
> possible
> to use the WMS time dimension for raster data.
>
> 1) If I am wrong, can someone please point in the right direction  
> to use the
> time dimension in a WMS for rasters?
>
> 2) If I am right, can someone please tell me if support for time  
> dimension
> for WMS rasters is coming anytime soon in MapServer?
>
> Thank you,
>
> Jeff
>
> Jeffrey E. Schmaltz  (SSAI)
> MODIS Rapid Response Team
> NASA Goddard Space Flight Center
> Building 33 Room G108  Code 614.5
> Greenbelt, MD 20771 - USA
> Voice: (+1) 301 614 5135
> Fax:   (+1) 301 614 6015
> E-mail: Jeff.Schmaltz at gsfc.nasa.gov
> URL: http://rapidfire.sci.gsfc.nasa.gov
>