mapserver WMS time and postgis.

[Denis Nadeau]

Hi,

I would like to change some of the  code in mappostgis.c to reflect C
5.2Nearest Value instructions found in  WMS
1.1.1 specifications for "TIME" parameter.
http://portal.opengeospatial.org/files/?artifact_id=1081&version=1&format=pdf

Here what it says in the WMS 1.1.1 doc.

"If a request does includes an imprecise dimensional value, and nearest
value behavior has been declared, then the server shall compute and send the
nearest available value. The value shall be rounded, not merely truncated."

Right now, mapserver is using date_trunc function to allow the user to
specify months, days, hours or minutes.  I think this could be enhanced to
get the nearest time value in Postgres.  For example,  NASA GES has 3 hourly
data.  If the user  specify 2006-09-28T02:00  a blank image is return, the
user needs to be exact 2006-09-28T03:00.  Same thing with 10-day data,
2006-09-03 will  return a  blank image.  User have to hit the right date
2006-08-10, 2006-08-20, 2006-08-31, 2006-09-10,....

Example
Tropical Rain data 3B42_V6_10_DAY:
http://g0hep12u.ecs.nasa.gov/mapserv-bin/wms_ogc?SERVICE=WMS&VERSION=1.1.1&REQUEST=Getmap&layers=bluemarble,TRMM_3B42_V6_10_DAY&BBOX=-180,-50,180,50&TIME=2005-08-20

blank image
http://g0hep12u.ecs.nasa.gov/mapserv-bin/wms_ogc?SERVICE=WMS&VERSION=1.1.1&REQUEST=Getmap&layers=bluemarble,TRMM_3B42_V6_10_DAY&BBOX=-180,-50,180,50&TIME=2005-08-20T04:00


Let me know if this make sense to you.  I would be happy to contribute some
coding for this.


Denis
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